Silver cement not melting! New blowtorch needed?

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NewBullion said:
I washed my remaining cement I thought was clean, because when washing it with H20, the water ran clear eventually. I put 200g into a filter, packed it down, poured in boiling tap water, and watched this yellow fluid drip out. Some small particles fell through into the cup, looks like cement, but it's orange. Guessing this might be copper.
Click to expand...
Guess again! 8)
I think you'll discover that if you put a drop of HCl on the yellow material, it will dissolve instantly, and yield a hint of green.

It's iron.

Rust.

Harold
 
Thank you, Harold. I am certain your advice on torches will benefit not only myself, but also New Bullion and others who are trying to find the right way to get things done. I do not have gas service at my home but I can certainly buy a combo torch rig at Lowe's or Home Depot. In fact, I will be doing so tomorrow as I am wasting time and MAPP gas with my current set up. I have heard many people say that MAPP, propane, propylene and even butane fuels work well for melting silver, but in my experience they do not. I have tried 3 of the 4 with limited success and it is frustrating. I believe the cost of the oxygen will even out with the use of less MAPP because of quicker melt times. Even if it does cost more to run a combo set up it will be worth it just on the time I will save on the many, many melts and castings I plan on doing. I will look at torches with interchangeable tips, including a rosebud.
 
Many years ago I bought a National 3A torch (usually called "blowpipe") for almost nothing. They are about $100 and have been made since the 30's, unchanged since then. I just bought an assortment of 5 tips for $28 on ebay, some oxy-fuel and some rosebuds. These torches, depending upon the tip selected, can use nat'l gas + compressed air, NG + oxygen, propane + oxygen. I am a tad concerned that the neck of the torch is a little short and might cause my hand to feel a lot of heat, especially under oxy+fuel use, but we shall see. They can even use NG at "house" pressure" which is very low.

I have tried using MAPP gas to melt silver and I simply don't see the feasibility. I see people melting metal in YouTube videos but I have never been able to do so in a way that makes me happy. And MAPP is expensive. You shouldn't have to spend 10+ minutes heating your work. If you do, you're underheated. I have *never* been impressed with MAPP gas. Plus, with a gas + air torch, you really do not have the opportunity to produce a reducing flame which as Harold pointed out, is handy for silver. I have read the specs, intellectually I know MAPP dumps lots more BTUs into a piece of work than does propane, but it has never floated my boat.

national_torch.jpg


If I didn't have this torch body, I would probably recommend a new buyer purchase a brand new light-duty oxyacetylene set, including regulators, but to run the thing on oxygen and propane. Which just means selecting the proper tips. Plenty enough heat The fitting into the fuel cylinder USED TO BE the same, between actylene & propane but may not be any longer, as propane tank-fittings have changed over the past few years.
 
I agree that the length of that torch may be somewhat undesirable. It will likely serve well for small volumes, but I'd hesitate to heat several ounces, and I definately would not recommend it be used to melt palladium and/or platinum.

Nice torch, by the way. Too bad it's not somewhat longer, to get you away from the heat.

Here's a picture of the torch I used to use, to give you an idea of how long it should be to provide comfort. Sorry for the cluttered picture, but it's the only one I have.
Ingot molds.jpg

Harold

Upon edit: You may be able to use an extension on the brass body, moving the tip out. That's all that would be required to make it a fine torch. Looks like it would be easy to make.
 
There are plenty of rosebud type tips on the National (Premier industries) torch site, even In stainless steel.

The tube for their hydrogen torch version is much longer than the standard torch. They do sell extensions.

http://www.nationaltorch.com/tips.html

http://www.nationaltorch.com/Tipexelb.html
 
Yes, National sells all kinds of everything for the torch, but you will find their prices very expensive, particularly for individual pieces. The torch body alone is $100, that's with no regulators or hoses or tips. In any other circumstances I would not be going this route except I bought the torch body with a NG + air rosebud brand new unused for like $3 at a garage sale...I couldn't resist it. The 5 tips I just bought on ebay for $28 are about $14 each * 3 qty and $25 each for 2 rosebuds.

