Annealing (metallurgy) is the process of heating metal altering the microstructure of a material causing changes in properties. In metalsmiting its used for softening the metal so that it is more pliable, bendable.
While opening a soup can, have you ever had the lid of a can not cut all the way off and so you bent the lid back and forth until it broke off? This is the process of "work hardening." The processes of hammering, bending, or compressing metal work hardens the metal. Over working the metal causes it to crack or break. The metal must be annealed before it cracks or breaks and then the work process can continue.
Sometimes silver, copper or brass sheet comes already annealed and other times they are sold not annealed or hardened. If the metal is hardened it must be annealed before working the metal like bending or hammering. Annealing makes bending and sawing metal easier.
Once the metal is annealed it stays annealed until its work hardened. So, if you anneal metal and allow it to sit for years, it is still annealed. Time doesn't harden the metal.
The process of annealing is heating the metal to a specific temperature either with a torch or in an kiln. With a kiln you can set the temperature but with a torch you must watch the metal until it is a dull red color. The room must be darkened so you can see the metal's color. For beginners its had to see this. There are two easy ways to know when the metal is up to temperature.
- Place a dot of Handy Flux in the center of the metal. Heat the metal going from the outside edge to the center area, keeping the flame away from the flux. This heats the metal evenly and as it warms up the flux will dry to a white crusty look and then go clear. When its clear the metal is up to temperature.
- Using a permanent marker, draw a dot in the center area of the metal. Heat the metal going from the outside edge to the center area, keeping the flame away from the flux. This heats the metal evenly and as it warms up the black dot fades away leaving a shinny area. At this time the metal is up to temperature.
Here are the complete steps:
- Apply either flux or permanent marker to the metal.
- Heat the metal with a torch holding the torch perpendicular to the metal. Don't hold the torch angling it across from the front edge towards the back edge! This doesn't heat the metal evenly.
- Slowly move the torch across the metal going from the outside edge circling in towards the center. If you move the torch fast, it doesn't heat the metal evenly.
- After the marker or flux fades, pick up the metal with tongs and quench in water.
- If needed clean the metal in pickle and then rinse.