It's not so much the white gold, that I can fix/replace. It's the
using acetylene that sends me over the edge.
Paf, maybe I misunderstood, but wasn’t the situation a platinum ring
where the sizing had been done with gold solder, adding a gold piece?
Given the much lower temperatures for this; at those soldering temps,
the platinum would not be harmed by acetylene, nor would the platinum
develop pits or the like from it, since the platinum never gets
anywhere near it’s melting point, or near any temp where it might be
absorbing carbon or other stuff from the flame. So any problems
you’d see would be in the gold solder, and that, I’m assuming pits in
the solder seam or the like, can result with any of the fuel gases,
with acetylene being no more likely to cause them, when working with
gold solders. I’m thinking the problems, if any, in such seams would
be simple poor fitting of joints, not proper cleaning of the metals
and solder, dirty flux, overheated solder, or any of the other
various reasons solder joints can be pitted. Did I miss something?
Or are you referring to other jobs, done with the otherwise proper
platinum materials, but still pitted or faulty, which you’re chalking
up the acetylene use?
It does occur to me to mention that oxy/acetylene, while a poor
choice for working platinum, can actually be used if you have no
choice. If the flame is set sufficiently oxidizing, then there will
not be free carbon left in the flame when it hits the metal, so
problems can be avoided. And even if this isn’t done, if the metal is
very clean, so there are no traces of silica (in fluxes, soldering
pads, even just house dust where silica may be a part) on the metal,
then the free carbon in the flame won’t actually cause problems.
I say that because my understanding of the problem is that carbon
itself is not what contaminates the platinum, but rather, at those
temps, carbon is able to reduce the silica (silicon dioxide) down to
the metal, silicon, which then can be absorbed/diffused into the
platinum, and it is these traces of silicon added to the platinum
alloy which is actually the cause of the pitting and brittleness seen
in such situations… It is the combination of that free carbon at
high temps, and the virtually ubiquitous presence of traces of silica
everywhere, that gives rise to the problems. I first heard this
explanation in a paper presented at the Santa Fe conference something
like 25 years ago, I think, and it makes sense. It nicely explains
why contamination problems with platinum can be caprecious, sometimes
appearing, and sometimes not, even when apparently the same mistake
is made. If I’m wrong in this and someone knows better, please