I would just buy a smallish oxy-acetylene set complete with regulators and hoses and be done with it. That's what it looks like Harold has. You can buy a complete US-made set for under $200, handle, tips, hoses, regulators, brand new. I'd also suspect you could find a very lightly used set with medium-small tanks for very little more than that. I think it is only the cutting and rosebud tips that are different for oxy-propane vs oxy-acet. I would try to do research as to what the manufacturer of any used (or new, for that matter) set offers for propane, where can get them, and what they cost. Pretty easy. And as I said, you might have to change the input stem to the fuel regulator if you want to use propane. The fittings used to be identical propane > acet but they have changed just in the last 5 or so years.
 
I was at trade day this morning and saw a guy with complete set ups for acetylene for sale. They were used of course but in good condition. $200.00 would have gotten me the cart, the bottles, regulators, 50 ft hose, a striker, and the torch with my choice of a new head. A deal anyday !!
 
That's a good bit better than a typical deal, but there you go. With a lightly used rig, you can get a cart and those tanks "thrown in". You may have to buy a tip or two, but if you do, then those are nice and new. You'll almost certainly have to buy new oxy-propane tips for any rosebud work and to cut steel if you change the regulator over to propane. The cart is a VERY nice thing to have, not just because it helps move the tanks around, but it makes it easy to tie the cylinders to an upright so they do not fall over in use. That can be extremely dangerous, a tipped over oxygen tank whose valve gets knocked off will turn into a torpedo and can blast through a concrete block wall. Needless to say, that could cause serious injury. One way or another, be religious about tying up your tanks!

Also important: Make sure that there is a date stamped into the oxygen cylinder that is within the last 5 years. If the tank is "out of test date" then nobody will fill it without testing it. If it is close to the expiration of the test date, then it may be smart to take it to a gas supplier and exchange tanks even if it isn't empty. Don't let your oxygen tank get out of test date.

Second, and there isn't a wonderful way to do this, ask the seller if the tank is an "ownership" tank. This means that the seller basically owns it and brings it back to the gas supplier and takes away an equally-sized, filled tank, but a DIFFERENT tank. What you want to find out is whether the tank is stolen, but you have to ask delicately. Just ask "where do you get these filled". Probably answer: "Any gas supplier" = meaningless. Try to ask in a way where you find out if the seller ever had the tank refilled and what it cost.

Acetylene tanks generally do not go out of test, since they are rather low pressure. Smaller tanks do NOT have the screw-on safety caps. I always preferred the minimum size that had those safety caps on them. Yes, they could be 3 lifetimes of supply for the small PM guy, but safety is something we talk about around here and I am big time in favor of it.
 
In Denmark the rules are strict and the prices disgustingly high when oxygen and acetylene bottles are concerned.

LPG on the other hand, is no problem as long as you do not go above 11 kilo bottles.

I have been doing all my gold and silver melting with an LPG burner (Sievert cyclone burner) of the type used by plumbers to hard solder copper tubing.

When you want to heat something, you need to have:
- temperature But that is really not a problem: A candle flame is easily 1100 degrees centigrade, any burner flame is warmer. They should all do the job, right? But no;
- wattage: And here is the first problem. Your burner needs to deliver more heat than is lost from your target. The radiation energy per unit time from a "blackbody" is proportional to the fourth power of the temperature. In plain speak that means, that once your target is glowing, you loose a lot of heat. In a furnace, the radiation is kept inside, but in a melting dish, you need to put in a lot of heat!
- concentration of the heat: In my opinion, this is where oxy-acetylene (and oxy-LPG) wins: It makes a small concentrated, hot flame. A traditional LPG-burner is too fuzzy. The cyclone burner is hot and concentrated. It is not as fast and hot as the oxy-acetylene, but it does a nice job.
 
goldenchild said:
juxtaposedsoul said:
Too much time melting silver. Great point Harold, not just for me but for anyone spending a lot of time over the melting dish. A new torch has just went to the top of my list. One minute to melt an ounce? That would be awesome and well worth the money spent for a new torch. I'm guessing that an oxy/acetylene torch would also make it easier to pour the silver because it would stay molten a little longer?
Click to expand...

