# Pouring exactly 1 troy ounce at a time



## Anonymous

I am a long time gold dealer. Lately I have been wanting more and more to refine my gold myself. I have mapped out the process in theory, but there is one aspect that I can not get a handle on.

How does one pour exactly 1 troy ounce of gold?

Since people prefer standard denominations, I want to be able to pour exactly 1 troy ounce. I can buy the ingot tray/mold for 1 ounce. But, how do I pour exactly 1 ounce in. Do I pour in more then one ounce, then let it harden, and slowly file away gold until it weighs exactly 1 ounce. It seems like this would take too much time to do it this way.


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## Harold_V

You don't. You also do NOT alter ingots. Once an ingot shows sign of having been altered, the markings have no credibility. How is one to know that the weight is as presented without re-weighing? 

Your options are to either shoot for an ounce and settle for the results, marking accordingly, or to roll gold to a specific thickness, punch planchets and form ingots in a die. Assuming the target weight of the desired ingot is missed, the planchets can be adjusted for weight because the forming will cold flow the material, filling the die completely, assuming you have enough tonnage for the press. 

As an individual, it isn't likely you can benefit from the second option. Not only does it require a large investment, there isn't the demand for gold from unrecognized sources, although it's possible you can produce an excellent product. 

One easy option is to serve the manufacturing industry, where refined gold of high quality (9995 or better) can be poured to shot and sold to jewelry manufacturers. That, too, may be difficult in that not all jewelers will trust an unknown source. The nice part is you can do this without expending funds for equipment that you may not use. 

Harold


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## qst42know

You could shot it first and only melt an ounce at a time adding a couple grains to be sure.


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## Harold_V

qst42know said:


> You could shot it first and only melt an ounce at a time adding a couple grains to be sure.


That is not a solution. Not all of the gold will pour each time, and there are times when it will. The difference is what creates the problem, being an unknown. By adding extra weight, occasionally the right amount will pour, but, in general, you'll find you get random ingots, in spite of your hardest and best attempts. I spent a great deal of time on this issue and never managed to master a process that was reliable. 

A good portion of the problem comes from a miniscule amount of gold that remains in the melting vessel, then gets combined with the following heat. It is not consistent, but random. Unless you weigh each ingot after it is poured, and calculate the amount left behind, you run blind. Even that may not be a solution, especially if the feed is gold powder, as opposed to gold that has been once melted. 

Unless you are willing to mark the as cast condition, you can find yourself melting the ingots time and again in the hopes of achieving your intended goal. 

Note the markings on the ingots pictured, below. The target weight in all cases was ten ounces. 

Harold


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## butcher

beutiful gold , that would pay off my property, then wouldnt be giving my money away in interest.


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## qst42know

I would assume rolling to an exact thickness would also lead to minute errors as well. It wouldn't require much thickness error to change the weight greatly. Even the film from the US mint shows them edge trimming the slugs before coining to achieve a precise weight. I would guess Harold's ingots to be as near to precise as would be practical for all but the fattest wallets.


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## viacin

Question. Why not just melt it into shot, then send it to some place like kitco and have them send you back minted bars? I don't mean for them to actually melt your gold, but just exchange your shot for bars like credit suisse or whatnot. I know you will be losing 2% + the fee's, but perhaps it would be worth it if you took the time it takes to make the ingots and process more gold instead - plus the gas, mold, and stamp savings. 

This could be a time saver, plus you no longer have the worry associated with stamping your bars .999%. Also, it eliminates the fact that people do not like buying gold from unrecognized sources, as Harold had mentioned.

Any thoughts?


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## Harold_V

Your suggestion is likely spot on, assuming you don't mind taking a huge loss on the transaction. If you think these entities are there for your pleasure, you have a great deal to learn yet. 

Their purpose is to make money----which they do by charging fees for everything they do----as well as by paying less than value for material submitted, and selling for greater value. Anything that is submitted will be considered as impure, so there will be fees attached for sampling, plus fees for the exchange. You might find you'd be just as well off to submit the scrap as to go through the process of recovery and refining. All depends on the nature of the scrap, of course. E scrap may well be an exception, but you'll earn every dime that comes from processing the stuff. 

There's considerable satisfaction in properly refining your values and casting your own ingots. In time, you will even become recognized for your skills, assuming you achieve a high level of purity. I'd encourage anyone that is interested in doing so to pursue casting and properly marking their gold. 

Harold


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## SilverFox

Harold_V said:


> Your suggestion is likely spot on, assuming you don't mind taking a huge loss on the transaction. If you think these entities are there for your pleasure, you have a great deal to learn yet.
> 
> Their purpose is to make money----which they do by charging fees for everything they do----as well as by paying less than value for material submitted, and selling for greater value. Anything that is submitted will be considered as impure, so there will be fees attached for sampling, plus fees for the exchange. You might find you'd be just as well off to submit the scrap as to go through the process of recovery and refining. All depends on the nature of the scrap, of course. E scrap may well be an exception, but you'll earn every dime that comes from processing the stuff.



Great Answer!



> There's considerable satisfaction in properly refining your values and casting your own ingots. In time, you will even become recognized for your skills, assuming you achieve a high level of purity. I'd encourage anyone that is interested in doing so to pursue casting and properly marking their gold.
> 
> Harold



Honestly if I had not lost my dive shop to creditors I would pay for your advice, it has been instrumental in my steering my development.


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## viacin

Well Harold, you're right. If you are in this for the fun and personal enjoyment that refining brings, then there is no substitute for good 'ole homemade ingots. And if you have already processed it, then it may be cheaper to complete the steps and make your own bars. However, your answer has raised a question in my mind....if you consider only the monetary gains. 

Why refine at all? Why not simply buy scrap from Point A and sell it to us refiners at Point B for your profit? Hardly any overhead, no chemicals to worry about, no actual work involved, and you make your profits very quickly with almost no trouble at all. We all know how high just a bit of scrap jewelry sells on ebay, usually well over the price of the gold in it. Why not join their ranks? Do I speak of treason? I hope not. I must admit, once you get the gold fever it's hard to fight. Seeing your gold in a beaker is just as good, if not better, as seeing it in a gold pan as far as I'm concerned. 

However, I'm still looking for that "Point A". I'm sure it exists, but so far every source for scrap jewelry I have followed has turned out a dead end. Estate sales, auctions, advertisments, etc. It seems everyone is in on the great gold grab and is willing to pay too much for it too. I would like to hear some of the pro's "Point A's" to be honest. But that's like asking a shark to share his catch. Hardly going to happen I would think.


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## Lou

A lot of it is just how you talk to people and how you come across to them. Be professional and persuade them that going through you is the best option for them. There will be people that will stonewall you no matter how adroit you are, but those are often the guys you want to earn as clients.

If you're looking for Point A, best look into scrap that not many people know how to process or go after. Look on ebay at dental scrap--I've spent about $10K on dental gold (both used an as pennyweight ingots) from ebay and I've probably made about 25% on it, and that's just sending it straight to ARA (and another) and letting them handle it. That's after insurance, shipping, and market fluctuation. Much of this came off of one fellow who did consignment for the dental industry--he bought a bunch of material from a dental lab, and I bought a bit off of him, he liked dealing with me, so we started dealing outside of ebay, saving him fees, and me competition.


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## Harold_V

viacin said:


> Why refine at all? Why not simply buy scrap from Point A and sell it to us refiners at Point B for your profit?


It all depends on one's objective, eh?

It may come as a surprise to readers, but I refined gold for more than nine years before I sold as much as a grain. My interest was not in making money, but in owning gold. I already had a good income and had enough money to cover my needs, which are small. I do not buy a new car because the neighbor does. I dictate the terms of my life, I do not allow his choices to influence mine. 

When I started refining, it was illegal to do so without a federal license. Screw them, I said to myself. That sounds like way, way, way too much government control. I'll just figure this thing out on my own and refine, storing gold for my retirement. 

By the time I started selling gold, I was well recognized as a gold refiner and had a strong following. All restrictions on processing and possessing gold were eliminated on Jan. 1, 1975, which allowed me to be vocal about my hobby-----a hobby that was virtually unheard of because of previous regulations. I was in the right place at the right time for a business to blossom, although that was never my intention. 

Selling for spot was no big deal, a simple phone call to given customers and it was gone. The customer got a good deal because they bought for spot----which they, otherwise, were unable to do. 

So then, the objective of each individual is what matters. 

I have little patience with the guy that thinks he will stride into a situation, grab all the values and dump them in the lap of a refiner, making a killing in the process. These morons usually do little more than muddy the water for those that have good intentions. If any of the readers of this forum think they're going to skin a fat lamb by dealing in precious metals, they're in for the surprise of their lives. The precious metal market is exceedingly fickle. I sat watching the gold market for more than 20 years, with many of them with gold in the $300 arena. In those twenty years, I saw it run up to $500 and fall back, often well below the price of production. 

You doubt my comment about a fickle market? How then would you account for the price of rhodium----which was over $10,000 not too long ago?

Bottom line? If you are interested in being a refiner, it is important to serve the needs of your primary customers. If they are people that deal with ingots, that's what you must provide. If you rely on a second or third party to provide them, your chance of survival is small---for you'll make little money, if any, and if you cheat the customer to insure profit you won't last long enough to make it worthwhile. One unhappy customer can do more damage to one's reputation than can be healed with hard effort and a prolonged period of time. 

The choice is yours. Become a refiner, or find a different way to find entertainment. Or------simply stay the course and refine for your own pleasure, with no idea in mind of making profit. That way anything that comes from your activity can be looked upon as having made a dime. 

An added thought; the idea of hitting garage sales, flea markets and all the other sources you can conjure is a waste of time. That's not to say you can't, and won't, find the odd bit of precious metal. You will, but you can't make it a living. 

I snickered time and again as I talked with one of my customers, a prospector that had undying devotion. I accumulated more gold in two weeks than he did in a year, simply be refining for others for a percentage. There's nothing like going out looking for gold to put in focus the reason why it sells for the price it enjoys. It's damned hard to come by, be it via e scrap, where you put in a huge amount of labor, or by prospecting, which may *never* pay dividends. You have to use wisdom to make this thing work----with the niche market Lou spoke of the biggest part of success. 

Harold


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## Anonymous

I am really new to this, and still learning the termanology. My idea is when you get ready to melt the gold, add a little extra to compinsate for the amount that is left in the crucible after you finish pouring so that you make sure that you have enough. Also, you could take your empty ingots, place them on a scale, and zero the scale with the ingots on it. Then pour the gold into the ingot until the scale reads 1oz. If you have 4 spaces on one ingot, then pour the gold in the first space until the scale reads 1oz, and then pour the gold into the second space until the scale reads 2oz(1oz in the first space and pouring the second ounce) and so on.
Hope this helps.


