I made a video that shows how to anneal thin copper wire. The same method can be used for silver or brass and for thicker gauge wire. Thicker wire should be kept in a tight coil with the use of binding wire.
I use a honeycomb soldering base and a white soldering block, but you don’t need both. Even a heat resistant tile with some charcoal on top will do.
The wood surface of my table is protected by a sheet of steel in case hot metal falls off the soldering block. I have heat resistant bricks around the soldering area to concentrate the heat and avoid accidents.
The torch I use is a Clarke Weld mini torch, that I ordered from the UK, but any torch will do. Remember to keep the flame relatively low to prevent wire from melting, and keep the flame moving. The point is to heat the whole surface evenly.
After heating the wire I place it in a warm acid bath for a few minutes to clean the metal. I use safety pickle in an electrical container that keeps the temperature steady but a glass container over a heat plate will also work. Just remember to turn off the heat when you see vapour coming. The acid will burn if it gets too hot and will become worthless.
I use a soft toothbrush to wash the wire because I don’t want to harden it again with too much scrubbing. For sheet metal, which doesn’t have that problem, I use a brass brush.
Here’s the video: