When I solder copper with silver solder, the seam is silver. Is there a copper solder I can use or something to fix this?A :
Yes, there is such a thing as copper solder that plumbers use. You can purchase it at some hardware stores and online. It is called copper phosphate. Upon research, I found many people had a hard time using the solder and getting it to flow. Best results were found using an oxy-acetylene torch. Color matching was also a problem, so seems are still visible.
There is another, easier option: Create a copper plating solution out of your pickle.
The first step is to solder your copper with silver solder. Continue to make your piece, hammering, filing, sanding, polishing, etc until the piece is finished to your liking, except for the silver solder seam(s).
To make your seam copper color, you will use your pickle solution to copper plate the piece. Simply place a nail or any other object that is steel or iron in your pickle. And you’re done!
So how does this work exactly? When you use your pickle, normally, it is taking off the black oxidation (copper) off the surface of the soldered piece. Tiny copper ions are then in the pickle solution. When steel or iron is introduced, it creates a reaction making the copper ions swimming in your pickle want to attach to anything in the pickle. Thus, copper plating whatever is in the pickle. The copper ions are so small that any filing, polishing or any other surface treatment will come off once the piece is plated. But because they are so small they imitate the surface that they are plated onto.
If you do this, be sure not to use any iron or steel that has rust on it, it will forever contaminate that batch of pickle. That being said, if the iron or steel is clean, your pickle is reusable, so make sure to take the nail or other object out of your pickle before you use it again. Also, the more you have used your pickle the better this process will work. A new pickle solution will not have any copper ions in the solution to plate the piece.