# making jewelry bronze alloy



## bmgold (Dec 13, 2008)

I'm getting a small sand casting kit to learn the sand casting process for making rings, trinkets and some castings for building model steam engines or maybe even a hit and miss engine or other small "toys". 

I'd like to try making my own jewelry bronze to practice with instead of buying it. I see it is 87.5% copper and 12.5% zinc. Is it possible to use copper pipe or wire and zinc from dry cell batteries to make my own alloy? I don't intend to sell this stuff so if it isn't perfect that is ok but it would be nice to get and alloy with a golden color to practice with. 

I know someone on this forum has tried or done this sort of thing before. There must be a jeweler (hobby or pro) on this forum. Any words of wisdom would be appreciated, if not I'll just try it when the kit arrives and see for myself.


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## qst42know (Dec 13, 2008)

You might try scrap red brass (bronze?) water valves. The ones that are sand cast should work well to re-cast and the alloying is already done.


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## bmgold (Dec 13, 2008)

Thanks for the idea on the water valves. I'll look around for some junk ones to try melting down for practice material. I tried a real quick test without weighing anything out and found that copper is a lot harder to melt into a button with the tiny tip I have on my torch right now. I was able to get a small piece and polished it up a bit to check the color out. It was close to the color I was looking for but a little light. Lighter than brass or copper but not quite right yet. I expect this is the material that would turn your finger green if worn as a ring but it sure would be cheaper than gold or silver to learn the process and might make something worth keeping as costume jewelry if it kind of looked like gold. If I stick with this hobby I'd probably eventually switch to lost wax casting for the jewelry but the sand casting is something I've wanted to perfect for some time now but just now thinking of casting precious metals. I've only tried aluminum and zinc alloys in the past and never quite got it figured out. The small kit should make it easier to practice since the amounts of both sand and metal would be much less and a torch should work instead of waiting 1/2 hour or more for the metal to melt and then more time for the casting to cool down enough to dump out only to find out there was something wrong. By that time I never wanted to remake the mold and remelt the metal to try again. I've got many plans for the day I do figure it out and also have more time to do stuff like that.


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## bmgold (Dec 14, 2008)

This making my own alloys idea may be harder than I thought (like most things I try). Here's a couple pictures of my attempts at it. The first one was just mixing stuff without weighing anything out. The little "gold" coins were bought on E-bay for $2 each but I don't know what they are. Probably just gold plated. They look nice for such small coins and I didn't spend much on them but they are not pure gold. They weigh exactly 1/2 gram each. The ring is 18K to try to show the right color. The other lump of metal is my first attempt after a bit of polishing. It was black at first (probably oxidized the copper or the zinc) It's hard to tell from the picture but it has a very slight yellow tint to it. Not quite copper, not quite brass and not close enough to gold color to suit me. It might work for practice but not good enough to call jeweler's bronze.

The second picture shows my next attempt before cleaning the flux off of it. I weighed out 6.44 grams of copper house wire that I had already cut and calculated I would need 0.94 grams of zinc which I weighed out pretty close from a dry cell battery inner case. I melted the copper first in a cupel (It's all I had) that I coated with borax. It took some time to get it to melt into a puddle even with a larger torch tip. Then I dropped in the piece of zinc which instantly vaporized.  I expect what I ended up with is mostly copper. I'll polish it up a bit when I go back to work Monday but I think I'll give up on yet another idea. Still might try the water valve idea when I find a scrap one. Might also try just melting a bit of brazing rod to get enough metal for a small ring or something. Probably not real cheap but I have some here already and could sacrifice one for educational purposes.

The casting kit should be here Monday or Tuesday and it comes with a little practice shot and I ordered an ounce of sterling shot which cost as much as a one ounce .999 silver round at the coin shop but I figured I'd try the shot sometime when I figure the process out. I'll try to post a picture of the kit when it arrives unless someone objects to all the pictures. (i got the camera set to the lowest quality setting to keep the size down).


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## qst42know (Dec 14, 2008)

Zinc vapors can cause permanent damage to your lungs. Please be careful. 

If you know what zinc vapors smell like you are likely breathing in too much.

This is cut from the wiki.

"Safety
As a food additive, Zinc oxide is on FDA's Generally recognized as safe, or GRAS, substances[13].
Zinc oxide itself is non-toxic, however it is hazardous to breathe zinc oxide fumes. Fumes of zinc oxide are generated when zinc or zinc alloys are melted and oxidized at high temperature. This occurs while melting brass, because the melting point of brass is close to the boiling point of zinc.[14] Exposure to zinc oxide in the air, which also occurs while welding galvanized (zinc plated) steel, can result in a nervous malady called metal fume fever.[15] For this reason, typically galvanized steel is not welded, or the zinc is removed first.[citation needed]"


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## qst42know (Dec 14, 2008)

I haven't had any dealings with this company but their products seem just what you are looking for. By the pound and in shot form. It looks like you can get a pound of casting grain for about the cost of the coins you bought.

http://www.contenti.com/products/metals/166-663.html


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## bmgold (Dec 14, 2008)

Thanks for the link and the zinc information. I'll keep them in mind and compare prices and shipping charges when I get the kit and get a chance to try it out. I noticed the cheapest one has a little lead in it so I doubt it would be the best choice for rings. It looks like they have a lot of tools and supplies so I'll have to check out their site when I have more time and a little money to spend.


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## bmgold (Dec 16, 2008)

I got the sand casting kit from http://www.freshmans.com/ (Thanks Harold for the indirect recommendation of this company... http://goldrefiningforum.com/phpBB3/viewtopic.php?t=3787&highlight= ...They have very good e-mail support) and although I haven't had a chance to try it out yet it looks good. The size is 3"x4-3/4"x2" so it is made for jewelry, emblems and other small stuff. The sand is not water based and looks like it will make pretty good impressions. It came with a couple ounces of manganese bronze casting metal and I got an ounce of sterling silver shot. The shot was from freshmans and the bronze was included in the kit. The bronze is not nice round shot but just rough and sharp pieces (should work just fine though). I'll probably try lead as a first casting metal just because I have it and it melts easy with a propane torch. Then I don't know what I'll try next using the included crucible since I only have the one for now and it can (or should) only be used for one type of metal.


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## bmgold (Dec 19, 2008)

It looks like, from my internet searching, that what I was attempting was to make brass and not bronze. Bronze is copper and tin and not zinc. I'll have to try it again using some tin solder instead of the zinc. Actually, I see that the actual yellow casting shot is not as expensive as I thought so I'll probably just order some and be done with it but I would still like to be able to make my own from scrap wire and tin. The only source of tin I have is the lead free solder and that isn't real cheap. Anyone know of other sources for tin scrap?

Update: I ordered some yellow casting metal from freshmans.com. The cost, I think, was $0.82 for a 4 ounce pack if bought in quantity. I ordered 20# so that should be enough to last me a long time unless I cast larger things than rings or other small trinkets with it.


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## butcher (Dec 19, 2008)

I get zink in a large roll for roofs, kinda like a roll of flashing, moss strip to prevent moss on roofs at a local hardware store, its pure zink fairly cheap, supply one hardware, ILL try and find brand name for you, the same company sells zink sulfate moss remover I find that in the garden center to remove moss from sidewalks.

tin solder, 95% tin 5% antimony. look for lead free solder read roll tag or look up MSDS

I  editted mistaken identity


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## bmgold (Dec 21, 2008)

My first attempt at a sand mold failed. The mold turned out ok but I underestimated the amount of metal (lead) it would take and it only half filled the mold. I'll give it another shot when I get warmed up. It's cold in the shop. I don't really think a ring will turn out very good without removing a lot of metal to get the inside diameter right and get the whole thing smooth and polished. Not a big deal with the yellow casting metal but with gold or even silver I don't know. I guess I could save all the turnings and fillings and that would give me some practice at the gold refining but I think the lost wax process would be a better choice. The sand is pretty fine and it might be possible to get a pretty good finish needing little metal removal but I don't know yet.

My experiments with the homemade bronze or brass are getting better. I got a yellow, brass looking lump of metal from the last try. I'm waiting to see if it turns red once it oxidizes a bit. I'm running out of acetylene so I'll be putting the experiments on hold once the tank is completely empty but will keep playing until then when I get time. The copper seems to take a lot of heat to melt and forms a layer of dark oxide on it's surface but it may work better when I use the actual crucible that came with the kit. A brazing rod looks just as good and doesn't require any homemade mixing of metals and a pipe fitting also looks like it would work. For any more than possibly an ounce of metal at a time I would need either a bigger tip, or a larger crucible and a furnace to melt. I have an electric furnace without a temperature controller and also a homemade charcoal foundry furnace that should work but I'll stick to small quantities at least until I learn the process and prove I can get good results.

My order of the yellow casting shot is scheduled to ship on Monday but I don't expect it to be delivered before Christmas. I think that will be what I use the actual crucible for since I'll have plenty to play with. The color of the "fake gold" is pretty close to right but the weight is wrong. Should work good for practicing though and could make some nice looking items whatever they turn into.

edited: Added a picture of a second attempt at a sand casting. This was molded from a washer (ring?). There was no draft on the pattern and the mold was damaged when removing the washer but I intended, and did, pour it with lead so it was just a test anyway. At least it filled the mold without having any riser. There is lots of flash both inside and outside but I knew it would since the mold was rough. This will just be remelted anyway and was just done to prove that the mold would fill, which it did. If I only posted results when things worked perfectly I would never post anything but questions :lol:

I watched an online video on lost wax spin casting and I have to give up on that dream. I waste a lot of money on equipment for this hobby but there is a limit


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## Harold_V (Dec 22, 2008)

If you do not understand the difference between an oxidizing flame and a reducing flame, you need to study a bit. Copper will melt without forming heavy oxide, but you can't do that with an oxidizing flame. 

There may be more to this than meets the eye. Pure copper is not easy to work with------a little zinc makes a big difference, being sacrificial. Everything is a balancing act when you're working with molten metals. 

Harold


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## bmgold (Dec 22, 2008)

Thanks Harold. I probably had a slightly oxidizing flame to get enough heat to melt the copper. I guess I need to switch to an even larger tip. I was only melting 1/2 ounce or so but it took a while to make the copper melt and flow. I checked the bead/lump I made yesterday and it turned slightly red so I didn't get the brass or bronze made right yet. Boy polished copper looks nice, at least for a short time. Actually, it still looks nice but not like gold. It's still real shiny just turned red. Some of the dark color washed off with hot soapy water so it might have been dirty flux but it could have been oxidized copper or zinc or tin. I'll quit playing with this once I get my order of the yellow casting shot from Freshmans. Thanks for the link to that company. They seem like real nice people and they send e-mail confirmations of orders and when I called them on the phone they remembered me from my orders and e-mails. I always prefer to deal with small, friendly companies and their prices don't seem bad either.


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## bmgold (Dec 26, 2008)

To get away from this homemade bronze idea, what about making my own sterling silver? Would I likely have the same problems? Let's assume I would weigh out the silver and copper and be sure to use a reducing flame and a proper crucible and not just guess at amounts like I have with the bronze attempts. Would I need to turn the pure silver and the copper into shot first or could I just melt the proper amounts of each together and maybe mix them with a clean carbon rod or using the torch flame to stir the liquid metals?


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## Harold_V (Dec 26, 2008)

Making your own alloys isn't a big issue. How you go about melting can be. One of my customers was big on making CTR rings (that stands for Choose The Right, a slogan that the Mormon Church has for members. The rings were made for them under license). I dispensed my silver directly from the parting cell in the form it created, i.e., silver crystals. He cast rings in a large cylinder, from a motorized centrifuge, roughly 50 at a time. He weighed out the amount of silver need, along with the proper amount of copper wire (copper made into wire is pure, of necessity), and torch melted. A quick stir with a carbon rod and the rings were cast immediately. 

There is no particular advantage in melting the material, then pouring to shot. If anything, it can be the wrong move. Each time you melt alloys that can oxidize (copper does, although it's difficult to oxidize silver), you form oxides that lead to problems. They manifest themselves in jewelry in the way of porosity in the castings, often so severe that they are too difficult to eliminate. The alloy, at that point, should be refined. 

You will come to realize that the presence of copper in silver prevents silver from absorbing as much oxygen, so a sterling alloy will be somewhat more forgiving of the spitting and crabbing for which pure silver is known. The only problem then is the degradation of the alloy by improper, or excessive melting. 

If your work lends itself to being melted only one time, then cast, that's the best possible avenue for you to pursue unless you have the luxury of working either in a vacuum or an inert atmosphere. The typical home application rarely has those capabilities. None of my customers did. 

edit: I should note that if you make alloy from cement silver, you are subject to questionable results. Traces of undesirable elements have the ability to hitch a ride with cement silver, which is almost never pure. I strongly suggest that if you intend to alloy your silver to sterling that it be parted electrolytically first. 

Harold


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## Lou (Dec 26, 2008)

The issue with most alloys made by the amateur is improper stirring, improper temperature control, and improper atmosphere control. In addition, it helps if you have a good balance to weigh out your constituent elements.

Bad stirring means your alloy will be heterogeneous and prone to stratification on cooling (which would mean it would be worthless to assay a piece of such a bar). Improper temperature control can either volatilize away some of your metals, or, without a controlled atmosphere, lead to excessive oxidation or gas absorption.

If I feel like it, I can melt silver all day long without worry of oxygen pickup and cast it under inert gas or in a vacuum. However, there are limitations to doing this, and like Harold implied, it's not cheap and it's usually not easy to setup such a system. In most crucible furnaces and direct melting setups that use a gas flame, using a vacuum or inert gas is out of the question. This is where induction and resistance heating come into their stride.

I would never torch melt an alloy, especially a brass or bronze that has zinc or lead which can volatilize. Torch melting pure silver, pure gold, pure platinum, and pure palladium is fine (palladium is pushing it, but use a slight reducing flame) and there's little worry about it. Don't melt any alloy more than you must--each time you melt an alloy you increase contamination and will decrease the attainable quality of any casting.


As for melting under a vacuum or in inert atmosphere, one can set himself up to do that with good success for under a thousand dollars. You will be limited in quantity. If people want to know how to do it, ask me and I will describe it in great detail.

Lou


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## allanwcoty (Dec 26, 2008)

Lou, what kind of quantities are you talking? I'm not doing any melting yet but would like to hear about your idea's. Have a Happy New Year everyone. allan


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## Platdigger (Dec 26, 2008)

OK Lou, we're askin........
Randy


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## bmgold (Dec 27, 2008)

My idea to make my own sterling was to use a silver round that is already .999 fine and the copper house wire weighed out as close as I could to get the right proportions for sterling. Since I have no way to test the sterling and couldn't stamp it as sterling anyway, I would have to go by weight and hope it was right. I'm not a jeweler and don't intend to sell my creations so the exact mix might not be real critical anyway. Is sterling really that much harder than pure silver or is it used more to lower the cost than to increase the strength and durability? Would just using pure silver be a better choice for someone just trying to learn the casting and making of jewelery? I can get pure silver rounds for the same or less cost per ounce as the sterling shot so unless I made my own sterling, the cost to use pure silver wouldn't be any higher and might be cheaper especially counting shipping costs. 

