Change the color of solder to a copper color

Sounds like copper sulphate, Ron? Good luck with it.

A. I don't know of any chemical that changes silver to copper BUT there is a way that we do "copper plating" and it does work and that's steel wool [affil link on Amazon] and what the jewelry industry calls pickle acid -- turns anything copper really and it's cheap. Also use to be and I am having a hard time finding copper colored solder that would stay copper even after you heated it and soldered the project. When I first used it though I found it very hard to melt and it didn't hold up like I thought it should. Pickle acid is sold anyplace that sells jewelry equipment and is most of the time in powder form and you just mix it with hot water according to the amount needed. Steel bailing wire & steel wool [affil link on Amazon] are cheap and work well, and afterwards use a spray fix or clear gloss to keep it from chipping off at any time because it's not really a heavy coat that will last to things like patinas it with liver of sulfur [on eBay or Amazon] or any ammonia [on eBay or Amazon] very well.

A. It is copper patina available at any stained glass supply store. It is sold under different names and makers, but it's all copper patina. It is a blue crystal-like solution, and is very inexpensive.

A. To color silver solder a copper color try "Copper B Metal Coating" made by Sculpt Nouveau. They also make a "Copper C Metal Coating" which is applied a bit differently. Check their website for more detailed instructions.

A. The copper sulphate mixed with a little water can be applied to most solders to turn a solder copper color. When the mixture is still wet you touch the area with a bit of iron or steel and the solder will be covered with a coating of metallic copper. You can use this process several times until the desired color is obtained.
Roy

A. The "Blue Crystal Chemical" is likely copper acetate [affil links]. It can be made at home with some simple ingredients.

You'll need white vinegar [in bulk on eBay or Amazon] and 3% hydrogen peroxide in equal amounts in the glass jar. Do not fill more then 3/4 full. Heat the mixture to approximately 100 °F (about 30 seconds in the microwave should do). Then take a piece of your copper scrub pad, submerge it in the mixture and stir with a plastic spoon. It'll start turning blue. Remove the copper when it gets to a medium blue.

You can then use this mixture to electroplate nearly anything that's conductive.