Black Patina Staining Clear Glass

by Poppy
(Ireland)

Hi There.

I wonder could you help me with a problem. Having made, washed and dried two copper taped soldered stained glass windows, I applied black novacan patina to the soldered seams wiping it off as I went and then rinsed the windows in warm clean water. I almost immediatly noticed that the patina has stained the edges of the clear glass around the solder seams with an oily unremovable shadow, it has only occured on specific pieces of glass front and back and only on the clear glass.

I'm pretty sure that its not from flux residue as the windows were cleaned properly at every stage. Could it be that the flux has etched in to the glass and resulted in patina staining? or a reaction between glass and patina or water ph? or something else entirely???

Any suggestions much appreciated
Thanks,
Poppy

Answer

Hi Poppy,

Occasionally you'll come across a glass that does that. Usually it's irridized glass, but not always. I don't know why it happens, but I have seen it more than once. My guess is a chemical reaction between something on the glass and the patina, but like I said, it's just a guess.

The good news is that I do know what should remove the stains. Toothpaste! It has removed stains on glass that nothing else would touch. Just put toothpaste on a soft cloth and rub over the stains. It will take some serious rubbing, but it should work.

I have recently read that mineral spirits will also remove stains. I haven't tried it, but it is an alternative to the toothpaste and worth a try.

If the toothpaste ends up removing some of the patina on the solder lines, put contact paper on the glass that stains before you re-patina the piece.

If anyone reading this knows the reason why the staining happens, or knows of another way to remove the stains, please let us know by using the comments sections found below.