On my youtube channel there is a video of me melting and pouring 10 troy ounces of silver with MAPP gas. So oxy/acet will definitely do the job. There is also a video of me shooting silver using an oxy/acet rig. I chose the rig that time because the metal has to be hot enough not to freeze in the receiving crucible.
Click to expand...

I know this is an old message and this is probably not the video goldenchild is talking about but it explains about why silver doesn't melt when using a propane torch and shows how to do it.

[youtube]http://www.youtube.com/watch?v=ZFPZK0w-gso[/youtube]

Trick is kaowool or ceramic fiber insulation. Lasersteve used to (and probably still does) sell a small firebrick furnace to melt silver/gold using a propane or mapp gas torch. Same idea...insulation.
 
Hi
I tried melting 400 gram silver cement for the 1st time. Not melting after 2 hour
I saw green flame so after one hour I added one spoon of Sodium bicarbonate on the melt and put it in the furnace again for another hour.

My furnace was red
http://uupload.ir/files/gov_img_20171128_171111.jpg

After 2 hour:
http://uupload.ir/files/n8bb_img_20171128_173158.jpg

http://uupload.ir/files/z3th_img_20171128_173713.jpg
 
From the color, it sure doesn't look hot enough to me. Silver melts at 1763F (962C). To give a little time to pour it, before it solidifies, I would heat it to about 1800F (982C) or so. On the temperature color charts, 1800F (982C) tends to be a bright yellow-orange color. Your photos show somewhere around a semi-bright red color, maybe with a little orange in it, about 1500F (816C), more or less. By eye, this color thing is not rocket science, but I think your melt is more red than anything. Pick your poison on these charts. None are perfect and no two are exactly the same.

https://www.google.com/search?biw=1138&bih=514&tbm=isch&sa=1&ei=U6YdWr6pAsvBmwG7o4ygCA&q=molten+temperature+color+chart&oq=molten+temperature+color+chart&gs_l=psy-ab.3...129602.144482.0.145233.17.17.0.0.0.0.158.2335.0j17.17.0....0...1c.1.64.psy-ab..0.7.1026...0j0i13k1j0i8i7i30k1j0i7i30k1.0.ZfvobcOJ300
 
Thanks
I couldn't reach to yellow after 4 hour!!! What is problem ?

Flame:
http://uupload.ir/files/ppcd_img_20171129_175716.jpg

Furnace: (After 2 hour I putted some glass wool in hole of the torch)
http://uupload.ir/files/2q7t_img_20171129_194514.jpg

It was orange tonight:
http://uupload.ir/files/yf21_img_20171129_185329.jpg

In youtube I see many videos of melting silver with a dish and mapp gass torch!!!
Why I can not melt with a furnace ?
Also my silver be shrink. Did it evaporate ?
 
Your just below the melting temperature. Your not putting enough heat (Btu's) into the furnace.
What you are seeing with the shrinking is called solid phase sintering and gives the clue to your problem you are asking about. The shrinkage is from the fusion process of the molecules where they move closer together almost becoming a liquid at the liquid solid phase transition temperature. Your almost breaking that temperature line of melting, but not quiet. The answer is either stop the excess heat loss or pump in excess btu's to heat the mass up. Just because you are reaching melting temperature with the burner doesn't mean it's pumping out enough btu's to overcome the thermal mass of the silver as a whole. A cigarette lighter flame burns hot enough to melt gold or silver, but the lighter can not produce enough btu's to overcome the heat loss or the combined thermal mass of the object your melting anymore than it can heat your living room. Silver metal clay is a sintered product. It shrinks 10-15 % on sintering without ever melting it. You can do it on a stove eye! It makes a solid without melting. Metal clays do the same thing. They do a lot of metals this way.
https://www.youtube.com/watch?v=hPUJPXyUt3c
 

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