Alloying Copper into Lead-Tin
It's so easy it should be illegal! After reading and talking and looking up on the 'net, I decided to try adding copper to an already pretty good pot of alloy which is presumably lead-tin.
I took a piece of copper I had, tinned it with soft electical solder and submerged it into the melt. The melt has Kitty Litter on top and I fluxed with a stick, leaving a carbon rich layer close to the metal surface. The copper dissolved into the melt and that was it!
End results - benefits or changes? Well, the casting seem harder than before and also seem to harden quicker. There is no loss of ductility. The most noticable difference is the color of the sprue plugs. Very colorful whereas before they were shiny silver. There is a slight difference in the appearance of the castings but only slight. More than that, I don't know. I'll see how the castings harden or toughen or even soften over time.