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Deplating


#1

G’day, all; It occurred to me that I hadn’t mentioned another
use for deplating, which I call electro-chemical pointing. Now
I, like many amateurs buy my sterling wire in one size (2.5mm, in
my case) and draw it down to whatever sizes I need for the job in
hand, time not being so important when one isn’t making a living
out of jewellery making.:smiley: I hate putting the wire in a groove
in my bench and filing it to get the reasonably long point that
will go into a drawplate hole - and last for two or three
draws.So I keep a cyanide solution (in a tight-lidded, small
plastic container, boldly labelled) and a bit of stainless steel
connected to a piece of wire. I use a battery charger giving 6 -
12 volts DC and connect the stainless to the NEGATIVE terminal.
Another bit of wire is connected to the POSITIVE terminal and
has a crocodile clip fastened to the free end. This I clip to
the piece of sterling wire to be pointed, and switching on the
current, dip the end of the sterling into the cyanide bath,
jiggling it up and down, but keeping the end mostly in the bath.
Thus one has good control of the deplating or erosion process,
and can make the point as long or short as one wishes. In my
case, this process takes only about 10 seconds as I tend to use a
fairly high current, and after wiping on a bit of tissue after
rinsing quickly in water, I can do several passes before having
to repeat the process. But, you ask, what’s the advantage? Well,
it is fast, it doesn’t work-harden the wire and you can recover
the silver from the stainless electrode easily by peeling it off
after several pointings. Dangerous? Not really if you take
obvious precautions and keep the brain firmly engaged in gear
all the time. I’ve been doing it for about 15 years now.
Cheers, and have fun, eh?

    /\
   / /    John Burgess, 
  / /
 / //\    johnb@ts.co.nz
/ / \ \

/ (___)
(_________)


#2

PERSONAL

G’day, Kenneth; It is quite a while since I bought any cyanide,
so I can’t tell you much about prices, especially in the US, but
very roughly, most potassium salts are about 3 times the price of
the sodium salts, but of course this would depend on the chemical
too. For instance caustic soda (sodium hydroxide) is dirt cheap
because it is made for a whole swag of industrial uses, and in
quantities somewhere of at the very least, 1000 tons per day.
But caustic potash (potassium hydroxide) although having some
commercial uses, is not in great demand. So it is about 10 times
the price of caustic soda. Then the metal potassium is more
rare than sodium too. Incidentally, neither are ever found as the
metal and the pure metals are incredibly and violently reactive.
But sodium cyanide is used for a good many things commercially,
so is very cheap too - if you can get it. Pharmacies and
chemical supply houses are suspicious of ordinary folk wanting it,
and cross-question one as to what uses for which it is intended,
and make you sign a poisons register. In rural areas some farming
supply houses supply it for poisoning pests such as possums and
wasps. Electroplating is a very legitimate use, and if one
shows knowledge and confidence when applying for it, they will
usually let one have some. The stuff isn’t all that dangerous
providing common sense is used and the brain is kept in gear.
As this is my 76th year, my jewellery making, (and indeed other
making) is starting to tail off. Although I do keep my hand in
and completed a pendant in NZ jade and silver and turned up a
little box of NZ wood to present and keep it in only yesterday. I
used cyanide then for pointing sterling wire to draw it to the
size I needed. But I will be writing about electro-chemically
pointing wire in a note to Orchid shortly, so look for it there.
Does all this help? Cheers,

        /\
       / /    John Burgess, 
      / /
     / //\    johnb@ts.co.nz
    / / \ \
   / (___) \
  (_________)

#3

John:

Thanks for the additional info. I’m sure glad you didn’t quit
the list. What would we do around here without you.

Kenneth Gastineau
@Kenneth_Gastineau1