As far as the detailed description of vacuum melting or whatever goes, I and it seems others are interested so if you have time to write it up then go for it. The more knowledge we have the better even if I can't spend the $1000 to set it up, it would be nice to know how it would be done. 

Thanks for everyones help and thanks for keeping this great forum active and very educational.


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## Harold_V (Dec 27, 2008)

It's easier to work with sterling than pure silver, if for no other reason, the problems associated with silver absorbing oxygen. The negative is you can't melt it indefinitely, but that's not an issue if you have refining capabilities. You also have to be somewhat more careful to not over heat the alloy, which accelerates oxidization. 

There's nothing preventing you from alloying to any condition you desire--even coin. The only real concern is if you market your goods. You should mark them according to your alloying, for the sake of honesty. 

Alloying even under coin isn't a big deal. You won't give up much in the way of whiteness------I processed some silver flatware from one of the Scandinavian countries that was down around 70% and it was still surprisingly white.

You might also consider buying sterling "coins" or ingots. You might find the price better than having shot shipped. It's easy to melt such an item, certainly no harder than shot. You might even get a decent price on some that have been defaced. Makes no difference if you're going to melt them. 

You can even alloy up if you have coin and want sterling. Use your imagination and check at the local coin store, looking for junk silver. 

Harold

edit: corrected typos. No change in content otherwise.


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## bmgold (Dec 27, 2008)

Thanks Harold,

I thought about the absorbing oxygen and the sprouting of silver after I made the post but didn't have a chance to change it so I left it as it was and expected someone would mention that fact. As far as your other comments about alloying up or down, thanks again. I forgot about coin silver being 90% I think. Some might be even lower and they still look good. I could stamp or engrave anything I made as to it's purity but it would just be my word and not a certified value. Probably not an issue at least until I would get good enough to sell the stuff I would make.


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## Lou (Dec 28, 2008)

Melting something in a vacuum and casting something in a vacuum are two entirely different things, one is easily accomplished, the other, not so much.

If you want to cast things under vacuum and do it right, you'll need induction, a vacuum pump, and a vacuum chamber. Unless you build the induction furnace and vacuum chamber, this will be expensive. 


Often times there are alloys that I need to prepare, most of which are air or moisture sensitive. What I do for melting them can also be done for melting most any other material that fuses below about 1500C/2730F. You're only limited in size by how big you make your apparatus, and also by how much output your torch has. To do this, I take a quartz tube, of whichever diameter, and place my pre-massed materials inside the tube (if they're reactive, this is conveniently done in a dry box, but there are other ways to get it in there). This quartz tube can be as long as you wish, but for under 50g of material, keep it about 18 inches long (45 cm).

At one end of this tube, you can either hook it up directly to a vacuum, or preferably, you can hook it up to bi-valve that allows for you to pull a vacuum, and the back flush with an inert gas like argon.*

Once you have the metal pieces or powder in the tube, start the pump and pump down the tube. If you have a bad vacuum pump or are using a water aspirator, to remove all oxygen and nitrogen from the system you can use Schlenk technique. The idea here is that you pump down the tube, seal it from the vacuum at the valve, and then introduce the argon into the melting tube. Then you pull a vacuum again, then you introduce argon. Do that several times and nigh all of the non-inert gases are removed. Now you can either melt under vacuum (preferable because it degases your melt), or close the vacuum and melt under the residual inert atmosphere. Take the torch to the quartz tubing and the metal will melt quickly. It will not stick to the quartz unless it has gallium or indium in the alloy. 

If you want to keep the sample inviolate, then you had best heat above the now cooled mass with the torch until it is incandescent. This will be at nearly 1750C and you must take suitable precaution to protect your eyes (cobalt glasses or welder's helmet) from the UV output. If you do pull a vacuum, make sure you go easy on the torch keeping the quartz from melting because you will get holes in the wall from the pressure differential. While still maintaining heat from the torch, pull slowly down on the cool end of the ampoule-to-be and it will seal shut. This all takes no longer than 10 minutes to setup, and a minute or so to do.



*Thinking out loud here: I can see how I could possibly rig this up for someone with adequate glassworking skills and sufficient bravado to modify the apparatus and make it so one could melt under vacuum and cast with argon as the push gas. I don't think I could easily describe the system though, but I will try to draw it out in Paint if anyone wants to see it. It would not be a true vacuum cast, since the melt would be exposed to air for a few tenths of a second.


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## goldsilverpro (Dec 28, 2008)

If you look around the internet for jewelry making supplies, you'll find proprietary casting alloys for adding to silver to make sterling. They are mainly copper with small amounts of other materials. Some contain proprietary additives which act as oxygen scavengers, which reduce the amount of copper oxides when casting. Also, some contain tarnish inhibitors.


