Hello! Hope someone can help. I have lots of old 22ct yellow gold I want to reduce to 18ct. I am okay with the % of fine silver and/or copper I need to add, but any idea where I can buy fine copper?? A friend says a casters reluctantly gave her some a long time ago. Any other ideas?

Also how does adding copper/silver affect the flow/ pouring of the gold? I’m looking for the best flow over colour.

Any help would be fantastic!

Thanks!!