Annealing restores malleability to work-hardened metal. Work-hardening is due to the compression of the crystalline structure of the metal, making it rigid. If the metal is rigid, further working can cause it to crack or tear. The easiest way to return the metal to a workable state is to anneal it.
A typical annealing station should have:
- Fireproof surface (firebrick, charcoal block, or a soldering pad). Some jewelry suppliers sell a device called an annealing pan, which is filled with a pumice medium.
- Two glass dishes with water
- Pickle pot with pickle
- Copper tongs
When working with sterling silver, flux the metal before annealing it. Sterling silver is vulnerable to firestain, a particularly resilient form of heat-induced oxidation.
Set your metal on a fireproof surface. Use the torch with a bushy, reducing flame to heat the metal evenly; keep the flame moving until the metal glows a dull (for silver) to cherry (for brass or copper) red. (It’s easier to see if you dim the lights.) When the piece reaches that color, remove the flame. Use copper tongs to quench the metal in water, then place it in the pickle for about five minutes. Rinse the metal in a second dish of water.
There are some common tricks that will help you tell when your metal is annealed:
- Watch the flame instead of the metal. When the flame changes from blue to orange, the metal is annealed.
- Make a mark on the metal with permanent marker; when the mark disappears, the metal is annealed.
- Paint a bit of paste flux onto the metal; when it turns clear, the metal is annealed.