First off I'd like to say this is a great site!
Currently I'm repairing a "Bronze" statue cast in 1880. I want to weld a stainless frame within the base to improve the anchoring system to the stone pedestal. I've got tons of experience welding silicon bronze castings and have repaired other odd alloy bronze statues with silicon bronze rod with good results (always dcen). I know old statues were not made of silicon bronze but it has worked in the past. I'm not sure but I think older bronze had a lower copper content more like 88%. Some old foundries poured any yellow metal that would melt.
This particular casting seems to not flow with silicon bronze rod. The base metal is 1/4" thick and seems to require more heat than silicon bronze to puddle. Once the puddle is formed it wont take the silicon bronze rod. I was going to weld the stainless stock to the bronze statue with bronze rod.
Whats the best way to approach unknown copper-based alloys?
I've got naval bronze rod as well as something called architectural bronze rod and some aluminum bronze rod as well. I seriously doubt this thing is brass but ya never know.
it might just be brass. It sounds like a problem I had a while back trying to weld some brass castings using aluminum bronze filler.
but I used AC with helium mix because DC was too scummy.
if you have the ability to mix some helium with the argon , that might be the ticket with AC current.