ANNEALING METAL FOR JEWELRY
What is annealing, and why is it important?
When metal is hammered, bent, stressed, or otherwise “worked”, the molecules of the metal are pressed more closely together, causing it to lose flexibility. This is known as work-hardening. While we hammer our metal for jewelry, the metal will become progressively harder. If we do not stop to soften, or anneal, the metal, it will crack or split. Pieces may snap off. Stay aware of your metal, and anneal frequently when working.
How will you know when it’s time to anneal?
- Listen to the sound when you are hammering. Soft metal makes a duller thud than hard metal, which makes a higher pitched, more ringing sound.
- Feel subtle differences in how your hammer reacts to the metal. The hammer sinks into softer metal, and bounces sharply off of hard metal
- Watch the shape of the metal change. Soft metal changes shape, becoming flatter or longer, responding to the pressure of the hammer. Hard metal will keep its shape and resist changing.
- Test the metal by trying to bend it when you notice the above signs of work hardening. If the metal is hard, springy or difficult to bend, STOP hammering and ANNEAL the metal.
Setting Up an Annealing Area
On your work bench or table, create a fire resistant surface.
Some ideas are: several large ceramic floor tiles, sheet metal (try to be sure not to use zinc-plated sheet metal, this can be hazardous to your health when heated), masonite, cement board, etc.
On this surface, set up your area with:
- a fire brick, soldering pad, or other safe, heat-reflecting surface
- insulated tweezers (cross-locks are a good choice)
- A bowl of water
- Torch (a high quality butane torch is fine, as long as your metal is small enough, no more than about 1” x 1”)
How to Anneal
1. Mark your metal with a permanent marker (such as a Sharpie) or a dab of jewelry flux (Handy flux and Dandix are common brands).
2. Place hardened metal on your chosen surface (fire brick, etc).
3. Light torch according to manufacturer’s directions. If your torch uses both fuel and oxygen tanks, you can adjust the flame so that it is soft & bushy rather than sharp and hissing.
4. Begin by warming the metal gently across entire surface.
5. Bring flame in closer until the point of the blue cone is about ¼ inch from the metal. This is the hottest part of the flame.
6. Continue to move the flame constantly across the entire piece, evenly raising the temperature of the entire piece. Don’t stop the flame on any one area.
7. When the marks you made disappear or the flux turns first white, then clear, you are near annealing temperature. Watch for changes in color that indicate annealing temperature has been reached. This is a difficult state to describe. If you have not annealed metal before, I suggest you turn off the lights and watch the metal as you heat it. When it begins to glow pink, you have generally achieved annealing temperature for sterling silver. If you can get someone to turn the lights back on at this moment, you will see that the glow is not quite visible. There is, however, a particular look to the silver at this time. With practice, you will be able to “see” this internal glow and recognize the changes in color that indicate that annealing has probably occurred. Sterling silver should not get much hotter than this temperature or you will risk melting it. Copper and brass (or bronze or Nugold) should be heated until their glow is visible with the lights on. Copper should glow gently, while Nugold should be made to glow brightly to anneal well.
When you have reached annealing temperature, back the flame away from the metal somewhat, but continue to heat it gently, maintaining annealing temperature for about 60 seconds to fully anneal the metal. If sterling starts to glow so that it is visible in normal room light, you have usually exceeded the normal annealing temp, so pull the flame back and heat more gently for 60 sec. Brass needs to be annealed for longer than copper or silver, so keep it glowing for 60 -120 sec.
- Things to be aware of: Wire will heat and anneal very quickly, and it is safer to coil the wire to protect it from overheating. Sheet will take longer than wire. The thickness of the metal (gauge) and the size of the sheet or wire will make a significant difference in the annealing time.
- What happens if I heat too much?
With copper and brass, there is rarely a problem. Both are difficult to melt, and it’s nearly impossible with a butane torch. Overheating will cause more oxidation (discoloring), and drive it deeper into the metal, that is usually the worst that will happen.
With silver, both oxidation and melting are potential problems. Before silver melts, it begins to get a shiny, liquid silver look to the surface. If you begin to see this, you have raised the temperature of the silver well beyond the annealing point, which may create unwanted textures and brittleness. I strongly recommend melting a piece of scrap silver and carefully noting the changes prior to melting. Once you have seen them, you will begin to recognize the signs, and may avoid damaging a piece you hope to complete.
- If noting color changes just doesn’t work for you, just watch the sharpie disappear or the flux turn clear. Increase heat a bit more, then pull the torch back a little to keep the heat at annealing temperature for 60 or more seconds. Cool and quench.
8. Once the metal is annealed, remove the heat and turn off the torch.
9. Allow it a few seconds to cool a bit, carefully pick up the metal with your insulated tweezers, cross locks, or tongs, and quench it by dipping it fully into the bowl of water. Don’t be alarmed if it hisses as it quickly cools, this is normal.
10. Remove the metal from the water (it is cool enough to touch almost immediately) and dry. Wet metal on your steel tools is a quick road to rust, so be sure to dry well.
11. Check for softness by gently bending the piece. If fully annealed, it should now bend easily*. If not, anneal again, allowing the metal to get slightly hotter and hold for a longer period of time.
Congratulations, you have just successfully annealed your metal!
(*EDITOR’s NOTE: “bend easily” can be a relative term depending on the gauge (thickness) of your metal – keep that in mind!)