Patina or LOS
Is Liver of Sulphate the same as black patina? I have a bottle of black patina and is a light greenish blue color. I want to use it on a piece of copper that I etched with mordant. Can I use it? Many thanks.
I use Liver-of-Sulfur (potassium poly-sulphides and potassium sulphate) to get different black and brown patinas on copper and silver. There are a few black patinas available out there, but I don't know what your "black patina" is. Does the bottle have a brand name? There is a patina called, "Brass Black Metal Finish for Brass, Copper and Bronze" that is sort of a blue-ish color. I have used it on brass, but not on copper. It is commonly used for the bluing of brass on guns.
Etching a pattern on your metal first will not affect the patina process as long as the metal is clean before applying the patina. As I'm not sure of what you've got, I can't say if it will work...or not! :-) Test a disc or scrap of copper in the patina you have and see if you like the results. Can you tumble-polish it? Buff it with a polishing cloth? Or does the color rub or rinse right off? Some "patinas" are more like a paint coating that sits on the surface of the metal rather than oxidizing or patinating it.
If you're not satisfied with the results, get yourself some Liver-of-Sulfur to use on your copper and silver items.....works like a charm! The new stabilized gel form that I have in my Etsy store - www.hodgepodgerie.etsy.com - can be shipped via air as it's no longer spark-able. The nugget form is spark-able and must go by ground.