A while ago, there was a thread about soldering silver to stainless
steel. The consensus was that it is doable with the right flux.
Well, I thought you might appreciate an update. I noticed that Indian
Jewelry Supply carries “Black Flux”. I ordered a jar-- and it is,
indeed, quite black. Anyway, using it, I was able to solder a thick
(c 3-4mm) steel tile an inch square to a sterling band, as a friend
had asked me to do. I had already tried Handi flux, borax, cupronil,
batterns, no luck. My one additional bit of “wisdom” is that in spite
of using boric acid fire-scale protection, I ended up with a LOT of
fire scale, except where the black flux was. So this might have
potential to protect from fire scale in other situations. But, in any
case, next time, I’ll coat the whole thing. (Insert brag: I very
rarely get firescale any more, in normal circumstances.)
–Noel