Will I ever learn? This orchid thing is like a drug...
(grin... don't i know it!)
Dear Mr. Rowe, If I understood it correctly, you are
recommending that small jewelry casters add a "pinch" of ammonium
chloride onto their melt under some general overhanging hood that
they may use to evacuate heat or fumes from plating or burnouts in
order to remove contaminants of "zinc, iron, and many others".
Well. Not really recommending. As you have amply pointed out, if
such contaminants are there at all, then the overall process needs
review. And, most likely, anyone casting larger amounts will
actually be reusing only cast metal, and these contaminants aren't
likely a problem. The problem is most likely found with folks
reusing things like scrap silver from fabrication, where small amounts
of silver solder, etc, may be introduced. That's the most likely, I
think, source of zinc. bits of broken saw blades, file teeth, and
the like, can introduce small amounts of iron. The situation is
most likely to arise, not so much with silver, where it's low cost
reduces the incidence of people slavishly reusing their scrap, or
needing to correct messed up metal. But for the goldsmiths, an
ounce or so of brittle metal can be a problem. Then the ammonium
chloride can be a real money saver. For most people, this is seldom
a problem, so the situation won't arise. But when it does, then a
small bit of ammonium chloride can help out, as a refining flux.
This idea, by the way, isn't one I came up with. It first came to my
attention in a turn of the century book by the (then) eminent author
on precious metals use in Britain, George Gee. He recommended
several such refining fluxes as ways to potentially cure certain
problems of, notably, brittleness in the metal. That applies to both
gold and silver alloys. Obviously, he was writing at a time when
authors did not have to assume all their readers were untrained or
idiots. I would like to also assume that though many orchid readers
may be less experienced, few are idiots. And her in orchid, there's
always the safety valve. If someone like me writes something that
some other reader feels understates the safety aspects, no doubt
there will be follow up articles to correct the oversight, for which
I thank you sir.
But I stress that this is NOT normal and frequent procedure, and
certainly not a routine thing to do. If you'll reread my original
mention of this, I wrote in large capital letters that this should be
done outside. Equivalent ventilation with a good hood might also
suffice. As you note, anyone doing this regularly will quickly find
the process quite noxious if they don't have proper ventilation.
And of course, a "pinch" is just that. A tiny amount. Again, if
anyone mistakes this word, and dumps in a whole bunch of the stuff,
they'll quickly find themselves rushing around opening windows and
leaving the area. I DID say the fumes were nasty, didn't I?
However in your response about the reuse of silver buttons I
feel that you may be answering a different question than the one
that was asked.
I may have strayed a bit, yes.
The following is the data on Powdered Ammonium Chloride in a jar.
46or the record, the little jar of ammonium chloride that I use
comes from a children type chemistry set supply. I didn't buy the
whole set. Just the refill jar at a hobby shop. That suggests that
at least a few folks aren't much alarmed by the stuff in that form,
as it's sold for use by the least informed chemists possible...
People should not consider the use of ammonium chloride as a
common step for the reuse of their sterling silver buttons. If
your casting and metal processing system is such that you may have
contaminants of iron and unintentional zinc then you may want to
consider cleaning up your metal processing and casting system
Agreed. But if you find yourself in a situation where you MUST
reuse some questionable scrap including some blobs of solder,
perhaps, then, well, perhaps this method is a useful one to remember.
Normal casting buttons need only a good pickling to remove oxides,
and a very good cleaning to remove all traces of investment.
The use of a 50/50 borax and boric acid mix should be more than
sufficient to remove the lighter metal oxides and minor residual
investment that may have been imbedded in your buttons and scrap.
Agreed. That mix is my preferred casting/melting flux. I'd stress,
as someone already did, (Jim Binnion, I think) that removal of traces
of investment make a big difference, as traces of that break down
into sulphur compounds that cause significant problems with the
metal, and unlike oxides that slag off to the surface with the
boric/borax flux, can remain in the metal.
Please know Peter that I have great respect for your
and God how I hate the petty one upmanship responses
that I see on this website from time to time. So please know that
this response comes from a man with only 65% of his lung tissue
remaining due to a car accident many years back and is very
particular about his lungs. I have also been in a jewelry cyanide
accident that landed me in the hospital at the ripe old age of 19.
To top that off I also had a very nasty experience from the
chlorine gas that was liberated from a "completely safe", Salt
Refining System (under a hood), that is still sold in the jewelry
industry today. Of course, I am older and wiser these days.
Cough, hack, etc... Others may say that I am using scare tactics
to make a point and my answer to that is, your damn right I am.
Well, right you are to be concerned with your own health, and that
of others. Scare tactics are not a bad thing, when used with accurate
info, which your's generally has been. thanks for bringing to my,
and the groups, attention, any impression that my little trick might
be considered routine, or cavalier. Hmm. I wonder if it's not then
such a good idea to note that when one's cyanide based gold plating
solutions are starting to give a somewhat paler color, that it may be
due to not enough free cyanide, and a pinch of sodium or potassium
cyanide added to the bath might considerably improve the color? Hmm.
No, I better not mention cyanides at all, I guess.
Best Regards with the Best of Intentions.
Likewise, with thanks.