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Firescale on silver


#1

Just reading Charles Lewton Brain’s very informative article on
Firescale.

As a workshop largely devoted to production of silver jewellery, we
minimize firescale by annealing in copper tubes and little pots with
fitting lids.

Because copper is very hungry for oxygen at heat, the copper grabs
all the oxygen before it can reach the silver. The tubes can be
stopped with copper lids or a charcoal plug. All you then get is a
bit of superficial yellowing from (I assume) nitrogen.

I know of no other jewellers using this practice, (unless I told
them…), and have never seen any reference to this practice in
textbooks.

We use this approach on a daily basis with great results. Of course
you cannot do this when soldering, but removing scale from the
annealing process effectively halves any fire. Gold can also be
annealed in a similar way, without discoloration.

We use a flat copper ‘bag’ with a copper lid for annealing up to 30
ring blanks at a time.

It’s important not to heat the copper much past dull red, or bad
things happen when the metals melt into each other. -Disaster. I’m
always dismayed that people didn’t figure this one out a long time
ago.


#2

Torch or furnace. How do you know the silver is getting hot enough
to anneal? Can’t you pickle after annealing and have the same effect.