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## Lou (Dec 28, 2008)

Proprietary additives?

Ahem, can you say copper phosphide  ?

I use that for deOxing copper and it works a treat.
Supposedly trace amounts of cadmium helps improve casting quality and additions of selenium greatly improve silver's resistance to tarnish. I forget where I read that, if anyone has details, let me know.

I've also seen copper slugs that are lithium filled, those are used for removing oxygen from melts.


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## qst42know (Dec 28, 2008)

For the ultimate in tarnish free sterling some are adding Platinum. There are no rules for what the 7.5% must be. The wiki lists a few.

http://en.wikipedia.org/wiki/Sterling_silver


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## goldsilverpro (Dec 28, 2008)

There seem to be several things that work. I remember seeing germanium and silicon mentioned, but they may have been tarnish inhibitors. I saw a patent that listed a bunch of things.

"Proprietary" is what the manufacturers call these additives. If they can maintain an air of mystery and maintain a doubt of what and how much is in the mix, that is usually enough to keep many buyers from making their own. They don't want to screw things up. The proprietary mix works.

The plating industry uses a plethora of "proprietary" chemicals. The primary brightener in a bright nickel bath is usually a solution of sodium saccharine (very, very inexpensive). Platers use a lot of this and I would imagine it now runs about $40/gallon. Most everyone thinks it is PROBABLY saccharine of some unknown concentration but, who knows, there might also be some additional stuff in there??? It's not worth a $20,000 nickel bath to save a few $100.


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## bmgold (Dec 28, 2008)

Wow! A lot of information on this post now. I'll be burning up some space in my notebook. I have to check out the wikipedia site on the sterling info. I didn't realize that sterling could contain anything but silver and copper. Could make refining a little more tricky depending on what else is in there. 

I gave the homemade brass another shot. This time I was a little more patient and made sure not to use an oxidizing flame and also used a little soda ash and borax and stirred the molten metals with a piece of wood and also with a piece of wire as it was melting. There was little if any oxidation this time. I took a picture of the polished bead but there is no sense posting it since my other tries looked good right after polishing too. The test will be if it stays yellow or turns red after a day or so like the other tries did. The brazing rod lumps still look good and the melted brass pipe fitting is still a nice golden yellow color. The real yellow casting metal that came with the sand casting kit also stayed the same color. My 20# order of the practice casting shot should be here soon. I built a pattern for casting a simple ring but haven't gotten a good enough sand mold to try pouring it yet. I'm not sure 2 degree draft is enough but I probably just have to take my time and be careful when removing the pattern from the sand. 

Thanks for the advice and info. I hope I'm not the only one learning from this post.


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## Harold_V (Dec 29, 2008)

Add this to your notebook. 

It's not wise to stir molten metals with metallic objects. Molten metals are generally strong solvents of other metals, and contaminate the desired metals when so exposed. In some cases, you can destroy desirable properties, rendering all your efforts wasted. 

Use a carbon rod for stirring small lots of metal. 

Skim any flux you may use before trying to cast objects. It will generally pour off with the metal, ruining castings. 

Harold


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## bmgold (Dec 29, 2008)

Thanks Harold,

I stirred the mix with the copper wire that I was melting into the mixture. I also used a wooden rod to stir with since I don't have a carbon rod small enough and didn't want to use a dirty rod from a dry cell battery although that might work if it was scrubbed up. Any thoughts on that low budget carbon source? The wood instantly burst into flamea but seemed to work to stir with and my thoughts were that the charcoal produced would help keep the mixture from oxidizing. Something must have worked since the only thing on the bead was a little red stained flux. I didn't pour the metal but just let it solidify a bit and then grabbed it with tweezers and cooled it in water. 

By morning the bead still looks yellow with no hints of red copper color yet so maybe I got it this time. It was still just guessing on amounts of each metal so nothing was weighed. I didn't actually think it would work but was just playing. I still have more wire and a little zinc from the battery shell so these beads are small tests. Probably half to three quarter ounce each. To bad it wasn't real gold.


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## butcher (Dec 29, 2008)

http://www.lacywest.com/


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## Harold_V (Dec 30, 2008)

If you had good fortune with a piece of wood (stick) and have a good supply, there's nothing wrong with using the same thing. Otherwise, jewelry supply houses sell carbon rods intended for use in stirring metal that is melted for casting purposes. I have no idea of the cost, but they often came in with floor sweeps from my customers. Once I'd cleaned the end off, returning the values to the customer, I'd use the remains when I inquarted. I held the carbon with a pliers, so length wasn't critical as long as it was more than a couple inches long. 

I never, in all my years, had to buy any carbon rods. They came in at a speed that was adequate to keep me supplied, but not over-supplied. To me, it was one of the perfect examples of recycling. I won't mention the fact that I'm a cheap bastard!  

Harold


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## Lou (Dec 30, 2008)

I know that they were free Harold, but this is where I disagree--carbon is nice and non-contaminating but boy if it doesn't heat up right quick! I used to use carbon rods and pliers to grip them like you Harold--I would sand down square one end of the graphite to that the pliers gripped well and use that, but let me tell you how far superior a quartz stirring rod is! Holding them in pliers is just too awkward for me.

