What is annealing?
According to the Tim McCreight’s classic jewelry making book, Complete Metalsmith, “Annealing is the process of reducing stress within metal by heating to a prescribed temperature.” Tim refers to metal here, but this definition also is true for glass. There is also some helpful information in Preston Reuther’s Wire Sculpture site’s glossary of terms.
Why is annealing necessary?
In the case of glass, such as lampwork beads or fused glass pendants for example, proper annealing is necessary or the glass can eventually shatter. For metal, there are a few reasons to anneal. First, it relieves internal strains, which usually come from previous cooling. Another use for metal annealing is to soften the metal in order to make it malleable enough to work with, especially if it has been work hardened (stiffening or hardening metal by bending, hammering, or stretching it).
How do I anneal metal plate or wire?
You can soften metal (such as wire and plate) by heating it either with a torch or kiln and then quickly cooling, normally by quenching it with water. Again, I’m going to refer to the Complete Metalsmith for more detailed information about annealing metal.
How do I anneal lampwork beads and fused glass jewelry?
For glass, things work a little differently than metal because it’s already hot when you’ve been working with it. As an example, if you’ve fused some glass jewelry components in a kiln or just used a torch to make a few lampwork beads, then you are now working with hot glass, so you have to figure out how to cool it slowly. Lampworkers do this usually with a kiln that is already preheated. Fused glass artists have it a little easier because the glass is already in the kiln. By venting the oven (opening the lid or door a crack so it brings down the temperature to about 1000 degrees F), you then just need to close the lid and leave it to cool on its own. Arrow Springs has some detailed glass annealing information on its web site.
How much heat and the length of time needed for annealing depends on the heating element you use and the overall size of the metal or glass piece. However, the above information is a general overview of the process.