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## Harold_V

Leviticus7 said:


> I am really new to this, and still learning the termanology.


You have far more than terminology to learn. You have yet to discover that the suggestions you provided 


> My idea is when you get ready to melt the gold, add a little extra to compinsate for the amount that is left in the crucible after you finish pouring so that you make sure that you have enough. Also, you could take your empty ingots, place them on a scale, and zero the scale with the ingots on it. Then pour the gold into the ingot until the scale reads 1oz. If you have 4 spaces on one ingot, then pour the gold in the first space until the scale reads 1oz, and then pour the gold into the second space until the scale reads 2oz(1oz in the first space and pouring the second ounce) and so on.


are worthless. 

Yes, they make sense on paper, but in practice they do not, nor will they ever---not pouring by hand. If you are familiar with a grain of gold, and how small it is, and consider a grain equates to 1/480th of a troy ounce, and an ingot is weighed to 4 places, a tenth of a grain effects the weight of an ingot by .0010 ounce. You simply can not control the pour to that degree of precision, nor will gold cooperate with tipping miniscule amounts. 

I'm not trying to be rude----I'm just trying to have you understand that you are dealing with infinitely small units, all of which are very important in the way of credibility. Ingots must weigh what they are marked, and establishing a desired weight is likely to be beyond your ability. You pretty much have to settle for random ingots unless you pour them heavy, then adjust their weight before die striking. That would create a uniform surface. The alternative is to roll gold to a specific thickness, punch a planchet, which would be adjusted for weight, then die struck. You would fail miserably at pouring ingots of a specific weight, although you will hit the occasional one. It happened for me, but rarely. It was not predictable in spite of considerable effort. 

Harold


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## Anonymous

Harold
What about a two part mold like a sinker mold? But obviously shaped like a bar, Known volume, cut off sprew(not sure about the spelling).

Jim


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## Harold_V

james122964 said:


> What about a two part mold like a sinker mold? But obviously shaped like a bar, Known volume, cut off sprew(not sure about the spelling).


It won't work. As the gold solidifies, it must contract. It would pull the characteristic pipe in the form, leaving a cavity. When ingots are poured, heat is played on the surface to slow cooling, so the ingot cools from the bottom up, shrinking the top surface somewhat uniformly. That way an almost flat ingot can be achieved, with no pipe. 

In a closed mold, the amount of shrink would relate to the temperature of the pour, so you'd get variations according to the temperature of the molten metal and/or the temperature of the mold. Further, controlling the amount of movement of the sprue cutter, closer or farther from the surface of the mold, would be cause for serious variations as well. Even bullets, cast in much softer lead, so they shear easier, aren't consistent (I used to cast my own bullets. Haven't hand loaded for years, but I still have the equipment). You also must hold the molten material in the sprue for a short interval while the lead freezes. You'd have more than a small amount of trouble doing that with gold, which will gladly solder to other metals, even under poor conditions. 

You have to understand the complexity of trying to meter the metal for this to make sense. You're dealing with a substance, be it gold or silver, that isn't a constant, nor will it pour in small amounts. If you start a stream of molten gold that is able to pour over a lip, you'll get one hell of a lot more gold than you bargained for before you can cut off the stream. Remember-------what you're concerned with is no larger than the tip of a pin---it takes almost nothing to alter the weight. It is for that reason that you see my ingots marked randomly. I did the best I could, but could hit the desired weight only very infrequently.  

The closest I could imagine you could come to success would be if you had a means of bottom pouring, and had a vessel that was covered with a very specific amount of borax. so the gold wouldn't stick, and would pour rapidly, coming out in one straight pour. It would be very important that none of the borax be discharged with the molten metal, thus the need for a specific amount. By that method, it's possible that none would remain behind. (Maybe!)

When pouring from a melting dish, when you start with a specific amount of gold, as the stream comes to an end, it generally leaves behind a miniscule amount of gold. Doesn't look like much, and it isn't, but when you weigh the ingot, what you had hoped to be a full ounce is short by enough to affect the weight in the third column. A tenth of a grain is a significant amount of gold when you're weighing an ingot, especially gold. 

I can only assume that there is a way to pour exact amounts, but if it was easy, they wouldn't die strike small ingots, they'd pour them. Dies are killer expensive, but the expense pales in comparison to the effort that is required in pouring specific weights. 

I'll gladly eat my words if anyone can provide evidence that I'm wrong. Otherwise, you're far better off to put your energy where it can make a difference. Don't spin your wheels on something that isn't important. There is nothing wrong with ingots that vary in weight-------you simply price them according to content. Were it not for the steak of perfectionism that has plagued me (having worked as a toolmaker), I'd have been ecstatic at the quality of my ingots. Only perfect is good enough when you're crazy, the way I am. 

Harold


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## goldsilverpro

No one can pour exact weight ingots. If you look at some of the silver bars on the market, you'll see a ground area on one end. They make them slightly overweight and grind off a bit to hit exactly 10 oz, 100 oz, etc.

When I cast silver bars, I used two piece "book" molds made of graphite. One piece had the depressions and the sprue holes. The other piece was a flat plate. They were held together with c-clamps and you poured through the sprue holes. If the silver was poured right and if everything was at the right temperature, the gases were all expelled up through the sprue hole and the bars were mostly smooth and flawless. I found that smoking the molds resulted in the best appearance. The sprues were then sawed off. The bars were weighed and the weight, after rounding down, was stamped on the bars. For example - 10.17 tr.oz.


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## lazersteve

GSP and Harold (or anyone else),

Could you provide me some specifics on pouring a series of 10 ounce silver ingots. I have a furnace and two factory made iron molds.

I'm interested in details on temperatures of the mold (warm or hot), fluxing (if required), how to get a smooth finish on the ingot, and any other tips you may have.

I will be pouring a series of 10 ounce silver ingots in the next few weeks and it would be nice to have your advices to save me any gotchas you two have learned from your own experiences. I plan on posting a video of a pour or two once I have the process down pat.

Steve


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## goldsilverpro

Steve,

Since Harold used cast iron molds more that I did, he could probably give you the best advice. As I said, I always used the "book molds" for silver, but I can't remember where I bought them.

I know that, in an open mold, it will be more difficult to make attractive silver bars than gold ones. I would definitely smoke the molds with acetylene.

The top surface is the problem. To put a smooth surface on gold bars, they hold a wide spread out torch on the top surface, immediately after pouring, until the bar solidifies. It kept the surface molten for a longer period of time. A company I worked for used something similar to a propane brush burner. Of course, this was for big bars. The smaller bars are going to want to chill much faster.

The temperature is going to be critical, both on the melt and the mold. The hotter the silver, the more oxygen it will absorb and expel.

If you flux (borax), remove the slag with a carbon rod before you pour.

BTW, are you using a torch or a furnace? If a furnace, what style?

Graphite book molds are easy.

Practice! Practice! Play with it.


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## lazersteve

GSP said:


> BTW, are you using a torch or a furnace? If a furnace, what style?



I have two small (9"x9"x"9) box furnaces with a 3/8" hole on top and a 3/8" peep hole in the front. They melt gold and silver very easily in an hour or less. I tried a few test pours with the silver in graphite and could not get a smooth surface. I did not use any flux at all and the mold was atop the furnace vent while the metal melted. The color of the silver was a brilliant white, but the surface was pocked with air bubbles.

I have casting gold bars down with the furnace, they cast so much easier when the entire dish is white hot. I will never use the torch to cast gold again. The finish on my gold bars is beautiful. I cast them into a ingot shaped graphite mold that has been well sooted that sits atop the furnace vent hole while the metal comes up to temperature.

I tried to add a block of graphite in the interior of the furnace as per Loewen's book (pg 136), to keep oxygen down and it helped on the melt, but when cast the bar quickly absorbed oxygen. He mentioned placing the graphite (carbon) directly in the crucible with the silver, but I am hesitant to do that since I've spent so much energy purifying the silver. Perhaps I can try a lower temperature on the melt?

I was also hoping that I may be able to insulate the surface of the ingot from the O2 with some sort of flux coating that could easily be removed once the ingot cools. I will look at making a graphite book mold as I have lots of hard graphite blocks.

Thanks GSP,

Steve


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## qst42know

In this video you can get a short look at the burner they play on the top of their ingots. The tops look glass smooth.

http://www.youtube.com/watch?v=nQ37SFKahc0

I would guess a large propane torch with a gentle flame would accomplish the same thing.


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## lazersteve

All,

I just located this pdf on casting silver ingots:

Casting Silver Ingots

Thanks for the video also.

Steve


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## Oz

I am guessing you are using a gas furnace of some sort. For silver I am building an electric furnace (not induction)so I can place some sacrificial charcoal on the floor of the furnace to consume the oxygen present once the door to the furnace is closed. The charcoal should last as little oxygen will enter the furnace while melting. The hotter you have the melt the more oxygen it can absorb even in going from furnace to mold. Just some thoughts.


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## lazersteve

Oz,

Unfortunately, I am using electric furnaces for now. 

When I used the hard graphite block to absorb the O2 from the furnace it rapidly caught fire and was about 2/3 decayed after the melt. I was very surprised at the reaction of the graphite while it was in the furnace. I have used the same graphite to make gold molds which have never even showed a hint that they were used as such (zero decay). These same types of graphite blocks show no signs decay when used in numerous electrolytic reactions.

I have a carbon rod I may try on my next silver melt.

I'm also going to cover the top of the silver ingot quickly with a large piece of the hard graphite after it is poured to reduce the exposure to air while cooling.


Steve


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## Lou

Steve,

I know I posted somewhere on this forum a piece on crucible casting silver, in particular the use of a graphite block which sits upon the crucible filled with the silver you are melting. The block oxidizes on the inside of the crucible just above the melt, forming carbon monoxide. This does not react with the silver and is not absorbed into the melt. Silver's affinity for absorbing gases is a function of both time (how long it sees atmosphere) and temperature (at what temperature it is held at). If you are really trying to preclude oxygen, then you can lute the graphite on to the top. 

As for controlling solidification, I am positive that I mentioned that one should have the mold quite warm (but not overly hot). In the case of an open face cast iron mold, it must be sooted and of sufficient draft to withdraw the ingot (by draft, I mean no under cuts, and no really sharp corners). The key to controlling solidification is by putting the hot mold in an insulating medium--perlite is what I have used. For polishing the surface and preventing spitting, you need a slightly rich fan flame that is rather diffuse. If one has any skill with sheet metal, it is a triviality to make a burner tip; these tips can also be purchased commercially.