Gold, silver, copper and the like--they don't wet quartz. Heat conductance is hardly a problem. Thermal shock resistance is superb. Durability is very good. 


Here's a link to anyone looking for it:

http://www.technicalglass.com/rod.htm

I do business with that company, and have not been disappointed yet.

They also have numerous other cool things, including some quartz trays that would probably make darn good ingot molds if one wanted to use them that way.

Only thing I don't like about quartz is that you can't use it for Pt. Pt and quartz have about the same fusion point, and I am NOT enthusiastic about melting a bunch of very dense material in a container that is in a semi plastic state. Putting the nail in the coffin is the fact that quartz has a high vapor pressure at Pt's melting point, and if you aren't protected with a suitable mask, you will be sucking down SiO2, which can lead to silicosis. 

That last comment above is directed mostly towards Steve, because I recall him mentioning that he bought quartz crucibles for melting Pt. He should rather invest in alumina.

Lou


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## bmgold (Dec 30, 2008)

I got my order of yellow casting metal today and I was wrong about the quantity. I guess I read the web site wrong when I ordered it.  

I got 5 pounds and not the 20 pounds that I thought I was getting. It worked out to over $17 per pound counting the shipping charges. Not quite as good a deal as I originally thought but on a brighter note, it does look nice and 5# will still make a lot of rings. I won't be ordering any more though. 

My last homemade attempt at making brass (copper and zinc) still looks good with no signs of oxidizing back to the copper color so I think I finally got it.  The reducing flame and the stirring probably made all the difference. At the price I paid, maybe making my own would make sense if I did it on a larger scale in a foundry outside instead of with a torch and by the pound and not by the ounce. My last try looks pretty similar to the purchased stuff when they are both polished up a bit. Mine is a bit darker yellow than the other stuff but with some actual weighing and adjusting I am sure I could get any shade from yellow to red to silver depending on the amount of zinc. I haven't tried the tin again but may someday to try making bronze instead of brass. Considering the copper and zinc I used were scrap and free, my only costs for the ounce or so I've made so far is my time and some oxygen and acetylene, a little bit of borax and a cupel that I used in place of a real crucible. Now that I type it all up I guess I spent as much or more per ounce as the store bought stuff but the big expense (the cupel) was used for several tries and it should work a time or two more with care. Hey, education ain't free. Well, this forum has a lot of free education if you put the effort into studying.

I made some adjustments to my ring pattern. I drilled and tapped a couple tiny 0-80 holes on the back to give me something to hold on to to get it out of the sand mold. The ring will be a bit too thick but I figured for a first try I should make it big enough to work with easily and I intend to make it out of the yellow casting metal or something other than gold or silver (at least at first) so if I have to file, sand, polish or even machine some material off of it to make a usable ring from the casting I won't be risking loosing precious metals. With care, I guess I could use silver or gold and then save the chips and dust to refine back to pure metal but I'm not up to that point yet. I do have a few coffee filters containing some gold foils just waiting until I have enough volume to be worth moving on to the next step but I have so many projects started that I can't count them all let alone finish them. Someday...If I live long enough...
:lol: 

And to Lou :


> Gold, silver, copper and the like--they don't wet quartz. Heat conductance is hardly a problem. Thermal shock resistance is superb. Durability is very good.


 How would say a 1/4" (6 or7mm) x 4 foot long quartz rod handle stirring a few pounds of this brass/bronze in a clay crucible using a charcoal fired foundry? Is that too small of a diameter? What about that company's (http://www.technicalglass.com/rod.htm) shipping costs and shipping speed? Minimum order? I'm used to dealing (at work) with a couple companies that get your order to you within a day or so. No extra charge for this service either so I'm a bit spoiled and a couple weeks or more to get your order to you seems slow. I know, few companies are this fast. Just wondering how fast or slow this company might be.


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## Lou (Dec 30, 2008)

They are rapid for me. Granted I live an hour by car from them, but my experience is that they process your order either the same or next day depending on when you place the order, if it's before 4pm, usually same day order processing, and it's shipped either that day, or the next morning. If you order after 4pm, your order will mostly like go out the day after.

I receive my small orders the day after placing them 

There is no minimum order as far as I know.
I don't know about the shipping, I never cared, they just bill it to my account.

I really like them, or I wouldn't recommend them. They haven't done me wrong (yet).


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## goldsilverpro (Dec 30, 2008)

I think that carbon rods are used in arc lights.

The rods I used were about 3/8"-1/2" in dia and about 12", or more, long. Besides stirring, that were used to collect the molten slag off of the top of the metal in the crucible. This was done quickly. If not, the carbon got too hot and the slag dripped off and didn't stick. If the carbon is too cold, it will pick up metal. If done right, essentially all of the slag can removed, with no metal, before pouring the bar.


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## Harold_V (Dec 31, 2008)

Yep---what GSP said. You can also use air arc carbons that are used in welding. Only problem is they have a copper skin, but for skimming and stirring casting alloys, that wouldn't be a problem. 

