A passion for silversmithing

STERLING SILVER : Noun, meaning silver of 92 and a quarter percent purity.....

Tuesday, 21 August 2012

Annealing and work-hardening sterling silver


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.

6 comments:

  1. Very interesting - I enjoyed reading about annealing and I have always wondered what a tumbler looks like!

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  2. Why do you quench the silver when annealing it? That hardens it. Quenching is how you temper soft metal. Better to let it cool slowly, surely.

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  3. PS: I like the tumbler idea. I figured it would be a better way to polish than jeweler's rouge but I never considered that it would work harden the pieces too. Good Kit Indeed.

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  4. Quenching does not harden silver. Quench away.

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  5. Quenching while hot IS how you temper soft (and hard) metals . . . which is the point. To temper it at lower temperatures softens it and make it less brittle. If you heat the metal above the critial point and quench it, THEN you end up hardening it with tempering/quenching.

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  6. I'm confused by the terminology - when working with steel the structure changes above the critical temperature and if you quench it , you freeze the structure and harden it. You call tempering the process by which you heat the hardened metal to a precise fairly low temperature to reduce the brittleness and choose the right combination of ductility and hardness. If you heat above the critical temperature and cool slowly, you anneal the metal by letting the structure reform as it cools - this gives its softest condition.
    This suggests that you are either hardening or annealing the silver, not really tempering it at all.

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