Annealing copper wire

I started annealing my own wire. I have found it to be fairly easy and well worth the effort. I’m not the best at making videos but check this one out it could be useful to some other members with a few tools in the garage.


Thanks for sharing! For my understanding, you do not or must not cool the wire rapidly by putting it into cold water?

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I have been led to believe that air cooling is best. Some people choose to cool the copper down in water. I suppose I could experiment myself and see if I can see a difference in the results.

@MartyWeiser a Mirai member, wrote this piece on annealing copper wire some years ago.
It seems everyone has a different way of cooling down the copper, but the main reason to cool with water it to remove the oxidation. If you skip this process you will notice when wiring, small particles of oxidation will be released from the wire into the air where you are working. :grimacing:


Cooling quickly softens the copper allowing it to work harden as you use it.

A good read. Do you quench copper after annealing?

The heating is what softens it not the cooling.

Take note… the black copper oxide coating is slightly unhealthy… lungs and injested…
If you do a lot of this work, or wire with the oxidized copper… gloves and a mask… wash your hands and face after use, too.


Thank for the advice. I wonder if a quick soak in some evaporust or a similar product would eliminate this problem.

As a side note I see alot less oxidation on the wire I heated in the forge as opposed to using a torch. The forge fire has a very low oxidation rate as the air must pass through the fire pot before reaching your work. Even with steel if you are using to much air or not enough charcoal you will ruin whatever you put in there very quickly.

Epovo-rust website says… this product doesnt work on brass, copper or aluminum… the chelating agent apperantly only works on iron oxide…? Looks extresmly safe for that, though…
Use what you got… be aware of the side effects. At least a mask, if you do a lot of wiring; do it outdoors!
Probably, ONLY way to eliminate the black oxide…is a non oxygen heation system… a electric kiln with nitrogen outgas…?
Also, if you water cool, be aware that the water now has the oxide, keep your dog and kids out of it…
One side note… I dont use copper on roots for tiedown. Its a poison… I DO use it on purpose for drainage screens…, it keeps the drain clear of roots… kills them when they get too close… Also, keeps bugs from entering–galvanic shock… iron tiedown + copper + ionic water carrier (re-- battery / shock…)!
Aw, yes. Better living through chemistry!
Bonsai On!


That IBC post that Brent put on his site is from 1997 which dates me a bit (my first IBC post was in 1994). In addition to the heavy oxidation with slow cooling you can end up with weak wire due to growing the grains too large by either holding the wire at temp to long or very, very slow cooling. Neither of which are common. I still like the water quench of copper wire to get rid of most of the surface oxide.

Copper has two primary oxides. Cu2O is red and CuO is black. Cu2O contains less oxygen so it is what is on the surface after quenching or cleaning of the surface and allowing the wire to sit for a little while. CuO contains more oxygen and therefore takes more time to form - either a high temperatures during cooling or over months on the tree.


Yes, the heating makes it soft, but faster cooling actually does make it even more pliable (softer) as opposed to just air cooling. The work hardening afterward isn’t affected, as far as I know.

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I’m glad to be having this discussion but I am struggling to find any evidence that there is any advantage to quenching the copper after heating as it relates to softness. Maybe someone has some if so please add it to the thread.

I do see that pickling is a common practice among jewelry makers as a method of removing the oxidation after an annealed item has cooled. If you don’t know pickling like the name suggests is soaking in a mild acid for 24 hours or so. This is something I will try adding to my own process.

Have you tried any of this last batch of wire? Is it butter soft along the legnth?
I found manually passing the wire through a spot heat source leaves uneven annealing sections. I have done a coil of wire in a high heat barbeque successfully… still left black oxide.
Most of the copper wire I have bought had black oxide.
Occupational hazard, I guess.:roll_eyes:

It seems quite nice to me. I know that forge fire is burning in excess of 1000c and is 6" wide. It will easily heat a 1/2" bar of steel to yellow hot in no time. I’m pretty sure the wire was adequately heated.

The whole point of doing this for me was to take something that was relatively worthless and turn it into something of value without investing more than time and effort.

So maybe my methods and results aren’t perfect but I was kept busy for an hour and I have what 60 dollars or so of usable wire. I count it as a win.


Watch out with a temp of 1000C, melting point of copper is 1083C as mentioned in Marty’s article.


The quench does not soften the copper. Heating above 800f does.

Quenching cools rapidly and allows the scale (oxidation) to pop off the wire.

Soaking in vinegar will also remove scale.

Source: I am an industrial heat treater.


This is a bit off subject but still in annealing copper, I kiln annealed wire for the first time, I brought the temp to 1500F with a 500f /h ramping, heating was stopped after reaching target temp and allowed to cool naturally in kiln as I do with ceramics. Is this a good approach? And how can I improve?


I suspect that you will end up with a lot of oxide scale on the wire. It should work well but when you bent the wire, the scale will puff off and can be inhaled.

You just need to exceed 750 - 800F. The heating & cooling rates will not affect the physical properties. The scale can be removed with an acid bath such as vinegar (pickling).

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@John3 Do you recommend dilution of the vinegar with anything? Or pure vinegar?