As far as casting temperature goes--that depends on how thick the bar is. The bigger the bar will be, the lower the temperature your silver or gold may be cast at. Thinner bars generally need higher temperatures so that the metal has less surface tension to fill the mold, and moreover, more heat so it has a longer cool down period.

I might also have mentioned the graphite trick once before to Oz in private communication.

If the graphite block is rapidly oxidizing (let me warn you: a wispy light blue flame is strongly indicative of CO), then you are letting air into your furnace, or it has a leak.

You will never cast exact weight ingots by skill--it will happen in a random spread, some over, some perhaps under if one is not careful, but very rarely, one will be spot on in its mass. 

I am a big, big proponent of what Chris suggests--getting a very fine grain, hard graphite block and having it machined into a multi piece mold (or bank of molds). There was a proprietary, nonstick coating (I think it was boron nitride? the name escapes me at the moment) which was meant for spraying onto graphite molds to prevent oxidation and improve surface finish...I haven't used it in a long time, mainly because it is very expensive. I wish I could remember the name.


Lou


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## lazersteve

Thanks Lou your post helps immensely.

Steve


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## Harold_V

goldsilverpro said:


> I would definitely smoke the molds with acetylene.


The same smoky torch played on the surface of the silver immediately after casting will eliminate spitting and crabbing of the silver. The soot is burned away, absorbing the liberated oxygen, and the flame, which should have a little oxygen introduced, slows the cooling of the ingot so it can cool from the bottom up. That is an important step in achieving a reasonably flat surface. Mold should be preheated as hot as is possible without igniting the blackened surface. 

Beyond that, I had no secrets. I hated pouring silver ingots. Too much time spent on something that had so little value. 

Harold


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## goldsilverpro

The 10 oz "book mold" I used had 5 depressions and 5 sprue holes. The depressions were lined up in a row, side-by-side. I can't find them on the internet. An open 10 oz graphite mold, with any number of side-by-side depressions, could be easily converted to a book mold by carefully cutting a sprue with a round file. I would guess the sprue holes were about 1/2-5/8" wide where they joined the bar and about 3/4-1" wide where they exited the mold - funnel shaped. The cross section of the sprue holes were a half circle. The mold is then covered with a flat sheet of about 1/2" graphite and clamped together gently with 2 c-clamps.

When fire assaying fine silver, the beads spit violently and formed eruptions when cooled and silver is lost. This is solved by placing another very hot cupel on top of the cupel holding the bead, immediately after removing from the furnace. The two cupels, stacked together, are allowed to cool for about 5 to 10 minutes - no peeking. The result is a very smooth silver bead.


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## lazersteve

All,

Over the last four days I tried three different mold configurations, several preheating techniques, and eight pours before I achieved a decent looking ~10 oz. silver bar. 

Here's a shot of my eighth and best try:







I poured the same silver so many times that I ended up losing some weight so the bar is only 293 g instead of 311 g, but I'm still pretty excited about it. I also ended up with a slight bit of contamination on the surface of the bar.

This one was just to get the hang of the bar casting process and to determine the best mold for my set up. After trying the store bought iron molds for three attempts, I quickly realized the cast iron was not going to give me a shiny surface, even with heavy soot and external heating on the pour.

Open top, shallow graphite molds exposed too much molten silver to oxygen and wart up quickly as do long narrow horizontal graphite molds. Even with a continuous propane flame during pouring the bars made with these mold configurations all absorbed Oxygen rapidly.

Oxygen absorption was a major factor that lead me to a good homemade graphite mold design. I finally realized that the best way to minimize oxygen absorption was to pour a vertical bar that had minimal cross sectional area at the top (just as GSP had suggested:wink. Finally I added external heat and a graphite cover to reduce the exposure time of the molten melt to the air. It's very tricky for a single person to switch from pouring a white hot crucible to covering the top of the mold quickly, especially with bulky aluminumized gloves on.

The right end (the top as it was poured) of the bar in the photo did slightly absorb some oxygen, but the top still remained solid, without a pipe or warts. The sides turned out mirror like aside from a few surface imperfections from the mold. The edges were all very clean, sharp, and square along the length. I removed some flashing (excess material) from the top of the bar. The flash appeared as a result of oxygen absorption as I was covering the hot melt in the mold.

Another thing that I learned was that it is very important to clean the graphite mold between each pour. The silver leaves a fine grayish white powder on the inside of the mold that builds up after a few pours.

I think my mold cold be a little hotter also. I'm using a combination of flat top single burner to heat from the bottom and a over sized propane torch to heat the mold from the top. It almost seems like the propane is accelerating the oxygen absorption, but I can not be certain. If anyone knows for sure, that would be great. Any recommendations on a reliable preheating method for graphite molds would also be helpful.

I'll post photos of the other bars once they are done.

Steve


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## qst42know

lazersteve said:


> It almost seems like the propane is accelerating the oxygen absorption, but I can not be certain. If anyone knows for sure, that would be great.
> Steve



Steve 

You may have to tune your propane torch. This is a large roofers torch that runs straight from the tank with no regulator 150k BTU if I remember correctly. The combustion air is syphoned through "as cast openings". I found a piece of thin walled tubing that fits this particular torch well enough to adjust the air it is able to draw. It helps on this particular torch as the mixing chamber is very short. It's not as easy to tell lean and rich with propane as it is with acetylene but some adjustment can help.


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## qst42know

Steve

If you are using EDM graphite be certain it is not the copper impregnated type. Not all graphite is created equal. I have run into this with motor brushes.

http://www.moldmakingtechnology.com/articles/030703.html


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## lazersteve

Thank you, but I'm certain the graphite does not contain copper.

Steve


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## Lou

Steve, your graphite starts to noticeably oxidize above about 900F. Heating your mold can be done by resistance or by placing it on a hot surface. It should not be heated with a torch.

Graphite works well, but it's fragile, prone to decay, and gives somewhat limited use. It can be machined to high tolerances, but it is of small importance when a little bit of the mold is lost after multiple heat ups.

As I said, perlite is your friend. It helps control solidification rates. Steve, remember to let the silver cool in the mold til it is below red heat. If you open it up too soon, your graphite will oxidize. 

Lou


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## Anonymous

I just joined today and this is my first post. I have virtually no experience in the many aspects of gold refining, but with a beginner's bravado I don't see any logical reason why my method would not produce an ingot of exact weight.

First cast your ingots as close to the target weight as is feasible for you. Then use a scale to get the exact weight of each ingot, adding gold leaf or carefully filing as needed to reach the target weight. Lastly, place the modified ingot back into the mold and remelt; since there is no pour involved there is no extra or missing metal to vary the weight. 

To introduce myself, I am a self employed coining die engraver and will be following the forum to learn as well as to try to answer any questions regarding making dies, coins, or custom ingot molds, etc.


----------



## leavemealone

Let me take the opportunity to be the first to welcome you to what I call "Our little slice of heaven."This forum is dripping with experienced and corteous people that will tirelessly help and it sounds like you will fit right in.This is the Guided Tour Link. http://goldrefiningforum.com/phpBB3/viewtopic.php?p=6873#6873 It will help steer you and answer some questions you may have.Have fun,
Johnny


----------



## Harold_V

diecutter said:


> Lastly, place the modified ingot back into the mold and remelt; since there is no pour involved there is no extra or missing metal to vary the weight.


That won't work. Full stop. One does NOT melt in an ingot mold. The reasons are numerous. 

Welcome to the forum. Please take advantage of those of us that have years of refining and casting of precious metals to our credit. 

Harold


----------



## goldsilverpro

Welcome,

A sheet of gold leaf weighs about .012 grams. It would take a bunch of them to a difference. Also, they have rouge on them. I have seen a lot of 100 oz silver bars cast in book molds that have obviously been ground on one end, at the sprue, to reduce the weight.

Unless you know something that we don't, I don't think you'll have much luck melting directly in a mold. I know you can't do it in a graphite mold because it will soon fall apart. Maybe Harold can clue us in on what would happen with a cast iron mold. Maybe a tantalum mold in a vacuum, using resistance melting, would work.

The best way, as you must know, would be to use a coining operation.


----------



## Anonymous

I should have figured it could not be that easy. I was basing the possible success on the fact that the Kerr Electro-melt furnaces and the large vacuum furnaces sold by Rio Grande both use graphite crucibles which are quite durable for that use. The fact that the metal does not solidify in the crucible (at least not intensionally) probably is the reason for their durability.

Maybe if the sides of a graphite ingot mold were highly tapered it would make the mold more durable as the ingots cooled? I saw a demonstration by the Royal Canadian Mint of the entire process used to create their gold coins. They pour the refined gold directly into preheated cast iron ingot molds (50 # ingots if memory serves!) that are lightly oiled. From there the ingot goes through a series of rollers before blanking.

I guess the only sure way to be exact is to strike a planchet or ingot blank that has been already adjusted.


----------



## qst42know

Graphite oxidizes away. Once you bought the furnace they sell you many crucibles over it's life time.

Kinda like Gillette giving away the razor handle and making it up on blades.


----------



## Harold_V

diecutter said:


> I should have figured it could not be that easy. I was basing the possible success on the fact that the Kerr Electro-melt furnaces and the large vacuum furnaces sold by Rio Grande both use graphite crucibles which are quite durable for that use.


They may present the appearance of being durable, but they aren't. Because the temperatures involved are well above the combustion point of carbon, they burn away rapidly, primarily from the shoulder upwards. That's one of the reasons they provide a cover, which limits the exposure to oxygen, but not enough to be totally effective. 

When the furnace is up to heat, even for melting silver, there is a visible flame coming off the graphite around the rim. Failure of the crucible body isn't the problem, the problem is the top burns away such that the crucible is no longer supported by the rim, and there is no pouring spout to allow the crucible to be emptied in a safe fashion, where the discharge is desired. 

I went so far as to coat the top of a crucible with a refractory wash in an attempt to extend the useful life of the crucible, all to no avail. It lasted longer, but not significantly. In the end, the expensive (at the time) furnace was relegated to a shelf in my storage room, never to be used again. They clearly are NOT a good idea.



> The fact that the metal does not solidify in the crucible (at least not intensionally) probably is the reason for their durability.


As stated, above, they are not durable. The typical foundry crucible is far more durable, being made of graphite AND clay, which protects the crucible to some degree. They are also made of silicon carbide, which is far more stable. 



