I tried the same liver of sulfur "Patina-Gel" as marketed here in the USA by Cool Tools (
www.cooltools.us ). I am so glad I experimented using copper British pennies instead of my good cups. Not because it was injurious, but I'd have to remove the natural patina off of my cups that the cups and I earned earned.
I found the product quite lacking, as far as achieving a natural looking patina. On British pennies, it made them look a ghastly dark greyish color. I removed a bit of the false patina with a jewelry polishing cloth and was careful to have it just remove the patina from the raised areas on the coins. That looked better, but coins aren't cups.
My 3 week old set of RNT II Paul Fox mini cups have a patina that is to die for. To think that this patina came with only 3 weeks of handling is amazing and goes a long way in saying how pure the copper that RNT II uses is. They went from normal looking polished copper to a very distinct red color in a week. The next 2 weeks have brought about very dark colors in every part of the outside of the cups except the little area between the flared rings and bottom, turned lips.
I now have a bottle of Patina-Gel in the back of the cabinet I use to hold cleaning products. It won't be used again. You just can't beat a natural patina, especially if you start with copper of the highest quality.
My verdict is as yours, Patina-Gel is only for fooling unknowing buyers of products that they think are aged and well used (in the case of our Magic cups). The reality of actual aging is far more glorious. Would that we aged as well naturally too! ;o)
dsalley13