Question: Annealing

[RES]

What is the proper, or best way, to anneal copper ? Green gold ? and pink gold ?
I'm not sure that I'm getting mine, as soft as, possible.

Robert

 

[silverchip]

Most non ferrous metals are annealed by heating and then cooling rapidly unlike steel.If I am annealing silver I coat it with a slurry of boric acid powder and denatured alcohol and using a fairly soft flame from a torch heat it until it is a very light salmon pink color in low light.At that point quench it in cold water. If it still seems to be a bit springy,just repeat the process and it should be good to go.I know there are some specifications for different alloys available that would give you the proper temp.ranges for different alloys but generally speaking I use the same basic method for copper,silver and karat gold.

 

[RoycroftRon]

Copper is the easiest, just heat it until it glows medium red in light then quench in water then put in a pickle bath to remove oxides. If you let it go too hot or long it will get grainy and be prone to cracking. Gold will depend on the alloy, but treat it like silver to be safe. For silver and lower karat golds I do the same as silverchip explained in his post, and coat the metal with a deoxidizing flux. When heating silver or lower karat golds I heat with a low reducing flame with the lights out and look for the metal to become a dull red. Then quench in water and put in a pickle bath to remove oxides. For gold that is more pure I just heat it until it glows and push it into a waiting bath of alcohol to pickle.

 

[Dulltool]

What is a pickle bath?

 

[RoycroftRon]

For the non ferrous metals you can remove the oxides by using a mild acid. Sodium bisulphate is the active chemical in what I use, it's the pool chemical that lowers the ph in your pool. I use about one cup of dry chemical to a 20 gallon tote of water. Be careful of the fumes when mixing, and it is a skin irritant so wear gloves. Another product sold by rio grande and others is sparex, but the pool chemical seems to clean better for me.

 

[thughes]

Here's a really stupid question. Why do you anneal silver? Be gentle.

 

[silverchip]

I have annealed silver for some operations including spinning and raising as well as chasing and deep drawing.

 

[GTJC460]

Here's a really stupid question. Why do you anneal silver? Be gentle.

All metal hardens as you work it, like when rolling sheet or square wire or when drawing wire down. Basically any time you hammer, bend, or draw down the metal makes it get hard. There's a point you can't take it any further with out the metal cracking or splintering. Just before this point is when you need to anneal it. The annealing process makes the metal soft again so you can continue working it.