It would seem that if excessive temperatures were to be avoided,
that the technique you recommended earlier - melting pure copper
and then adding tin - would not be advisable. Pure copper melts at a
much higher temperature than any bronze: 1084 Celsius or 1983F
according to this handy char
Every time you alloy different metals this will be an issue. Low
melting metals will be over-heated. This cannot be avoided. What can
and should be avoided is heating patterns where problems associated
with over-heating are aggravated. The only way I know, is to melt
metal with highest melting point first and add the rest, as close to
the time of pour as possible. Incidentally, it is not only true of
bronze, but of any other alloy as well.
Today’s posts reminded me of something regarding the ‘ancient
bronze’: I melt with a hydrogen torch with a rosebud. Hot as hell,
and very reducing if you know what you’re doing with it. Just FYI. An
oxy-acet torch with a rosebud or cutting head will melt it with no
problem. (just make sure to wire the cutting handle up and out of
action if you use a cutting head. Do NOT hit that O2 jet!)
I don’t know what the person meant about it being scummy when
molten. It shows clean for me.
My normal flask temp for it is about 980 F. Haven’t ever had an
incomplete that didn’t have other issues.