I've been using those commonly available 3kg electric furnaces, and they melt aluminum very well. They even melt copper wire very well... unless it's the more reddish copper wires which have that varnish coating over the copper.

When I put in a bunch of those red copper wires, the powdered black dross seems to all pile up at the very bottom of the crucible. I believe that this insulates the copper and prevents the copper from melting, especially since I can only take the PID to 1150C. So, I figure I start with as pure copper as possible - left over ingot pieces and raw copper wires. That melted very well. I added red copper wires to that and after 20+ minutes, it all froze inside instead of staying liquid - so, I think that the varnish still settled at the bottom. The copper in the crucible wasn't melted on the top, and poking it with a metal rod didn't compress or move the hard copper on top. I still added borax to the top but that didn't do much at all.



What is the best technique when melting these red varnished copper wires? Do I have to melt only a relative small amount of red copper wire at a time, pour, remove the dross at the bottom of the crucible, repeat until all the copper is made into tiny ingots, then melt all of those tiny pure copper ingots together? Or, do I need to add borax to the initial melted pure copper before adding the red copper wires?

Thanks in advance!