Harold


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## bmgold (Dec 31, 2008)

Here's a couple pictures. The first is the 5# bag of yellow casting shot I just got and the second one is a comparison of my attempt on the left and the real stuff on the right. Both pieces were polished and they both look like the same color and shine. I think I finally did it.  



Thanks for all the comments and advice. I'll check on the air arc carbons the next trip to the welding shop.

update Jan 2, 2009: went to the welding shop but forgot to ask about the carbons  I checked freshmans.com and the stirring rods are there. 1/4" x 12" are only $2.55 and 1/2" x 12" are $3.75 The quartz rods are there also and are 3/8" x 12" for $22.85 (seems like a lot but maybe they last a long time?)

I checked http://www.mcmaster.com/ (McMaster-Carr web site) and the 1/4" x 12" Air Carbon-Gouging Electrodes are $3.66 for 10 of them so this may be the better place to get them. They are real quick at shipping orders and they have a lot of stuff.


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## Harold_V (Dec 31, 2008)

Lou said:


> I know that they were free Harold, but this is where I disagree--carbon is nice and non-contaminating but boy if it doesn't heat up right quick! I used to use carbon rods and pliers to grip them like you Harold--I would sand down square one end of the graphite to that the pliers gripped well and use that, but let me tell you how far superior a quartz stirring rod is! Holding them in pliers is just too awkward for me.


I don't have a problem with anyone not agreeing with what I did. Rarely do I consider my methods as being so important as to be the standard by which all others should perform. Could be I'm that way about my washing procedure, though! :wink: It took a long time for me to conclude what worked best, and I know it is _*very*_ good!

I had a wheel weight pliers that held the rod perfectly----and had an endless supply, so I wasn't concerned with any of the problems you mentioned. My use was reserved to stirring lots of inquarted metals, which took but an instant. Heating of the carbon was not a concern in the least, thanks to my having an asbestos melting tray, and not having to handle the carbon while hot. 

I never fluxed enough for that to be a problem, choosing, instead, to melt in my furnace when heavy flux was a requirement. I then poured to a cone mold for easy recovery of the values. 

I had one piece of quartz come in and used it as well. Considering my application, I could see no particular advantage to its use, and being thrifty (cheap) and having a desire to minimize waste materials, I found the recycling of carbon rods, many of which were several inches in length then I received them, was to my advantage. I could use them down to about two inches in length before they no longer served their purpose. 

Were I mixing alloys that were intended to be used, I would not have used recovered scrap carbon rods, to avoid contamination. 

Harold


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## bmgold (Jan 3, 2009)

I tried the sand casting again and the result is pictured on this message after some trimming of flash and a little sanding but then I realized it is only a lead ring and can't be worn anyway so stopped polishing and any more work on it. I was trying to make it out of the yellow casting shot but a propane torch just wouldn't melt it. The directions state propane is ok but I guess they mean propane and oxygen  

For anyone that missed my editing of a post a couple back I added some links to get the carbon rods CHEAP and without the copper coating. Here it is again.

I checked freshmans.com and the stirring rods are there. 1/4" x 12" are only $2.55 and 1/2" x 12" are $3.75 The quartz rods are there also and are 3/8" x 12" for $22.85 (seems like a lot but maybe they last a long time?) 

MUCH CHEAPER SOURCE
I checked http://www.mcmaster.com/ (McMaster-Carr web site) and the 1/4" x 12" Air Carbon-Gouging Electrodes are $3.66 for 10 of them so this may be the better place to get them. They are real quick at shipping orders and they have a lot of stuff.


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## bmgold (Jan 4, 2009)

Here's a close up shot of my next attempt at a sand cast ring. This time I used some zinc from a failed attempt at making bronze/brass alloy. This did melt with a propane torch.

You should be able to see the two small holes in the edge that were from my tapped holes to extract the mold from the sand. In the cast part they are not very deep but did form small pockets. Also as a note: I couldn't find any 0-80 screws locally and don't want to order a pack of 50 just to get 2 screws so I used a bent piece of mechanics wire to put in the holes to extract the mold from the sand. There is also a defect from where the metal entered the ring from the pouring sprue. The sand texture can also be seen both inside and outside on the ring.

All in all I'm getting pretty close to what I hoped for with this process. I need to spend a little more time practicing and be a bit more careful cutting the runner to the part but I like the results so far. Next step is to try some of the yellow casting shot I got to make an imitation gold colored ring.


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## qst42know (Jan 4, 2009)

Are you trying to save the sand mold for repeated castings?

The mold that leaves the image in the sand may need a means to extract it but the sand is meant to be broken from your cast part. No extraction holes should be necessary on the finished part.


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## bmgold (Jan 4, 2009)

> Are you trying to save the sand mold for repeated castings?
> 
> The mold that leaves the image in the sand may need a means to extract it but the sand is meant to be broken from your cast part. No extraction holes should be necessary on the finished part.



