Annealing: how to soften metal

When metal is worked a lot it hardens and becomes brittle. Annealing restores its ductility by heating it and letting it cool or quenching it in water.

How it is done #

1. Clean the piece and heat it evenly with the torch.
2. Watch the color in dim light: a dark cherry red is the usual reference for silver and copper.
3. Remove the flame and let it cool for a moment.
4. Quench in water (for silver and copper) and pickle to remove the oxides.

When to anneal #

Whenever the metal feels hard, springs back or stops responding to the hammer, rolling mill or draw plate. In rolling, anneal between passes.

Firescale #

In sterling silver, the copper in the alloy oxidizes when heated and leaves dark stains under the surface. It is reduced with a protective flux, with a fine-silver surface or by using resistant alloys such as Argentium silver.

What to watch #

Do not anneal more than necessary: overheating can melt the piece. In gold alloys, time and temperature depend on the karat.

Step by step #

1. Clean. Remove grease and dirt from the piece.
2. Heat. Move the flame in circles, not staying on one spot.
3. Watch the color. In silver, a very faint dull red in dim light.
4. Let it cool. In air or quenched in water, depending on the metal.
5. Pickle. Lower it into the bath to remove oxide.
6. Rinse. Rinse and dry before continuing.

Tools and materials #

• Torch and firebrick
• Steel or copper tweezers
• Pickle bath
• A dimly lit corner to see the color

Common mistakes #

• Overheating: the metal melts or forms firescale.
• Heating only one part: it ends up uneven.
• Putting steel tweezers in the pickle bath.
• Quenching in water metals that do not allow it.

See also #

• Forging and hammering metal
• Rolling and wire drawing: sheet and wire
• Jewelry alloys: how they are made
• Pickling: cleaning oxides after soldering or annealing