> Maybe if the sides of a graphite ingot mold were highly tapered it would make the mold more durable as the ingots cooled?


That's not an issue. Gold contracts upon cooling, it doesn't expand, so an ingot is inclined to end up loose, assuming it isn't keyed to the mold by lack of draft, or from undercutting by oxidation (graphite mold). 

Melting in a metallic mold would be a horrible idea. Assuming one could use cast iron, remember, it has two properties that are less than desirable. One of them is that it is very poor in tensile----and subject to thermal shock. That's part of the reason it's so damned hard to weld. The other problem is that iron is readily dissolved in molten gold. You not only would struggle with your gold soldering to the iron, but you would suffer contamination of the pure gold from dissolution. 

While I am not the least bit familiar with tantalum, I am of the opinion it, too, would be a huge mistake. It may not fracture from thermal stress, but it surely would be problematic in the way of contamination, and most likely soldering. 



> I guess the only sure way to be exact is to strike a planchet or ingot blank that has been already adjusted.


That is my opinion. Certainly, I'd avoid any ingots that had signs of having been altered---by any method. Shaving coins used to be a way of stealing----when the value of the coin was in the metal contained within. That problem was addressed by reeding the edges of coins, or otherwise making them such that any removal of material was obvious. It is for that reason that I never altered any of my ingots. They were always left as cast, although I did make attempts to create a smooth surface by controlled cooling. That appears to be common practice and leaves no damage to the surface of ingots. 

For the record, casting ingots is not easy, not if you desire attractive ingots. Gold is far easier to cast, if for no other reason, oxygen isn't a problem as it is with silver. 

I own several 100 ounce silver ingots made by one of the major refiners. They are die struck, which boggles the mind. I can only imagine the tonnage required! Very nice, they are :!: :!: 

Steve commented that his graphite molds slowly formed a gray surface, which must be removed. 

Yep, that they do. That's the result of the adsorbed oxygen being consumed as the silver solidifies. It can be limited, but unless one is able to melt and pour in an inert environment, it can't be eliminated. An inert atmosphere induction furnace would be the answer. Doesn't everyone have one of those in their garage? :lol: 

I wouldn't use graphite for a mold, not under almost any circumstance, but then I also had the ability to produce my own cast iron molds. Nothing rivals a nicely blackened iron mold, especially if the iron is ductile instead of cast gray iron. 

Harold


----------



## goldsilverpro

Harold said:


> While I am not the least bit familiar with tantalum, I am of the opinion it, too, would be a huge mistake. It may not fracture from thermal stress, but it surely would be problematic in the way of contamination, and most likely soldering.



You're right, Harold. The gold would stick tight to the Ta. When I mentioned using Ta, I was using some ridiculous sarcasm. I knew it wouldn't work and probably shouldn't have said what I did. I have refined a few batches of Ta boats that were used to evaporate gold in a bell jar. The gold was always stuck tight to the Ta.


----------



## g_axelsson

I have a bell jar with a vacuum system and electrical heaters. It is a vacuum evaporator for adding metals or carbon to a sample before observing it in a electron microscope.
I got it for that purpose but I always toyed with the idea of creating a small graphite boat and melt silver and gold in vacuum via resistive heating the boat.

When I get the system up and running I'll make some tests. Right now it is sitting in my storage behind a couple of boxes full of electronic scrap. I'll have to go through that first. Then I also might have something to melt. :lol:
Don't expect any results before the end of this year.

/Göran


----------



## Lou

I use those sputter systems quite frequently. I think you'd have to rework the power supply though :-/


----------



## g_axelsson

This is not a sputtering system, it is a carbon evaporator. It has a power supply capable of delivering 300A of current into a carbon rod (I think that was what the meter could show).
To deposit gold and other metals you use a small tantalum boat, molybdenum boat or wolfram wire and heat the metal until it evaporates.

But I haven't used the system yet, I got it last year but haven't had the time to set it up yet so I might be wrong in how it is used.

I would like to have one of those nice bench top sputtering systems. This beast is a 200 kg machine with vacuum pumps and transformer. Sputtering systems uses RF and ionized gas to knock gold atoms off a target and deposit it on the specimen.
I guess that is what you are talking about as you call it a sputter.

To rework the power supply shouldn't be too hard if I need to. I have rebuilt my TEM from single phase supply (needed 20A 220V) to run off three phase power. If I had gone past 16A the fuse would have blown.

My pet TEM project, sorry for the missing pictures. I'll add it back asap, I had a server crash a month ago .

/Göran


----------



## Lou

Göran,

I'm sorry that I didn't read your post more clearly--I just assumed that you had found an old sputter setup and didn't know how it worked :-/ I know exactly what you are speaking of now. In fact, several weeks ago I was making an experiment that required just such a technique  

I also am messing around, but with me it is an SEM. I do occasional (S)TEM, AFM, etc at work, so maybe we can have some conversations on your microscope!


----------



## Exibar

Wow, I just have to say that you guys, Harold, GSP, Steve, etc are certainly a wealth of knowledge!

My hat goes off to all of you for sharing your knowledge with us youngins! ok, I'll bet most of us are middle-aged (I'm 40)... but my knowledge on this stuff certainly qualifies me as a youngin compared to you folks!

thanks again guys!
Mike B


----------



## grainsofgold

Lou said:


> Göran,
> 
> so maybe we can have some conversations on your unit!




You might consider editing your choice of words Lou 8)

Instead of trying to pour 1 oz ingots I would suggest coining them or rather die striking them from a known size planchet of 1 oz. There are many mints that are very slow right now that will take your gold and make a custom coin or ingot to your specs and design- Way less than trying to buy the equipment and learn the process yourself.


----------



## Lou

Well that explains why he never replied. I suppose when you tell someone you want to have a conversation on his unit and you're not an endocrinologist, it tends to send the wrong message.


----------



## g_axelsson

Well, I never replied as the forum was down for a while and then I forgot about it until now. Actually I wrote a long answer but I couldn't post it then.
Right now I'm late for a job and the vacuum evaporator is buried behind a ton of computer scrap. It will be a couple of months before I can even get to the front panel to read some data of it.

Now I have to run to the job... too much fun things to do and so little time. See you later! :lol: 

/Göran


----------



## adrag10

Ok Harold, here's my attempt.

You melt the gold slightly over weight and cast the ingot. Then file the ingot to the desired weight. Then run the torch over the file marks to blend them in with the rest of the ingot. An alternative method would be to polish or buff the marks away though it would much more time consuming and you run the risk of going underweight. 

So what do you think? Do I win the prize? Is there a a prize? There should be....like a free bag of cookies or something.

Al


----------



## qst42know

No cookies for you Al. :wink: 

An altered surface would be an immediate suspect of tampering.


----------



## butcher

I think Quest4toknow just ate all the cookies.


----------



## Harold_V

I agree. No cookies. 

Running a torch on a gold ingot to blend marks works about as well as a pig on stilts. 

Harold


----------



## Barren Realms 007

Harold_V said:


> I agree. No cookies.
> 
> Running a torch on a gold ingot to blend marks works about as well as a pig on stilts.
> 
> Harold



What??? Now you are going to start about the pigs. :roll:


----------



## Harold_V

Barren Realms 007 said:


> Harold_V said:
> 
> 
> 
> I agree. No cookies.
> 
> Running a torch on a gold ingot to blend marks works about as well as a pig on stilts.
> 
> Harold
> 
> 
> 
> 
> What??? Now you are going to start about the pigs. :roll:
Click to expand...

Barbequed, they're delicious. Second best only to lamb. :lol: 

H


----------



## Barren Realms 007

Never had lamb BBQ'd. I'll have to try that.


----------



## erogers36

Harold_V said:


> viacin said:
> 
> 
> 
> Why refine at all? Why not simply buy scrap from Point A and sell it to us refiners at Point B for your profit?
> 
> 
> 
> It all depends on one's objective, eh?
> 
> It may come as a surprise to readers, but I refined gold for more than nine years before I sold as much as a grain. My interest was not in making money, but in owning gold. I already had a good income and had enough money to cover my needs, which are small. I do not buy a new car because the neighbor does. I dictate the terms of my life, I do not allow his choices to influence mine.
> 
> When I started refining, it was illegal to do so without a federal license. Screw them, I said to myself. That sounds like way, way, way too much government control. I'll just figure this thing out on my own and refine, storing gold for my retirement.
> 
> By the time I started selling gold, I was well recognized as a gold refiner and had a strong following. All restrictions on processing and possessing gold were eliminated on Jan. 1, 1975, which allowed me to be vocal about my hobby-----a hobby that was virtually unheard of because of previous regulations. I was in the right place at the right time for a business to blossom, although that was never my intention.
> 
> Selling for spot was no big deal, a simple phone call to given customers and it was gone. The customer got a good deal because they bought for spot----which they, otherwise, were unable to do.
> 
> So then, the objective of each individual is what matters.
> 
> I have little patience with the guy that thinks he will stride into a situation, grab all the values and dump them in the lap of a refiner, making a killing in the process. These morons usually do little more than muddy the water for those that have good intentions. If any of the readers of this forum think they're going to skin a fat lamb by dealing in precious metals, they're in for the surprise of their lives. The precious metal market is exceedingly fickle. I sat watching the gold market for more than 20 years, with many of them with gold in the $300 arena. In those twenty years, I saw it run up to $500 and fall back, often well below the price of production.
> 
> You doubt my comment about a fickle market? How then would you account for the price of rhodium----which was over $10,000 not too long ago?
> 
> Bottom line? If you are interested in being a refiner, it is important to serve the needs of your primary customers. If they are people that deal with ingots, that's what you must provide. If you rely on a second or third party to provide them, your chance of survival is small---for you'll make little money, if any, and if you cheat the customer to insure profit you won't last long enough to make it worthwhile. One unhappy customer can do more damage to one's reputation than can be healed with hard effort and a prolonged period of time.
> 
> The choice is yours. Become a refiner, or find a different way to find entertainment. Or------simply stay the course and refine for your own pleasure, with no idea in mind of making profit. That way anything that comes from your activity can be looked upon as having made a dime.
> 
> An added thought; the idea of hitting garage sales, flea markets and all the other sources you can conjure is a waste of time. That's not to say you can't, and won't, find the odd bit of precious metal. You will, but you can't make it a living.
> 
> I snickered time and again as I talked with one of my customers, a prospector that had undying devotion. I accumulated more gold in two weeks than he did in a year, simply be refining for others for a percentage. There's nothing like going out looking for gold to put in focus the reason why it sells for the price it enjoys. It's damned hard to come by, be it via e scrap, where you put in a huge amount of labor, or by prospecting, which may *never* pay dividends. You have to use wisdom to make this thing work----with the niche market Lou spoke of the biggest part of success.
> 
> Harold
Click to expand...



