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Hardening silver in a kiln?


#1

I know you can anneal silver in the kiln, but it seems that somewhere
I have read that it can be hardened in the kiln also (more than when
you tumble it). I have looked through my books and can’t find the
reference. Can anyone point me in the right direction? Is it possible
to harden .999 fine silver in a kiln too?

Thanks for any info,
Louise


#2

First you can search the orchid archives, the search terms to use are
"age hardening", “precipitation hardening” and “heat hardening”. They
all are the same thing, but they are not all mentioned together in
the literature. The best written reference for you to get is
Brepohl’s " The Theory and Practice of Goldsmithing"

http://www.ganoksin.com/jewelry-books/us/product/961598492.htm

Not cheap but has lots of other you will use. Here the
subject is called age hardening-- metallurgists will call it
precipitation hardening. The process requires an appropriate alloy –
a pure metal won’t do.

jesse


#3

Louise,

Sometimes with sterling. And a very good temperature controller is
needed. My experiments years ago with an old analog controller were
less than exciting, my present digital one has much better control.
Might be worth an afternoon of play.

From a google on precipitation hardening sterling
http://www.mjsajournal.org/features/0502

Sterling Silver. It is recommended to solution treat sterling
silver at 750 C to 760 C/1,382 F to 1,400 F for 30 minutes,
quench immediately, and age for one hour at 300 C/572 F. The
hardness of the sterling alloy can be effectively doubled with
this process, from HV 60 in the fully annealed state to HV 120. 

The only problem posed by this process is that the solution
treatment temperature is above normal soldering temperatures for
sterling, so only articles with no solder can be treated.
Soldering after hardening sterling will over-age the material
dramatically to the point of nullifying the hardening effort. 

Jeff
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#4

Check out my article I put in Orchid a few years ago about tempering
Sterling Silver & 14K gold in my electric furnace. Your temp
instrument should be accurate to 2 * F

Yours Billy S. Bates