Questioni have been working silver and gold for for quite a while now but still have not come up with a good way of finishing sterling silver without it going black after a while(tarnishing). i am aware that there is argentium silver now but if i still want to work the old sterling silver alloyed with copper, what is the best thing to do to ensure that the silver will maintain its white luster much longer? what would be the best working procedure from start to finish. is there any chemical or so i might be leaving out in my process. i always use borax/ boric acid mix when soldering. when casting i use oxy/acetelyne but doesn't the oxygen in this mix contribute to the silver absorbing oxygen and thus assuming some sort of permanent fire stain?
AnswerGreetings,
Sterling Silver will always tarnish after some time, however there are a few ways to avoid this happening.
In the first place you can ensure that the piece is highly polished and thoroughly cleaned after completion.
The finished piece could thus be wiped over with furniture polish or floor polish and then cleaned by hand. Often this light coating of invisible wax will avoid oxidation.
I have found that once the material has excised its surface copper oxide then it is less likely to do so again.
You may be aware that there are several 925 silver recipes available, however only 925 Fine Silver 75 Pure Copper can be referred to as Sterling Silver.
I have had a very good result with 20Zinc925Ag55Cu, which has the ability of remaining white especially after casting. It is however not quite as hard.
Unfortunately there is no easy solution to fire scale, its just one of the by-products of soldering, heating etc.
You could talk to your supplier and see if they will supply you with 935 Silver, which has always been a great material for silversmithing.......and it stays quite white.
Your best bet is to always apply even temperature, etch or pickle in clean solution and clean totally after polishing.
Good Luck, P
