Are you sure they dont say SILVER FLO

Must have at least 8 Kgs of silver solder wire. which is very, very, slightly tinged a coppery colour, which does not rub off! I would love to know what it is. I suppose I could do a test to determine the melting point, But even if done accurately, would this be sufficient to make a positive identification?

Andrew.

I’ve seen strip called jewellers solder

Not sure if this is useful, but I used something very much like this at school, snipped into paillons, for silver soldering mild steel.

None of my books list “Silver-O”, so I guess it’s a long gone brand-name.  Doesn’t help my books list silver solders by their standard identifiers, only occasionally mentioning brand-names.

There are hundreds of Silver-solders, formulated for Steel, Copper, Aluminium, or to flow well, fillet, or gap-fill, at low or high temperatures etc.  Variants galore: for specialist purposes, made for cheapness, or to reduce the need for flux.   Seems the industrial countries all had several makers doing their own thing, and not many proprietary alloys survived.  Silver-O could be anything.

Michael’s suggestion of an XRF gun is best I think.  Many scrappies have them, as does anyone dealing in precious metals.   Not easy to identify silver solder from melting point alone as Andrew asked – they’re fairly close together.  In the old days, a conventional chemical analysis looking for the usual suspects (Tin, Cadmium, Indium, Manganese, Silicon, Phosphorous, and Copper) and carefully weighing.  The % of Silver is a strong clue.   Sadly, conventional analysis was already passée when I was at school, so probably difficult to assemble the wherewithal today.  Anyone own a chemical balance and a set of reagents!

Failing that try it.  If Silver-O doesn’t braze Steel, could be for Copper, or cast-iron, etc.   One of the common alloys will “just work” in the usual way, hurrah.  But it might take many experiments to find out what an exotic solder is good for.  If it doesn’t work like a common solder without fuss, I’d scrap it.  Might result in weak joints or be poisonous.   I’m all for recycling and saving money, but is it worth risking any job with an unknown solder?

Dave