There are multiple types of "white metal" used for casting....while I don't know about what to add to solder to make it better for casting, but I do know that Micromark has casting metal ingots in their catalog....
http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action=Catalog&Type=Department&ID=122
Sure, none of it's "cheap", but it is interesting to see the different melting temps, and the mixes of metals used:
Type R lead-free Crown Pewter (92% tin). Melts at approx. 575 degrees F. Can be melted with propane torch
Type 280 tin/bismuth alloy; lead and cadmium free. Melts at approx. 280 degrees F
Type CT Almost pure lead. Melts at approx. 500 degrees F. Can be melted with propane torch
Type 160 tin/lead/cadmium/bismuth alloy. Melts at approx. 160 degrees F. Can be melted with a candle flame. Extremely low temp. allows this metal to be poured into molds of clay, wood, even cardboard. Can also be poured into model RR locomotives to increase traction weight.
http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action=Catalog&Type=Department&ID=122
Sure, none of it's "cheap", but it is interesting to see the different melting temps, and the mixes of metals used:
Type R lead-free Crown Pewter (92% tin). Melts at approx. 575 degrees F. Can be melted with propane torch
Type 280 tin/bismuth alloy; lead and cadmium free. Melts at approx. 280 degrees F
Type CT Almost pure lead. Melts at approx. 500 degrees F. Can be melted with propane torch
Type 160 tin/lead/cadmium/bismuth alloy. Melts at approx. 160 degrees F. Can be melted with a candle flame. Extremely low temp. allows this metal to be poured into molds of clay, wood, even cardboard. Can also be poured into model RR locomotives to increase traction weight.
