Can anyone help me?! I can’t get my silver to melt in my crucible. I use an acetylene and air tank, and I have no problem melting silver with my torch anywhere else…except in my crucible (fully prepared with Borax). Silver is clean.
Thanks for any help!!!
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It just takes a lot of heat. Preheat the crucible, build a little tent of heat resistant material around it, turn off the fan if you have one nearby. I use propane and O2, but have used propane and air for a small melt. I also have an electric melting furnace that works very well. Keep on trying, but remember that it takes a lot of heat. Good luck…Rob
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Rob is correct. It takes a lot of heat to melt silver in a ceramic crucible. Two important variables are how much metal are you melting and what size tip are you using?
For instance, it will be way easier to melt 1/2 oz of silver, than it will to melt 1+ oz’s.
As far as the size tip, if you have a Smith Air/Acetylene torch I think you’ll need a #3. The #4 is bigger, but can be unstable unless you have the gas turned to the proper pressure. See the instructions for the proper pressures.
Also, I think you know this, but you need to preheat your ceramic crucible to the temp where the borax flux melts before you put the metal in. The metal will melt faster that way.
Hope that helps!
Jeff
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if you have a Smith Air/Acetylene torch I think you’ll need a #3. The #4 is bigger, but can be unstable unless you have the gas turned to the proper pressure.
Tank size matters. Do not use large tips plus large flames with an MC tank.
One should not draw too much acetylene out of solution at a time. Pressure in the tank drops too fast, even more acetylene comes out of solution, it can get circular and run away on you.
I had a fitting on the tank side of my regulator crack and leak gas and acetone when using a Silversmith torch and a #4 tip. The tank was outdoors. You especially do not want that to happen if the tank is strapped to your soldering bench inside.
Neil A
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Thanks so much to everyone. Much appreciated!
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I have three torches that I run. A Prestolite plumbers torch for annealing and two Smth Little Torch’s with fixed regulators and an O2 generator for everything else. My melting is done with Propane and O2 and a Paige MX melting tip. I just melted 65.3 grams with no trouble and I suspect it would handle 20. Grams more. It may take awhile to dial in the O2 pressure but with the time.
I really recommend the Paige MX tip for any steady heating applications. Butt I run a fairly primitive shop.
Don
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Good catch! I never use MC tanks. Jeff
Ive been looking at those tips. Do i need to buy the adapter?
haven’t had a problem because of using a oxyacetylene torch for cutting steel… high heat output… heat output matters more than temperature of combustion… all gases burn at much higher temperatures with air than the melting point of silver…had have trouble using air/propane… not because of the temperature but because of the crucible… deep crucibles cause blowback, reducing the amount of heat reaching the bottom where the melt happens… if your tip has enough of a heat output… (temperature of acetylene air is very high, used it also)…and if your crucible is deep, try blowing the flame down one side rather than directly straight in… the blow back will be unidirectional and will allow the flame to hit the silver. Pre heating the crucible also helps a lot …another option that avoid the problem is using a melting dish… I’ve used a casting crucible, a deep one and a shallow melting dish…all of them work, but it takes getting used to.