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Handmade hollow chain


#1

Have heard of larger firms making lovely large hollow curb bracelets by
drawing down the gold with a steel core and then soaking the chain in an
acid to eot away the steel upon completion. Does anyone know if this is a
possibility in a small workshop or does it involve specialist equipment,
Regards Johnny the Jeweller


#2

I never heard of this process but I have removed broken drill bits from
14kt gold by soaking them in nitric acid. Nitric acid will not attack 14kt
or higher. I don’t see why you couldn’t do the process you described excert
for the fumes involved and the acid waste. Frank


#3

Denise and Johnny,

I have heard of hollow link chains being made with an aluminum core.
After forming, the aluminum is dissolved using caustic soda (lye). Any
soldering would have to be done after the aluminum is completely removed.
Steve

Steven Brixner - Jewelry Designer - San Diego CA USA
mailto:@Steven_Brixner4
http://home.att.net/~brixner


#4

john,

it’s possible to make a hollow gold chain this way in a small shop. wrap
your tubing around a copper wire, coil it and cut it, and soak it in a
nitric acid bath…it may take a while. the only thing you will need is
adequate ventilation. and be sure that you cut each link cleanly, since
it’s hard to adjust the hollow rings later.

doug zaruba


#5

Sure, it’s possible. But don’t use steel. Hard to form chain with a
steel cored wire. The core makes it possible to bend the tube you’ve
formed without it collapsing. Start by making a suitable gold tube (You
don’t need seamless tube. In fact, if you make it a tube with an
unsoldered seam, the core will dissolve out quicker.) Fit into it a
suitable core wire of copper or bronze, or aluminum or even silver. Draw
again until the tube is tight to the core, and reduced to the desired
diameter. Bend to your desired links after carefully annealing (don’t
overheat it. You don’t want to melt the core to the gold, and the contact
between the two will melt lower than you might expect) Keep track of where
the seam in the tube is, so it’s on the inside of the bends. You can
solder the links shut with the core in place, if the seam in the tube is
slightly open. If it’s really tight, you’ll have to leave the links
unsoldered for now. The gold tube may be discolored by dilute nitric, but
won’t dissolve. But a copper, bronze, or silver core will dissolve in the
nitric. Copper will also dissolve in Hydrochloric acid or sulphuric acid.
None of these will do more than discolor the gold if of about 12 K or
higher. It might need to soak in the acid for a while to get all the core
out, depending again, on how tight the seam in the tube is, and what
core/acid combination you’re using. If you used an aluminum core, the lye
(sodium hydroxide) will remove it, or so will HCL. Note that all the acid
etchants are more effective when diluted at least 50 percent or more with
water. Concentrated acids, surprisingly, sometimes etch slower than
diluted ones. for nitric, a 10 percent mix is great.

Hope this helps.

Peter Rowe


#6
Note that all the acid etchants are more effective when diluted at least
50 percent or more with water.  Concentrated acids, surprisingly,
sometimes etch slower than diluted ones.  for nitric, a 10 percent mix is
great. 

Peter,

The “full strength” nitric I have is 70%. A 10 percent solution of this
concentration would be adequate?

Thanks,
Pam


#7
  The "full strength" nitric I have is 70%.  A 10 percent solution of
this concentration would be adequate? 

yes.

Remember that most acids are not actually liquids. They are often gasses
dissolved in water. Your 70% nitric is about as concentrated as it can be
made without it becoming an unstable fuming acid (which by itself, degrades
back down to about that 70% concentration as acid fumes off).

Peter