Wow is all i can say. I am traped im my house here in Texas most months of the year.
and it is because of my health . there for i look for things to do while it is hot out side . gold just sould like something to take up time consuming for me to play with to eat up the time and reading your post tells me that you have done your time and know what you are talking about . Im a nube so if you resond back it take time for me to fine it lol 

Eric


----------



## Harold_V

Eric,
If you have time on your hands, and a source of e scrap, you may just be the rare candidate I would encourage for making a few bucks, or at least putting away a few ounces of gold. Nice thing about it is you can watch TV or listen to music as you dismantle old gear and accumulate lots that will be processed when you can venture out of doors. Better yet, you may even find a small pump shed sized building that can serve as your tiny refinery, and you can work there year round, assuming you can cool the place in the summertime. 

I don't normally encourage folks where e scrap is concerned, assuming they have a business in mind. You can work yourself to death refining e scrap and not make much money, but for a guy that has time on his hands, it's a great way to spend a few days each week. Sort of gives you something to get up for in the morning, and there's nothing quite like holding that first button of gold, particularly if you've never held elements that are heavier than lead. 

Remember, of all the elements we accept as metals, all are various shades of silver in color. Gold and copper stand alone, each having their own unique color. You will work with both of them in refining. 

Study the forum, and get a copy of Hoke's book. Be patient. None of this comes fast and easy, although none of it is difficult once you understand the processes involved. If you can follow directions, you should be able to refine to perfection. 

Luck!

Harold


----------



## Oz

That is spot on Harold. 

Refining e-scrap is a loosing proposition as a business unless you are doing large quantities. Having said that I will run electronics if I get the material for free and have no other work that pays at the moment. With the economy as it is it is better to make a $ an hour than to make nothing watching cable TV. When all else fails, just stay busy.


----------



## goldsilverpro

With only one exception that I can think of, I can see no way that anyone could profit from refining e-scrap by using *any process* that would chemically dissolve the base metals. There are many reasons for this - huge waste generation, huge chemical usage, fume control, large amount of equipment and space needed, labor, etc. The exception is running high grade materials, such as old, all-gold CPU packages or CPU package lids that contain gold solder. At this state of the economy, I would define "high grade" as anything that was worth at least $200-$300 per pound in gold content.

Professional refiners *NEVER* dissolve the base metals in e-scrap except for the exception I noted above. They know better. They incinerate everything and then ball mill and screen the ash. The metal, which doesn't go through the screen, is melted and cast into bars. Both the pulps (the ash that goes through the screen) and the bars are sampled, assayed, and shipped to a primary copper smelted for refining.

Many refiners strip the gold plating on certain materials using cyanide and an oxidizer. Thus far, I know of no other substitute for cyanide that can be used in this way. However, for certain, very limited types of parts, the sulfuric electrolytic cell can be made to run profitably.


----------



## glorycloud

Sad but true. E scrap takes a lot of labor to process and refine.
Luckily for some of us, we get the stuff for free as part of what 
we do. For me, that is selling computer equipment on the for profit
side and giving away PC's on the 501C3 side of what I do. Both sides
feed the escrap pile. My customers are grateful to have me haul
off there "junque" because they trust that I will deal responsibly
with the material for them. I get donated equipment as well and
what I can't use internally, I break down for parts or recycle.

All that means is that I get the material "for free", so to speak.
I invest my time and effort to pick off what I want from the
pile of escrap and sell the rest to the refiners for them to process.
So, for a little time invested, I get to dissolve some base metals
and get a few nice shiny gold buttons on occassion. 8) 

This forum has provided so much information to someone like
me and I am grateful for what you all offer so freely - good practical
advice! Without that advice, I would be sending all my "golden goodies"
off to ebay or the refiners for sale and where is the fun in that? :lol: 

Having said all that, if I weren't getting the escrap for free it would
surely be difficult to justify the time, effort and materials required
to tinker around with this stuff. I would wager that many who find
this forum useful have seen the gold glittering on a scrapped out 
computer and have said gee, I might not quit my full time job to do
this but I will at least safely give it a try and see what happens.
After seeing what it takes to get .75 grams of gold they go away.
Lesson learned for them but hey maybe they can take something 
positive from it like I have: It's a hobby and I have fun doing it. 8)


----------



## Oz

goldsilverpro said:


> At this state of the economy, I would define "high grade" as anything that was worth at least $200-$300 per pound in gold content



Even when free I only run material that has been high graded first. 

This is one of the reasons I feel silver is under priced, it is thrown away due to the cost of recycling unlike gold. Silver spot prices will ultimately be pushed up at least to the point that it is economical to recover it from e-scrap in my opinion. For some time more silver has gone to the landfill than has been mined in that same year. That will end.


----------



## Anonymous

Just a thought Why pour at all why not just use a porceline mold to cast cheap ingots from clay then add gold to the cheap ingots and allow them to fire in a kiln. at the end of the process just break off the clay?


----------



## leavemealone

> Just a thought Why pour at all


I recommend you spend an abundance of time researching what we do here,and the different procedures before making a suggestion like this.



> why not just use a porceline mold to cast cheap ingots from clay then add gold to the cheap ingots and allow them to fire in a kiln. at the end of the process just break off the clay?


Because that is a form of lost casting(similar to lost wax casting),that will never work for what he was trying to accomplish.You would be doing multiple steps,when 1 step would be sufficient.....thats why.


----------



## 19Smitty77

On the very first page, someone mentioned that alterering an ingot by filing on it voids the markings. Totally makes sense. When and if I reach the point of making a freshly poured ingot, My plan was to stamp the weight and kt using something like a leather stamping kit. Is this a sound plan? Pros? Cons?


----------



## Harold_V

19Smitty77 said:


> On the very first page, someone mentioned that alterering an ingot by filing on it voids the markings. Totally makes sense. When and if I reach the point of making a freshly poured ingot, My plan was to stamp the weight and kt using something like a leather stamping kit. Is this a sound plan? Pros? Cons?


That may work, but you can purchase inexpensive stamps intended for makring metals by paying a visit to a Harbor Freight Store. 

The real problem you'll face when pouring ingots is determining a realistic weight, as well as the purity of your product. You should be able to weigh gold to no less than four places after the period. 

You may wish to mark in the metric system, but don't lose sight of the fact that gold is sold by the troy ounce. You would need to get accustomed to using the grain scale when weighing by that method, which is also commonly used in hand loading cartridges for guns. It's very easy to learn. 

Do remember---when working with the troy system, an ounce is larger than an avoirdupois ounce (troy 480 grains, Av 437.5 grains) and a troy pound is smaller than an avoirdupois pound (12 troy ounces = 1 troy pound ---5,760 grains) versus 16 av. ounces = 1 av. pound--- 7,000 grains). In troy, there is common discussion of pennyweights (dwt). A dwt weighs 24 grains, and there's 20 dwt per troy ounce. 

Harold


----------



## 19Smitty77

Thanks Harold!

I'll check into harbor freight like you said. I'm still along way off as I am still gathering jewelry for my first inquartation. I've gotten really excited about this especially after reading the information on this forum!

EDIT: Yep I know a Troy ounce is roughly 31.1 grams. I'm not too worried about 4 decimal places at this point because I'm looking at it from a novice hobbyists point of view. I'm sure though, that once I get into it the drive for perfection will set in LoL


----------



## goldsilverpro

Smitty said:


> I'm not too worried about 4 decimal places at this point because I'm looking at it from a novice hobbyists point of view. I'm sure though, that once I get into it the drive for perfection will set in



The better reloading scales that Harold mentioned weight down to 0.1 grains. That is about 0.0002 troy ounces. If you're using any other type of lesser scale, make sure the the weight that is stamped on the bar is less than the weight determined by the scale you're using. If you're using a 1 or 2 decimal point gram scale, I would reduce the last digit by at least one number. You never want to stamp more than the true weight. Just remember that, no matter what scale you use, the last digit is always questionable, at least by one number.


----------



## 19Smitty77

goldsilverpro said:


> If you're using a 1 or 2 decimal point gram scale, I would reduce the last digit by at least one number. You never want to stamp more than the true weight. Just remember that, no matter what scale you use, the last digit is always questionable, at least by one number.


Oh wow, good point, I never considered breaking the law unintentionally. That's an entirely possible scenario.


----------



## Harold_V

19Smitty77 said:


> goldsilverpro said:
> 
> 
> 
> If you're using a 1 or 2 decimal point gram scale, I would reduce the last digit by at least one number. You never want to stamp more than the true weight. Just remember that, no matter what scale you use, the last digit is always questionable, at least by one number.
> 
> 
> 
> Oh wow, good point, I never considered breaking the law unintentionally. That's an entirely possible scenario.
Click to expand...

It's not so much breaking the law as it is screwing up your credibility. No one will complain if you give them a tenth of a grain too much, but short them the same amount and you're labeled a crook.

When I refined, virtually 100% of the gold I produced was returned to the customer, less my percentage. When I'd mark the package, I always rounded down, and marked to only two places. That way, when they weighed the gold, it always weighed more than the package mark. You'd be surprised how many guys would call me to tell me I had given them too much gold. They check, and they expect fair treatment. 

When a call came, I'd just chuckle and tell them that what they got was rightfully theirs, and to enjoy the spoils. 

Credibility in refining is everything---assuming you expect to build a viable business. 

Harold


----------



## joem

A grass roots back yard gold person might use a metal scale, zero out the mold and pour until 1 oz is reached.
just my thought
joe


----------



## jimdoc

The gold cools too quickly to make that work,
without luck on your side.It would be harder
than it seems.

