Making Bronze, Reaching Limits
This time we tried to make bronze, in a ratio of about 90% copper to 10% tin (396g and 38g). Depending on its alloy, bronze melts at around 950º C. But since we wanted to make the bronze ourselves, we had to go about 150º C higher, because copper on its own melts at 1085º. (Tin is no problem since it melts at 232º C.) According to our pyrometer, we had reached over 1100º C in other melts, but with only one pyrometer it's not possible to get really accurate temperature readings throughout the furnace. So we couldn't really be sure that we could reach that heat inside the crucible, and maintain it. Jorge lit a little fire in the furnace, we added charcoal about halfway up, and then added our loaded crucible. Everything started well as usual; the temperature climbed quickly. We were having problems with the pyrometer though; the wires were coming loose and it would cut out from time to time. Pretty quickly, as the temperature rose higher, we started seeing beautiful, entrancing wi...