I was working on a stained glass panel recently on which I intended to use copper patina. The common wisdom is to use the copper patina immediately after you have soldered and cleaned the piece; delay results in black spots or blotches in the patina.
Unfortunately, I was called away just after I completed my soldering and clean up, and it was a few days before I could get back into my studio to work again. I was not looking forward to the problems I would face with my copper patina, so I kept putting it off. I procrastinated so successfully that three weeks went by before I forced myself to deal with the problem.
I searched the internet for answers and only found more reinforcement for the position that a decent copper patina simply could not be achieved even 24 hours after the completion of the soldering and clean up.
Hmmm . . . Bad news, but I was determined to go forward and make this work.
The decision regarding patina must be reached early on in the life of a project when the foil is applied. Depending on the patina selected, black-backed, copper-backed, or silver-backed foil is used on clear or cathedral glass where the backing will show through.
The panel I was working on included some clear glass and some light colored cathedrals, so the copper backed foil I had used (in anticipation of applying copper patina) would stand out clearly and glaringly, unless I could achieve a decent copper patina.
The reason for proceeding immediately is to avoid any oxidation or contamination which will spoil the result, so I decided to clean the soldered seams as much as I could.
I washed and scrubbed the project in dish soap and baking soda, and it looked pretty good. I then decided to make use of my Dremel. I experimented until I found a metal brush attachment that would clean up the solder seams without destroying them. I went over all of the seams carefully with the Dremel with the metal brush attachment. As a last step, I polished the piece with Kem-O-Pro Finishing Compound (probably any good polish would do,) and buffed it with the Dremel and by hand until no more black would come off and the piece was a shiny silver. That was a lot of work, but well worth it!
Finally, I applied the copper patina and dried the piece with paper towels. (Note: Do not wash the piece with water again. Water will discolor the patina and leave the spots and blotches we all dislike so much.)
Success! I had a rich clear even copper patina with no spots or blotches. Woo hoo!
The best scenario is to immediately patina, but if you encounter a delay, such as I did, be reassured. You can still achieve a beautiful copper patina. Do a thorough job of washing with dish soap and baking soda (to remove any flux residue,) and then polish, polish, polish. If you do not have a Dremel, just apply more elbow grease with your polishing. I believe that the most important step is to polish the piece until no more black comes off and it shines silver.
For more helpful hints on how to finish your stained glass pieces visit our Tutorials on the Web page and view the finishing section. Go forth and patina with confidence.