For those of you who might not want to waste your time and money, after having used Griffith silver\black and liver of sulphur, I recently tried lime sulphur, Bonide, Lime Sulpur Spray, calcium polysulphide 30%, and was entirely and completely disappointed with it. Liver of sulphur is sooooo much easier and faster.
If its speed that your looking for; I use a product for Indian
Jewelers Supply called WINOX the stuff is superfast. You just paint
it on with a brush (that has no metal) and as soon as the brush
passes over your piece you have black in under one second. Its cheap
and lasts a long time. I bought my 8 ounce bottle several years ago
for under US $10.00. There is one major drawback however the stuff
contains a very very nasty chemical and when applying it puffs of
poisonous smoke arise; but it is so fast that I just step outside
and sit on my back porch when I use it. Even outside the stuff is
noxious. It is about the only time I wear rubber gloves and should
probably put on my respirator. The black is a decent dark color other
have mentioned to me that its is not as long lasting as LOS but I
have not found this to be such. I make a few pieces that are almost
solid black (not just antiqued recesses) and find the patina to last
very well without waxing or lacquering the item.
Good Luck and hold your breath. Mark Kaplan