I can't melt 1oz ofSterling
Hello, I joined the forum because I cannot bring 1 ounce of sterling silver scrap to a flow point so that I can pour a 1 ounce ingot of silver.
1. 32 g of acid tested sterling. The silver was cut into small pieces.
2. A silica crucible bought on eBay from FindingKing jewelry supply.
3. BurnzOmatic propane torch model TS 4000.
4. Prograde propane fuel.
5. Two syntax butane micro torches model number, SX 2050.
6. Titanium stirring rod.
The crucible has a round bottom. So I set it on a 1 1/4 pound cast-iron weight with a hole in the center. The crucible fit perfectly on it. First I tried a flux of straight Borax and water. I added too much water so the water boiled and turned the Borax to a consistency of cottage cheese, when it finally melted it looks like black lumps. Next I tried a 50-50 mix of Borax and boric acid. This time I use less water, and I made a mixture to a consistency of dough. I still had some water boiling, but eventually, the flux melted and turned smooth black.
I put the 1 ounce of sterling scrap. On top of the melted glassy flux and began heating, first with one micro torch. Then with two micro torches this will not bring it to the proper melting temperature. So I changed over to the propane torch.
The highest temperature I can reach on the silver is to a bright maraschino cherry red and and silver will not melt, although it will fuse the parts together. The corners of these pieces have rounded off and the lump is fuse together. The crucible has reached a bright orange color. I have seen bright green flames coming off the silver as the copper burns off. Most of the green flames have now stopped.
I thought maybe the cast-iron weight was absorbing heat from the crucible. So I held it in the air with tongs but no good results. At this time, I have used nearly a full can of propane and over 1/2 hour of heating time. I realize a second can is not going to melt the silver.
Can anyone please help me to understand why I cannot melt the sterling silver. I realize that there is a problem, but I cannot identify it.
Last edited by Byzantine : February 4th 12 at 05:02 AM.