Annealing is the term for softening metal so that it is malleable. The process involves heating the metal and then cooling it. Cooling the metal can be achieved through air cooling, quenching and sometimes both.
Sterling silver is heated to a dull red(900F). Let it lose its redness and then quench in cool water. (Presto you have soft metal). There are a few steps before you can heat the baby up.
The metal should be coated in a protective substance called a “Barrier Flux”. It is made up of boric acid and 91% isopropyl alcohol.
Many people use denatured alcohol. I discovered it’s toxic and the human body does not metabolize denatured alcohol. This means it doesn’t leave your body very easily once you have absorbed it. Kind of scary. That is why I recommend 91% isopropyl alcohol because it’s less dangerous.
The 91% isopropyl alcohol burns off nearly as well as denatured alcohol. I do not recommend the 70% isopropyl alcohol.
You can mix the boric and isopropyl solution 50/50 for a thicker solution. This will provide a nice thick coating for your metal. This is good for annealing. If you are soldering you can use 25% boric and 75% isopropyl alcohol.
Use a glass jar with a lid. I use an old pickle jar or you could use
a mason jar. The lid will keep the alcohol from evaporating.
*Tip (If you try to anneal after you have soldered, your project may fall apart at the solder joints. Plan ahead and perform this step before you solder your piece together)
Step 1. Make sure all metal surfaces are free of dirt and grease.
Step 2. Gently shake up your solution and dip your metal into the jar.
Step 3. The metal piece must be coated with boric acid and isopropyl and fired.
Step 4. Heat the metal to a dull red. Keep it at that temperature for a few seconds.
Step 5. You can quench it in water or let it air cool on your solder pad or steel bench block.
Step 6. After it has cooled you need to remove the boric acid that is on the metal. During the heating process the boric turns into a glass like substance. This glass protects the metal from fire scale. Fire scale is a coppery color that appears on silver and gold if it has been over heated. (You will find out that fire scale is a bummer) You can soak your metal in a pickle solution or warm soapy water.
Pickle solution is a strong acid that quickly removes boric. It is usually heated in a small pickle pot similar to a small crockpot. The pickle solution should be used in a well ventilated area. If you choose to use it read all of the safety instructions. It is a serious acid and shouldn’t be taken lightly. Many of the goldsmiths I know use an ultrasonic cleaner with soapy water. It works great and is very safe. Here is one a good one on Amazon. There are a few different sizes so pick the one that is right for you. I usually get one that is a little larger than I need so I can grow into it.
Step 7. Clean the metal with an old toothbrush and rinse under water. Inspect the metal for any boric glass that may still be attached. If it looks good you are ready to start making your masterpiece.
This is a basic look at annealing. For more information on annealing, here is another good article.
Here is another about fire scale that is helpful to know.
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