Add 3-5 drops to warm water and place your piece in the solution. Keep it in the solution until it becomes dark. 
Please note that you must use raw copper or silver wire without any coating. The solution will only react with raw metal wire. This method will not work on colored craft wire.

Now we have to polish our piece. Polishing removes the patina on the high points and leaves it in all the depressions. You can continue to add and remove patina until you’re happy with the results. If you don’t like it, you can pickle the piece to start fresh. The finished piece should look warm and almost vintage. It’s always best to patina copper, as raw copper can look like plumbing pipes!