One of the first lessons in jewelry making involves the concept of work hardening and annealing metal. The most commonly used example to illustrate the concept is the familiar experience of bending a paperclip wire back and forth until the metal finally snaps. The wire starts out flexible so what makes it eventually break? The answer is work hardening.
Many jewelry makers have felt the effects of work hardening. Sometimes you can break a headpin or a piece of wire when repeatedly trying to get a coil just right. The breakage is not due to bad metal sheet it has just been work hardened by too much movement.
Work hardening is not always terrible. I purposely work hardened this claw pendant to show cracks in key locations on the pendant, for instance, around the claws and the edges. - Erica Stice
Bending, hammering and shaping metal wire or sheet puts stress on the metal. Those tasks are actually moving the molecules in the metal to a point where they are no longer able to absorb pressure. When this happens, it will literally crack or break the metal.
Annealing Sheet Metal
As you are working a piece of metal, you will feel when it begins to resist alterations as it work hardens. The good news is that most jewelry metals are easily softened or "annealed" to make them workable again. In fact, you can go through many cycles of work hardening and annealing on a single piece of jewelry.
The leaf pendant shown above, was heavily work hardened to achieve the final result. It was fold formed, rounded & shaped, textured, filed and cut, which put tremendous strain on the sterling silver sheet, therefore I annealed the silver 4-5 times just to prevent any cracks from forming. - Erica Stice
When you feel the sheet metal start to work harden, immediately anneal to avoid breakage. Annealing silver metal too soon will not be a big problem but waiting until it is too late may cause irreparable damage.
Steps to Annealing
To anneal a metal you must bring it up to a critical temperature with a torch and then quench the hot metal in water. Be careful not to heat metals beyond the annealing temperature or they will melt. A good guide, to prevent this from happening, is to use a permanent marker on the metal sheet. The mark will burn off near the annealing temperature of copper and silver, then you know to stop heating and quench it.
- Place your work hardened metal on a safe soldering board or charcoal block.
- Take a permanent marker and use it to draw a line on your metal sheet.
- Take your torch and set it on the largest flame that you can.
- Heat the entire piece, otherwise the parts unheated will remain work hardened.
- Turn off the torch as soon as the marker line disappears.
- Immediately quench it in water.
Note: Dry your piece thoroughly after quenching it, water can damage your jewelry tools if it's not completely wiped off.
Watch the video below to see how quickly metal can be annealed.