Jim


----------



## Anonymous

> A grass roots back yard gold person might use a metal scale, zero out the mold and pour until 1 oz is reached.
> just my thought


Thats why they would be called a "grass roots back yard gold person"



> The gold cools too quickly to make that work


The gold "cooling",is not the issue.The issue is getting an accurate weight,which can not be accomplishd with a traditional scale,and certainly not by tearing off the weight of a mold and pouring.A single drop of liquid gold could weigh as much as a half of a gram.When you are trying to weigh out to the 4th decimal place this cannot be accomplished
Countless accurate ideas have already been suggested on this matter


----------



## joem

I like giving a bit more. It keeps you credible. and why worry about the weight any buyer will weight it anyway and you should be paid by the price per weight.
joe


----------



## MargueriteMingorance

Harold_V said:


> Leviticus7 said:
> 
> 
> 
> I am really new to this, and still learning the termanology.
> 
> 
> 
> You have far more than terminology to learn. You have yet to discover that the suggestions you provided
> 
> 
> 
> My idea is when you get ready to melt the gold, add a little extra to compinsate for the amount that is left in the crucible after you finish pouring so that you make sure that you have enough. Also, you could take your empty ingots, place them on a scale, and zero the scale with the ingots on it. Then pour the gold into the ingot until the scale reads 1oz. If you have 4 spaces on one ingot, then pour the gold in the first space until the scale reads 1oz, and then pour the gold into the second space until the scale reads 2oz(1oz in the first space and pouring the second ounce) and so on.
> 
> Click to expand...
> 
> are worthless.
> 
> Yes, they make sense on paper, but in practice they do not, nor will they ever---not pouring by hand. If you are familiar with a grain of gold, and how small it is, and consider a grain equates to 1/480th of a troy ounce, and an ingot is weighed to 4 places, a tenth of a grain effects the weight of an ingot by .0010 ounce. You simply can not control the pour to that degree of precision, nor will gold cooperate with tipping miniscule amounts.
> 
> I'm not trying to be rude----I'm just trying to have you understand that you are dealing with infinitely small units, all of which are very important in the way of credibility. Ingots must weigh what they are marked, and establishing a desired weight is likely to be beyond your ability. You pretty much have to settle for random ingots unless you pour them heavy, then adjust their weight before die striking. That would create a uniform surface. The alternative is to roll gold to a specific thickness, punch a planchet, which would be adjusted for weight, then die struck. You would fail miserably at pouring ingots of a specific weight, although you will hit the occasional one. It happened for me, but rarely. It was not predictable in spite of considerable effort.
> 
> Harold
Click to expand...


How about...

Assuming a graphite mold, using an electric furnace and an inert atmosphere...

Weigh out 1 ounce exactly of shotted gold, pour it in the mold (it's okay if it heaps up some) then pop the whole thing into the furnace and melt it.


----------



## lazersteve

Check this thread:

Can you melt in the mold?

Steve


----------



## MargueriteMingorance

Harold_V said:


> diecutter said:
> 
> 
> 
> I should have figured it could not be that easy. I was basing the possible success on the fact that the Kerr Electro-melt furnaces and the large vacuum furnaces sold by Rio Grande both use graphite crucibles which are quite durable for that use.
> 
> 
> 
> They may present the appearance of being durable, but they aren't. Because the temperatures involved are well above the combustion point of carbon, they burn away rapidly, primarily from the shoulder upwards. That's one of the reasons they provide a cover, which limits the exposure to oxygen, but not enough to be totally effective.
> 
> When the furnace is up to heat, even for melting silver, there is a visible flame coming off the graphite around the rim. Failure of the crucible body isn't the problem, the problem is the top burns away such that the crucible is no longer supported by the rim, and there is no pouring spout to allow the crucible to be emptied in a safe fashion, where the discharge is desired.
Click to expand...



Okie doke. So, need to use something other than graphite, or metal, for the mold, right? What about fused quartz? That's like glass, right? It should give a very smooth finish.

Since you're reheating the gold in the mold, you can bring the temp up slowly, and then let it cool slowly. This would avoid thermal shocks. After all, that is how glass is anealed. Since the gold will shrink on cooling, it should come out of the mold fine. A mold made of SiO2 won't contaminate the gold, will it?

For silver, could you coat the mold with a dusting of graphite? It would burn away as CO2, absorbing any oxygen. I would suggest oil, but it contains impurities, like sulphur and chlorine, and maybe trace metals.

The melting point of pure SiO2 is 1650C. Melting point of gold is 1065C, silver is 962C.


----------



## MargueriteMingorance

Harold_V said:


> 19Smitty77 said:
> 
> 
> 
> 
> 
> goldsilverpro said:
> 
> 
> 
> If you're using a 1 or 2 decimal point gram scale, I would reduce the last digit by at least one number. You never want to stamp more than the true weight. Just remember that, no matter what scale you use, the last digit is always questionable, at least by one number.
> 
> 
> 
> Oh wow, good point, I never considered breaking the law unintentionally. That's an entirely possible scenario.
> 
> Click to expand...
> 
> It's not so much breaking the law as it is screwing up your credibility. No one will complain if you give them a tenth of a grain too much, but short them the same amount and you're labeled a crook.
Click to expand...


Well, actually, technically, it's fraud. It _is_ breaking the law, at least if you represent that the bar actually weighs what it says it weighs.


----------



## lazersteve

MargueriteMingorance said:


> ...
> Okie doke. So, need to use something other than graphite, or metal, for the mold, right? What about fused quartz? That's like glass, right? It should give a very smooth finish.
> 
> Since you're reheating the gold in the mold, you can bring the temp up slowly, and then let it cool slowly. This would avoid thermal shocks. After all, that is how glass is anealed. Since the gold will shrink on cooling, it should come out of the mold fine. A mold made of SiO2 won't contaminate the gold, will it?
> 
> For silver, could you coat the mold with a dusting of graphite? It would burn away as CO2, absorbing any oxygen. I would suggest oil, but it contains impurities, like sulphur and chlorine, and maybe trace metals.
> 
> The melting point of pure SiO2 is 1650C. Melting point of gold is 1065C, silver is 962C.



Not a terrible idea, but a few points:

1. Quartz will tend to devitrify and decay at elevated temperatures after repeated use.

2. Machined fused quartz is very expensive.

3. Fused Quartz is very brittle and is easily broken if mishandled or dropped. The good thing about quartz is it can go from hot to cold relatively quickly and not shatter like Pyrex or lesser glass.

4. Fused quartz requires special handling considerations to maintain it's continued integrity. 

Here's a usage guide for fused quartz:

Fused Quartz Usage Guide

I can't help but think you would quickly ruin your expensive quartz mold with skin oil, furnace trash, and other contaminates found in the metal and melting process.

If you could over come and/or address the points above, I think you may be on to something, but I've never tried it my self. I own several pieces of quartz ware and they require special attention unless you have deep pocket for buying new quartz equipment. 

The expense of quartz fabrication will typically equal or exceed the already high cost of the raw materials to make the item out of quartz, in your case bar molds. If you have a few extra hundred bucks laying around and want to give it is shot, I for one would like to see the results.

Steve


----------



## T3sl4

MargueriteMingorance said:


> Harold_V said:
> 
> 
> 
> They may present the appearance of being durable, but they aren't. Because the temperatures involved are well above the combustion point of carbon, they burn away rapidly, primarily from the shoulder upwards. That's one of the reasons they provide a cover, which limits the exposure to oxygen, but not enough to be totally effective.
> 
> When the furnace is up to heat, even for melting silver, there is a visible flame coming off the graphite around the rim. Failure of the crucible body isn't the problem, the problem is the top burns away such that the crucible is no longer supported by the rim, and there is no pouring spout to allow the crucible to be emptied in a safe fashion, where the discharge is desired.
Click to expand...


Video footage:
[youtube]http://www.youtube.com/watch?v=-_Dj_DoIHhs[/youtube]

At the surface, carbon monoxide forms. When it reaches cooler air, it burns with a weak blue flame. The erosion rate is pretty serious when the crucible is packed with nice and porous kaowool -- your average crucible may only last an hour, total!

Tim


----------



## Harold_V

Tim,

I've quietly followed your exploits for some time now. Congratulations on your apparent success with the induction furnace. Very nice!

Harold


----------



## MargueriteMingorance

lazersteve said:


> MargueriteMingorance said:
> 
> 
> 
> ...
> Okie doke. So, need to use something other than graphite, or metal, for the mold, right? What about fused quartz? That's like glass, right? It should give a very smooth finish.
> 
> Since you're reheating the gold in the mold, you can bring the temp up slowly, and then let it cool slowly. This would avoid thermal shocks. After all, that is how glass is anealed. Since the gold will shrink on cooling, it should come out of the mold fine. A mold made of SiO2 won't contaminate the gold, will it?
> 
> For silver, could you coat the mold with a dusting of graphite? It would burn away as CO2, absorbing any oxygen. I would suggest oil, but it contains impurities, like sulphur and chlorine, and maybe trace metals.
> 
> The melting point of pure SiO2 is 1650C. Melting point of gold is 1065C, silver is 962C.
> 
> 
> 
> 
> Not a terrible idea, but a few points:
> 
> 1. Quartz will tend to devitrify and decay at elevated temperatures after repeated use.
> 
> 2. Machined fused quartz is very expensive.
> 
> 3. Fused Quartz is very brittle and is easily broken if mishandled or dropped. The good thing about quartz is it can go from hot to cold relatively quickly and not shatter like Pyrex or lesser glass.
> 
> 4. Fused quartz requires special handling considerations to maintain it's continued integrity.
> 
> Here's a usage guide for fused quartz:
> 
> Fused Quartz Usage Guide
> 
> I can't help but think you would quickly ruin your expensive quartz mold with skin oil, furnace trash, and other contaminates found in the metal and melting process.
> 
> If you could over come and/or address the points above, I think you may be on to something, but I've never tried it my self. I own several pieces of quartz ware and they require special attention unless you have deep pocket for buying new quartz equipment.
> 
> The expense of quartz fabrication will typically equal or exceed the already high cost of the raw materials to make the item out of quartz, in your case bar molds. If you have a few extra hundred bucks laying around and want to give it is shot, I for one would like to see the results.
> 
> Steve
Click to expand...


Well, you have a furnace, right? Quartz is glass. So, get a mold made of the quartz mold you want, and buy pure SiO2 sand. Melt a slug of it, and form it in your own (cast iron or steel or whatever) mold. Then you can make all the quartz molds you want. Fire polish the fused quartz (which seems like a fancy term for glass, to me) so you have a smooth finish. Why pay someone else to make your own disposable molds???

Plus, if your quartz mold breaks, just remelt it.

EDIT: turns out fused quartz is just a fancy name for fused silica. Like refining, it is one of those things where it is hard to find information on doing things yourself.

As for making a furnace with an inert atmosphere, that seems easy to me. Get a furnace whose top and doors are air tight. Add some fittings into the bottom (2). One fitting you use to inject helium, which you can buy in tanks. The other is to let interior air out the bottom. Helium is light, it will rise, and force the heavier air out the bottom of the furnace.


----------



## jimdoc

I don't think it is that easy,they would not cost as much as they do if that
could be done easily.