No, the sand mold is completely destroyed each use to get the part out. I do reuse the sand but I have to remake it each time. The holes in the finished parts are from the impression left in the cope half of the mold from the pattern. The pattern has holes in it to help extract it from the sand mold. I need to do some more work on my sand molding techniques and my attempts so far were done pretty quickly since I am still testing it out and didn't want to spend a large amount of time on the mold only to find out that it didn't fill completely or had other problems. Now that I see how good this new oil-bonded sand works I will spend some more time trying to get a cleaner and better mold to pour the metal into. I wish I had a better way of removing the pattern from the mold instead of using the holes but this was what I made as a pattern so far.

Maybe making the pattern different would help or maybe just doing a bit of adjusting and cleaning up the mold would help. It may be better to have small projections on the finished part instead of the indentions. The pattern for the ring that I made is a little small on the bore and is thicker than is comfortable as a ring but I wanted to make it big enough to easily work with and leave a little metal to file, sand or machine off to get a smooth finish to the finished part. Of course I am not working with gold or even silver (yet) so the material that needs to be removed will have little value and probably doesn't need to even be saved to try to refine and reuse.

I really like the new oil bonded sand that came with the kit. It seems to work much better than the homemade green sand (water bonded) that I tried years ago with aluminum castings. The sand texture still shows up in the finished parts so they will need some work to get a smooth, shiny finish but I didn't expect finished parts right out of the sand. I know that wax casting would make a much nicer ring or whatever but this sand casting kit was much cheaper than getting the tools and supplies needed to do the lost wax casting.

I'm still no competition to my local jewelers and don't intend to do this work to sell. The same as the little bit of gold refining I have and will do, I am just playing and learning. Now if I get good enough at it and someone wants to give me money for my work who am I to complain but that is not my intention. This is just a hobby for me at least for now. I suspect that once a hobby becomes a business it becomes less fun. Gold may be different but I doubt it.


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## butcher (Jan 4, 2009)

I havent ever tried that, but from what I can tell you are getting close to succcess, looking good and a neat project, maybe mike can give you some pointers, he made that big mikey mouse for disney. I suspect they dont come out of mold perfect and need machine work to finish them up.


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## Anonymous (Jan 4, 2009)

Lost wax will make better castings when making stuff that small. Also might try lost foam. I would go with the lost wax, read up its not has hard as it sounds.

Jim


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## Harold_V (Jan 5, 2009)

bmgold said:


> I suspect that once a hobby becomes a business it becomes less fun. Gold may be different but I doubt it.


Keep that thought. My refining was strictly hobby----one I enjoyed beyond belief. 

I allowed it to become a business. It was not my idea-----but I didn't discourage it---eager to get away from machining. Big mistake. It took many years, but I came to hate refining just as I had come to hate machining. A steady diet, 24/7/365 of _*anything*_ wears out its welcome. 

Harold


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## bmgold (Jan 5, 2009)

Harold,

I knew that comment would get a reply from you either rejecting or confirming my thought of hobby/business. I'm glad you don't hate refining so much you don't even want to talk/type about it. 

I work as a machinist and still love it but it is more the company than the work. I worked at other shops and hated even going there each day and counted the hours till quitting time. That's no way to work so I eventually left that company. I think I've found the place I want to be and may work there till I die or retire or the work runs out. Only 4 people counting the 2 owners who both work in the shop when they aren't in the office. 

Thanks for keeping this forum going with your knowledge and willingness to keep everyone in line with their feet on the ground.


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## bmgold (Jan 6, 2009)

I have tried my casting experiments a few more times with mixed results. I need to vent the mold better to get it to fill. I don't know why I didn't do this earlier or how I got away with it as well as I did. 

I tried melting the yellow casting shot with mapp gas and still no luck. Oxygen is needed to get the temp hot enough to melt it. 

I wonder about all the comments on this forum about melting gold or silver using mapp gas if gold/silver is that much lower melting point than the practice shot I am using or if the amount being melted is much less. Maybe going from powder to bead is easier than remelting the bead again. Maybe it just takes a long time to melt it. All I got was glowing metal beads that softened a bit but did not liquify. 

As far as lost wax casting, is it possible to do this work using gravity to pour the metal into the mold or is spin casting or vacuum casting the only ways to fill the mold? I would like to give lost wax casting a try to get more detail and more complex shapes than is possible with the sand casting but I can't justify the expense for the special tools I have seen used on youtube videos. Maybe if I built it myself?


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## qst42know (Jan 6, 2009)

This outlines the most basic form of investment casting, steam casting. Including making the tools needed.

http://www.myheap.com/book/chapter-08A/dnorris/Lesson_01.php


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## bmgold (Jan 6, 2009)

THANKS for the link. That looks like exactly what I need. I didn't read it all but it looks good.

edit: I looked at all of it (quickly) it IS good.

Oh yea, I gotta learn to read. The bottle of Mapp gas says don't use it in a normal propane torch. I got the right torch and even propane will melt the yellow casting shot. I'm a bit slow but I do learn.


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## goldsilverpro (Jan 6, 2009)

On that same website there's a well thought out gas crucible furnace. The guy even made his own blower.
http://www.myheap.com/projects/gasfurnace/gasfurnace.php


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