I have several sterling bracelets that I need to heat harden. I’ve
never done this, since I don’t have a kiln. I was looking at the Rio
catalog’s advice on the subject, and they said I need to get the
silver to 600� F. for 30 to 50 minutes.
I will soon run the self-cleaning cycle on my electric oven, and 600�
is about the cleaning temperature. But it stays there for longer the
50 minutes, I think. Would it be at all feasible to put the silver
pieces in the oven? What would happen if it stayed hot for too long?
Well I finally tried the great self-cleaning oven heat hardening
method, and it worked like a charm! Talk about low-tech!
I had three sterling cuff beacelets, and after fluxing them
thoroughly, I put them on the steel mesh square from the soldering
tripod, and set it on the top oven rack. At the end of the cleaning
cycle they were nicely hardened.
I guess I come down squarely on the low-tech side.
WHAT?! What did I miss? How is this possible? I didn’t know it got
hot enough in my oven to do that. Do you leave the bracelets in the
oven long enough to complete the cleaning cycle or do you “break
into” the cleaning cycle?
Sterling silver can be harden dramatically by first annealing and
then submitting it to a one hour heat treatment at 600� F. The higher
the preliminary annealing temperature (up to 1350� F) the harder the
alloy. However, it’s dangerous to quench sterling at temperatures
above 1200� F. Therefore, it is recommended to follow this proceduRe:
1. Heat (anneal) the item to 1200� F
2. Quench immediately
3. Place in a furnace preheated to 600� F and heat soak for one (1) hour.
4. Bench cool
You can use an anti-oxide of boric acid and alcohol, but is does not
help that much in reducing the oxidation.
Many karat gold’s can be hardened through heat treatment. The degree
to which an alloy is hardenable depends on its non-gold component.
The type of alloy will depend on the final hardness.
1. Heat(anneal) the item to 1100� F - 1200� F"
2. Quench immediately
3. Place in a furnace preheated to 600� F and heat soak for two (2) hours
4. Beach cool
You can use an anti-oxide of boric acid and alcohol, it will help
some what in reducing any oxidation.