Also I am glad to be able to add a little to a John Burgess
comment (and perhaps also a little proud, - as John's comments
always are very correct and informative, - are you a chemist or
chemical engineer yourself, John?).
When we talk about oxidizing of silver (and the like) actually
we are not oxidizing the metal but giving it a layer of metallic
I Have used liver of sulphur and some of the other sulphur
products for the blackening of silver and similar, but
eventually I found a chemical manufacturer here in Denmark, who
makes a special solution for the purpose.
The label says: Selenium oxidazion liquid, and according to same
it contains: Selenium (Se) abt. 2,5 pct. in the form of
sodiumselenosulfide (or -sulphide), abt. 5,0 pct. It is a water
solution, quite caustic, but with a low toxicity.
The colour obtained is ranging from pale grey to deep black with
no hint of the brown which you might see using potassium- or
My first one litre bottle stayed alive about two years but then
died, probably because I dropped some silver in it and forgot
about it. My second litre is now on its fifth year and still
very well functioning. It is kept in a plastic jar in the shop
with no special precausions to light and/or humidity, and I
simply dip small items directly into it or paint it on larger
items, - here it is imperative to use a nylon brush.
When you paint - or dip - you can dilute the liquid with up to
ten times the quantum of water. This will give you a longer time
before your metal will be coloured. I have found that a 2 : 1 or
3 : 1 solution gives you the best results and, by the way, that
the colour obtained by the Selenium-liquid is longer lasting
than any of the ones mentioned in John Burgess' comment.
If anybody wants to go further into the subject, I can only
recommend Richard Hughes and Michael Rowe*s "The Colouring,
Bronzing and Patination of Metals", ISBN 0-500-01501-5, Thames
and Hudson. It contaions 69 recipees for colouring silver and an
innumerable number of recipees for copper, brass, bronze and the
like, - but by the way they do not mention potassium selenium
Hope this helps for you, it has for me.
Niels L=F8vschal, Jyllinge, Denmark
phone (+45) 46 78 89 94