Annealing silver is the process of heating the silver to make it soft enough to work with. You may have to anneal the silver several times during the making of a piece of jewellery, because working with the silver makes it hard again.
Most of the silver I buy from Cooksons comes ready annealed, but I still anneal it frequently during the making process using my gas torch. I move the torch over and over the surface of the silver as it goes from light whitey grey to dark grey and then glows pinky red. I don't cover my silver in flux before annealing as some do, I just anneal it bare. As soon as I see it turn glowy pinky red, before it begins to melt, I pull the torch back and just maintain a gentle heat for about 30 seconds, then remove the torch and quench the silver in water. If it's the final anneal, I will then pickle it to remove the oxidization, otherwise I keep working and annealing and quenching it until I am finished, and then I pickle it. I especially like to anneal a piece before I texture with a hammer, as the hammer marks are smoother and softer on annealed silver.
Working with the silver, that is hammering, sawing, bending, rolling, causes it to gradually harden again and this makes it less flexible. If you keep on working it without annealing it becomes brittle, and if you are bending or folding it again and again it will eventually crack and break, so frequent annealing is essential.
Sometimes a piece of silver becomes soft when you want it to be hard, and it can be too late in the making to work harden it some more. In these cases you can use a tumbler.
For example, many of my rings have thin hammered shanks. I hammer the silver wire on my ring mandrel before I cut the final length as hammering stretches the wire and you can end up wasting precious millimetres. Then I have to heat the piece to solder the join which can soften it again. Apart from hammering over the join, I don't want to hammer it anymore because it is now the size I want. Then I have to heat it again to attach the bezel or flower, or whatever else I am fixing to it. You can hammer it with a rawhide, or nylon mallet which will harden it a little, but not enough to make it hard-wearing. This is when a tumbler can be really useful.
Mine was given to me second hand by a friend. It's actually a National Geographic rock tumbler aimed at children, and came with little packets of sharp stones, gems and some polishing compounds
I bought some stainless steel shot,
and some soap flakes.....
....and used it for the first time last week. What a great little piece of kit! I put in a large handful of shot, enough water to cover it, half teaspoon of soap flakes and then whatever jewellery I want to harden or polish
The hammered rings come out beautifully hardened and shiny after only 30 minutes tumbling. I keep it in the garage on the freezer where it can't drive anyone mad with its whirring noise. It doesn't have a short timer (only 1 day, 2 day etc) so I set the oven timer so that I don't forget about it. Because the shot is stainless steel it shouldn't rust and can be used again and again.
I like to oxidize most of my jewellery with liver of sulphur so I do this after tumbling then hand polish afterwards.