Jim


----------



## Harold_V

MargueriteMingorance said:


> Well, you have a furnace, right? Quartz is glass. So, get a mold made of the quartz mold you want, and buy pure SiO2 sand. Melt a slug of it, and form it in your own (cast iron or steel or whatever) mold. Then you can make all the quartz molds you want. Fire polish the fused quartz (which seems like a fancy term for glass, to me) so you have a smooth finish. Why pay someone else to make your own disposable molds???
> 
> Plus, if your quartz mold breaks, just remelt it.


It appears to me that your post is one of antagonism, not intended to be constructive in the least. Please refrain from such ativity on this forum.

Your comments are not relevant. The melting point of quartz is nearly 1,000°F above the melting point of cast iron. It is roughly 500° above the melting point of steel. Needless to say, your comments have no value, as they simply won't work. 

Harold


----------



## MargueriteMingorance

Harold_V said:


> MargueriteMingorance said:
> 
> 
> 
> Well, you have a furnace, right? Quartz is glass. So, get a mold made of the quartz mold you want, and buy pure SiO2 sand. Melt a slug of it, and form it in your own (cast iron or steel or whatever) mold. Then you can make all the quartz molds you want. Fire polish the fused quartz (which seems like a fancy term for glass, to me) so you have a smooth finish. Why pay someone else to make your own disposable molds???
> 
> Plus, if your quartz mold breaks, just remelt it.
> 
> 
> 
> It appears to me that your post is one of antagonism, not intended to be constructive in the least. Please refrain from such ativity on this forum.
> 
> Your comments are not relevant. The melting point of quartz is nearly 1,000°F above the melting point of cast iron. It is roughly 500° above the melting point of steel. Needless to say, your comments have no value, as they simply won't work.
> 
> Harold
Click to expand...


Well, my tone was intended to be light-hearted, not insulting, and my intent was to be constructive.

I don't know what glass makers make their molds from, but they do make them from something, that can withstand the heat. Find out what they use, so you can make your own fused quartz molds. Just because I was wrong about what substance to make the molds from doesn't mean my comments have no value at all.

Of course, you could use a fired ceramic mold, but glazes often have metals in them, and an unglazed surface wouldn't yield a very nice finish on your exactly one ounce (or any other size) ingot.

Here is a site that sells books and glass making supplies, including stuff to make your own molds to cast your own glass:

http://www.sundanceglass.com/castrefractr.htm

Or, get your glass mold make from tungsten, its melting point is 3420C. Items made of tungsten are typically sintered. Finding an american company to make such a mold seems difficult, but Chinese manufacturers are all over the place. Molds seem to run in the $100-1000 range. They make molds for injection molding of metal.

Chinese industry is working hard to beat the pants off the US.


----------



## Harold_V

MargueriteMingorance said:


> Well, my tone was intended to be light-hearted, not insulting, and my intent was to be constructive.


I'll consider that that is the case. 



> I don't know what glass makers make their molds from, but they do make them from something, that can withstand the heat.


They often use cast iron. The problem is, you don't appear to understand that fused quartz isn't the same thing as glass, including borosilicate glass. Common glass melts at temperatures under 2,000°. Assuming you have the ability to melt quartz, it will be liquid at a temperature in the vicinity of 3,300° F, which would have, long ago, melted the vast majority of metals. 



> Just because I was wrong about what substance to make the molds from doesn't mean my comments have no value at all.


You appear to me to be an individual that gets an idea, puts his head down and plunges forward, ignoring anything that may not be to his/her liking. 

Understand that working with precious metals is an old art---very little is new. Those that have gone before us have discovered what works, and what does not. It's highly unlikely a guy/gal (not intended to be a personal affront) that has no history of working with precious metals is going to make a discovery that revolutionizes basic processing. One is far better served to follow convention, at least until a firm understanding of the problems are at hand, instead of second guessing those that have years of experience and understand the problems well. 



> Of course, you could use a fired ceramic mold, but glazes often have metals in them, and an unglazed surface wouldn't yield a very nice finish on your exactly one ounce (or any other size) ingot.


You're assuming a great deal here. Lets assume, just for a moment, that you can make a ceramic mold, and I'll consider that it may not have to be glazed. Will it have the required thermal shock resistance to withstand having a substance that is in excess of 3,300° F poured to it and not self destruct? Can one, in fact, pour molten quartz? I don't know that it can be poured, and likely can not. 

Harold


----------



## MargueriteMingorance

Actually, fused quartz is glass. "Fused quartz" and "fused silica" are basically interchangeable. It is pure SiO2, which is a fairly high temperature glass, with high thermal resistance because it has a very low expansion coefficient. From what I have been reading over the last hour, it seems to be fairly durable, although it does degrade with time at high temperature, and is brittle.

Glass manufacturers add things like boron and other trace elements for color, hardness, and to lower viscosity (glass doesn't actually melt, as it doesn't have a crystalline form). What you call "common" glass is actually a fairly new invention. The ability to mass produce window glass didn't really happen until the mid-1950's, when the techninque of floating the glass on a bed of molten tin to allow the glass to slump to a flat heated surface became the norm. Before that glass was "poured" onto a metal table, where it slumped and cooled. This left the glass thicker in the middle than at the edges. Before that, it was blown into cylinders, then the top and bottom was cut out and the cylinder slit and opened to make flat panels. It is modern glass making that has mastered adding different substances to control viscosity, making glass more malleable at lower temperatures. Boron doesn't actually affect the viscosity, it protects glass from chemical attack, making it more durable.

Typically, formed glass is either slumped into molds, or a batch of it is heated into a "slug", which is then pressed into a mold. If the silica material is placed into the mold and then fired, it slumps into the mold, so there is no problem with thermal shocks. Glass molds are made from a wide variety of substances, including iron and steel, ceramics, cement, plaster, and various non-refractory metals.

As for putting glass into a ceramic mold, again, you can either slump the glass into the mold with the furnace, heating them together, or you can mold a slug. However, thermal shock should never be a problem, because you can always heat the mold ahead of time.

Here's a bit about different mold types for glass:

http://www.warmglass.com/molds_for_slumping.htm#clay

Here is a company that makes custom glass molds:

http://www.koppglass.com/Mold-Making-and-Design.html

BTW, fused silica can be sintered at less than 1300C:

http://www.faqs.org/patents/app/20080196448

Sintering takes time, a lot longer than it would take the gold for an ingot to melt into the form. As soon as the gold is melted the form can be removed from the furnace and allowed to cool. The gold will shrink, the silica mold won't shrink as much. Pure silica handles temperature transitions well.


----------



## Harold_V

And how much money are you prepared to procure this mold of sintered silica? 

The point I've tried to make all along is that your idea isn't viable. You can toss all the information at me you wish, but the fact remains that such molds are not used for this purpose, nor is it likely they will be. If for no other reason, they are very expensive (checked price on a fused quart dish lately?), and can't withstand the mechanical abuse they would experience in a gold pouring facility. Worst of all, they don't offer anything that can't be accomplished by other means, at far lower cost. Sort of reminds me of gold plating the bumper of a car when chrome would serve equally as well. 

The links you provided are interesting, and should prove to be useful for others. For that, thanks. 

Harold


----------



## T3sl4

Ease up, Harold. Ignorance isn't to be punished. It's a treatable thing. Just because an idea, at face value, is trivially unworkable, doesn't mean it can't be a starting point to something that is. The obvious step is replacing a metal that doesn't work (like cast iron) with one that might (like tungsten), though I wonder if fused quartz sticks to it (which would be another problem entirely!).

OP: realistically, you're unlikely to do anything with quartz, even bend tubing, let alone make your own shapes. Work requires an oxyfuel flame, usually hydrogen or methane, though acetylene works in a pinch I believe. Something that hot cools down very quickly, and even with a high pressure injector, you may not get a ball of quartz into your mold fast enough to fill it out.

Sintering is interesting, especially with sintering aids, like flux, cement, clay, etc. The downside is, quartz remains quartz, so you still get quartz shock at 573C. Since silica is a big component of pottery, this is one of the limits on the firing rate of common ceramics.

The best, easiest to make materials are mullite (a mixture of alumina and silica) and cordierite (magnesia, alumina and silica, with a somewhat lower melting point and much lower CTE).

Materials that haven't been mentioned yet are pyrolytic and glassy carbon. Commercial graphite is porous; these may perform better, especially with an inert or vacuum atmosphere.

Tim


----------



## MargueriteMingorance

People seem to have gotten confused about the process, here.

1) get a custom made tungsten mold, or use ceramic or something else (a number of possibilities were listed in the links above). Ceramic is cheap, you can buy the stuff for $20. A custom tungsten mold is a bigger investment. Judging by the prices posted by some of the companies that make them, expect to spend $150-500 for it.

2) use the mold to form fused silica molds for ingots. This way, you can make your own reusable molds, if you have a furnace that is hot enough to work glass. 1300C seems to be sufficient, if you give the viscous glass enough time to slump into the mold. Glass isn't a solid, it is amorphous. At room temperature it is just _very stiff_. Of course, you're not going to do this sort of thing with a torch, you need an actual furnace with a thermostat, you need some actual control.

3) Use the glass molds to make your gold ingots. This way, you can make your _own_ fused silica molds _cheaply_, so when they wear out, you can just recast them. Sand is cheap, just heat it up high enough.

4) When making an ingot that is exactly one ounce, you use powered gold, and measure it out into your fused silica mold. You put the whole thing back in your furnace, heat it up to 1100C (melting temp for gold) and let the gold melt. When the gold has melted, take it out, and use a torch to keep the top smooth until it cools.

BTW, one of the properties of fused quartz is it is very resistant to thermal shock, because it has a very low coefficient of thermal expansion. But even if your mold cracks, just make another one.

There is no need to pay someone else ridiculous prices to make fused silica molds, the process isn't that hard. If you wanted to do something like extrude tubing, there you would need some more specialized equipment.

This way, you can make ingots of an exact weight, every time. It solves the pouring problem, because you don't pour. You let the gold melt within your fused silica mold, which has a melting temp of 1700C (more or less, since glass doesn't exactly melt, it becomes less and less viscous, but at 1700C you can pour it). Make sure your silica is pure. If you get any alkali impurities in it, it lowers the viscosity. When you go to melt your gold, your mold might puddle.

BTW, with an inert atmosphere in your furnace (like helium) you can use graphite molds. They won't burn without oxygen.


----------



## MargueriteMingorance

Interesting article from the DOE's Office of Scientific and Technical Information.

http://www.osti.gov/bridge/servlets/purl/932641-trnH1t/932641.pdf

They were experimenting with fused silica molds to cast stainless steel parts. They like it, because with the low CTE, the mold doesn't expand much as it heats, so the parts produced are more accurate.

Here is a doctoral thesis on the crystallization of fused silica during sintering:

http://deepblue.lib.umich.edu/bitstream/2027.42/61652/1/baecj_1.pdf

The goal of the paper was to use sintered fused silica molds to cast parts for jet engines at temperatures as high as 1600C.




> Fused silica is the best candidate for non-reactive alloys
> fulfilling the restrictions on refractory ceramics used for investment casting such that it
> has thermal stability at high temperature resulting from a low thermal expansion
> coefficient (about 0.6x10-6/oC) and excellent thermal shock resistance. In addition, a
> fused silica core is easily removed due to the complete chemical leachability in aqueous
> solutions such as NaOH and KOH, where the solutions are non-deleterious to the nickelbase
> superalloys.



BTW, sintering is technically interesting, because it naturally makes very smooth surfaces. It is one of its inherent characteristics. Sintering works by reducing the sintered material to a lower energy state--one with less surface area. A smooth surface has less surface area than a rough one, sintering naturally smooths things out.



For extra credit, how do you sinter a _perfect_ sphere?


----------



## qst42know

I would guess producing fused quartz is out of reach for most. Unless you have a high pressure high vacuum electric furnace in your garage. However it's not out of reach for the General Electric corp.

The second page of this article has a good though brief summary of the process of producing fused quartz.

http://www.time.com/time/magazine/article/0,9171,718367-1,00.html

And don't forget the required annealing process.

http://online.momentivequartz.com/en/pdfs/annealing.pdf


----------



## Lou

I may wager I'm the only person here who has worked or even melted things in quartz.

Quartz is amazing stuff. It's not as expensive as everyone seems to think it is. I have a few things out of it.
Quartz molds and boats are available out of the catalog.

Oxymethane is unsuitable for all but the smallest things. Oxyacetylene works better and better yet is oxyhydrogen.

Of all the posts, Steve's seems the most knowledgeable--it's very easy to contaminate, and the salts from your fingers quickly aid in devitrification (whitening).
This is more of a cosmetic issue. Anyway, it is a great mold material. I've melted plenty of material in it and run reactions in quartz ampoules. 
Quartz is formed around graphite tools and dies--graphite is noncontaminating as it will simply burn off.

To everyone here: forget about working it. There are only a small number of people who can make apparatus of it. I've only ever made ampoules and graded fittings and a few metal--glass seals.
It's very hard, hot, and dangerous to work.


----------



## dtectr

sound like some ""prospectors"" we've dealt with here? (real prospectors will get what the "double" quotes mean)


----------



## Harold_V

It's pretty simple. "Clever" people will have no part of having their opinion taken from them. 

Had MargueriteMingorance spent any time in the trenches, facing the real problems that he appears to think he can address, he/she might see these issues from a different light. 

When one melts gold powder, the beginning weight and the ending weight is generally not the same. 

Why?

Because the best washed gold powder still contains traces of something that isn't gold, and it tends to be reactive when heated. It is common for miniscule balls of gold to fly from a lot of gold powder being melted. It may be small, but small is all it takes. 

I'm having a hard time understanding how an individual that appears to have no experience in the field of casting gold appears to have so many opinions, none of which are commonly accepted by those of us that have, indeed, cast gold. 

Note the variations here---none of which were desired. I did my level best to pour 10 ounce ingots. Two different times, in fact. Only by chance did I succeed, and only once in ten tries. 

Harold


----------



## MargueriteMingorance

Here's a technical guide to making stuff out of fused silica:

http://handle.dtic.mil/100.2/AD766494

Basically, a fine slip is made of the milled silica (a claylike substance, in other words), which is molded however you want. This is allowed to harden, then is dried at around 200F to get all the water out. It is then sintered for 2-3 hours at 2100-2300F. Presto, you have a fused silica item.

You can get used kiln equipment on ebay for a few hundred dollars that will do the job. Finding silica slip is much harder, strangely. Even finding powdered silicon dioxide, or something similar, is difficult. I found chemical supply companies that charge $40/lb for it. Here is a place that sells pottery supplies, that sells a "silica 325 mesh", which I suspect is pretty pure silica powder. At $4.25 for a 5 lb bag (plus shipping) It is cheap enough to experiment with. Or, you could go with the 50 lb bag for $15 (more shipping).

http://store.clayscapespottery.com/products/silica-325-mesh-sil-co-sil

It's pretty sad, that I can find a lot of manufacturers in China that sell pure silica powder for $100 a ton. In the US, I find cosmetic companies and dietary supplements (!). It is a worrisome indication of the state of american industry.


BTW, last time I checked, Marguerite was a _girl's_ name.

Hmm, yep, still no balls here. Whew.


----------



## MargueriteMingorance

Well, I'll edit out the insulting stuff, we don't need to see that again.



Harold_V said:


> When one melts gold powder, the beginning weight and the ending weight is generally not the same.
> 
> Why?
> 
> Because the best washed gold powder still contains traces of something that isn't gold, and it tends to be reactive when heated. It is common for miniscule balls of gold to fly from a lot of gold powder being melted. It may be small, but small is all it takes.



What if you melted it, then atomized it with very pure water? Would you then be able to melt it again without that problem?


----------



## qst42know

This is more of a mental exercise than anything else.

If you did produce this silica mold it wouldn't cool in a fashion that would produce a desirable ingot.

Cooling from the top down the shrinkage of the ingot would suck such a cavernous pipe it would not be very attractive anyway wouldn't it?


----------



## HAuCl4

MargueriteMingorance said:


> Here's a technical guide to making stuff out of fused silica:
> 
> http://handle.dtic.mil/100.2/AD766494
> 
> Basically, a fine slip is made of the milled silica (a claylike substance, in other words), which is molded however you want. This is allowed to harden, then is dried at around 200F to get all the water out. It is then sintered for 2-3 hours at 2100-2300F. Presto, you have a fused silica item.
> 
> You can get used kiln equipment on ebay for a few hundred dollars that will do the job. Finding silica slip is much harder, strangely. Even finding powdered silicon dioxide, or something similar, is difficult. I found chemical supply companies that charge $40/lb for it. Here is a place that sells pottery supplies, that sells a "silica 325 mesh", which I suspect is pretty pure silica powder. At $4.25 for a 5 lb bag (plus shipping) It is cheap enough to experiment with. Or, you could go with the 50 lb bag for $15 (more shipping).
> 
> http://store.clayscapespottery.com/products/silica-325-mesh-sil-co-sil
> 
> It's pretty sad, that I can find a lot of manufacturers in China that sell pure silica powder for $100 a ton. In the US, I find cosmetic companies and dietary supplements (!). It is a worrisome indication of the state of american industry.
> 
> 
> BTW, last time I checked, Marguerite was a _girl's_ name.
> 
> Hmm, yep, still no balls here. Whew.



How about picking some sand at the beach and milling it to size?. Or not milling it at all?.

Nice guide. Thanks!.


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## T3sl4

Possibly, a combination of silica fume and fine ground flint (flint is a form of silica which is commonly available very fine, e.g. 325 mesh) would do it. If it's still not sticky enough, you might experiment with bentonite (up to 5%), or perhaps fly ash (which may have a cementing effect and harden on its own).

Technical ceramics are typically made by pressing a powder with an organic binder.

Tim


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## MargueriteMingorance

HAuCl4 said:


> How about picking some sand at the beach and milling it to size?. Or not milling it at all?.
> 
> Nice guide. Thanks!.




Beach sand, if it comes from a reef, is calcium carbonate, CaCO3. Otherwise, sand is weathered minerals with all sorts of different chemical compositions. You can even have silver chloride sand :shock:


Wish this forum software could do sub and superscripts.


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## HAuCl4

MargueriteMingorance said:


> HAuCl4 said:
> 
> 
> 
> How about picking some sand at the beach and milling it to size?. Or not milling it at all?.
> 
> Nice guide. Thanks!.
> 
> 
> 
> 
> 
> Beach sand, if it comes from a reef, is calcium carbonate, CaCO3. Otherwise, sand is weathered minerals with all sorts of different chemical compositions. You can even have silver chloride sand :shock:
> 
> 
> Wish this forum software could do sub and superscripts.
Click to expand...


My beach is cooler!. 8)


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## qst42know

You may as well let your gold set up in a fused silica melting dish or in jewelers investment plaster. 

Those that cast the big bars that end up in bank vaults don't go to the trouble you are proposing. 

In the end what's to gain?


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## HAuCl4

Considering how soft and malleable gold is, really you can pour a button or a long ingot (like the jewellers use to make wire afterwards. Then cut it with a bolt cutter and scissors to the exact weight you want, then hammer it into any shape you want inside a steel mold or whatever. It'll fit perfectly, with perfect finish and you can get the weight as exact as you want if you have a good balance. If you have a hydraulic press you can even stamp it!.

It really, really rolls like butter!. 8)


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## goldsilverpro

Of all the recent threads, this one has got to be the most aggravating to me. No offense, but there has been nothing on here, at least recently, that has any practical merit at all. It's just a bunch of egghead, pie-in-the-sky thinking written by some egghead, pie-in-the-sky people. I realize that some people get into this sort of thing but I'm not one of them. I'm not saying you have to stop. It's just that I have to click to go on here for 1 second just to get rid of that damned orange flag. Reading the posts is a total waste of time.

The original question was: Can you pour exactly 1 tr.oz. at a time. No.

How can you make exactly 1 tr.oz bars? Cast bar. Roll it out to an exact thickness. Stamp out the blank. Coin the blank.

Case closed.


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## Harold_V

HAuCl4 said:


> Considering how soft and malleable gold is, really you can pour a button or a long ingot (like the jewellers use to make wire afterwards. Then cut it with a bolt cutter and scissors to the exact weight you want, then hammer it into any shape you want inside a steel mold or whatever. It'll fit perfectly, with perfect finish and you can get the weight as exact as you want if you have a good balance. If you have a hydraulic press you can even stamp it!.


That, of course, is exactly what has been said earlier, where one die strikes to achieve the desired results. 

Save your breath. That point has been discussed, all to no avail. We have an individual (that obviously has no clue) that is hell bent on re-inventing the wheel and will have no part of reason-----he simply must have a new wheel, even if it isn't round. 

I really like Chris' comments. That's exactly how I feel about this subject. I'm tired of trying to reason with a person that insists on having the last word--no matter how misguided it may be. I'm finished with this topic, and so is everyone else. It serves no purpose other than to expose how misinformed a person can be. The thread is now locked, and if a new one gets started that continues this subject in the fashion it has gone, it will be deleted. 

Harold


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