Making it more malleable.
Annealing copper sheet metal.
You can anneal any grade and thickness of copper as long as you have a flame that can transmit enough heat to the metal.
Copper is one of the metals that hardens when it is worked bent stretched.
Annealing is a technique that all metalsmiths will.
If all you want to do is color the copper a small torch will likely do the job but you are not likely to be able to actualy anneal any signifiacnt size piece.
How to anneal and firescale copper sheet metal.
This is especially so in metals that become work hardened like copper and brass although brass can become very brittle and fracture easily especially if it has been heated.
This malleability allows you to hammer and mold the copper into any shape you wish without cracking the metal.
In the case of ferrous metals such as steel annealing is performed by heating the material generally until glowing for a while and then slowly letting it cool to room temperature in still air.
This video shows you how to safely use the torches in this classroom as well as anneal a piece of copper and add firescale.
Annealing copper makes it softer and less brittle which allows you to bend it without breaking it.
Darlene armstrong director and co owner of the denver school of metal arts shows you how to anneal a sheet of copper using an acetylene torch.