Annealing Copper Wire Finally and Need a Little Advice Pls

August44

August44

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I have been collecting copper wire remnants for a year or so and want to get it annealed. I have been told that I can use an electric kiln locally but would like to get input on:

The highest temp that I should go and should I set the firing up with a hold. If so, how long should the hold be? The wire you see in the picture is what I will be annealing. There is some 14 gauge, some 13 gauge, some 12 gauge, some 11 gauge, and some 6 gauge. Also wanted to know why some copper wire I bought from one source starts to work harden when you start installing it, which can make it tough to say the least, and the second group bought from another source takes an hour or two to get hard. Is one over heated and one under heated? I don't want mine to work hard almost immediately, and don't think I want it to take two hours either. Any advice to keep me from screwing this up after all the work would really be appreciated. Thanks, August
 

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Typical temperature to use is 400C / ~700F for annealing.

August44 said:
Also wanted to know why some copper wire I bought from one source starts to work harden when you start installing it, which can make it tough to say the least, and the second group bought from another source takes an hour or two to get hard.
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Sounds odd. Copper that has been annealed gets harder as you bend it, immediatly. It is a physics process, not a chemical process.

August44 said:
which can make it tough to say the least
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One of the reasons why in general people are adviced to only use copper when you need to and/or make sure you wire correctly the first go.
 
As far as I know there's no need to hold coper at a temp to get good annealing. I've only ever heated it to red then straight out of the fire and let it air cool.

Agree that copper should harden as it is bent. Hardening slowly afterwards makes no sense to me but if you can find some metalurgy that supports the process I'm willing to learn.

I don't find it difficult to apply copper wire because it hardens AS you bend it, not before you bend it. Provided you are careful to only bend where you want the bends, it goes on relatively easy.
I did have one batch that was harder and difficult to apply but that was not annealed - or not annealed properly. Maybe that's what is causing your difficulty with the wire that hardens when you start?
 
Remember to (try to) not bend or straighten it too much before you apply it. Cut the desired length and try not to handle it too much before and during application. Only bend it as you’re applying it, bending only the part of the length of wire that is behind wound on (if that makes sense?).
Unlike aluminum you should avoid straightening or pre-bending copper to fit it into tight spots as much as possible.
 
There are two good reasons for a hold. One is ensuring all of the copper reaches the desired temperature, partly dependent on how you pack the kiln and wire diameter.
The other is that if you hold above the recrystallisation temp, crystals will grow larger. Dislocation of crystals increases hardness. Larger crystals mostly correlate with softer wire, but there are limits.
Making the best, most useful copper wire would take some careful testing, there are no empirical numbers that cover every situation.

FYI, I'm just another amateur who read some stuff, not a metallurgist!

Perhaps the most important thing is how to get rid of the scale (copper oxide) that forms on the surface. Some people quench, others pickle. Whatever you do, dispose of it in a responsible way as its extremely toxic to soil and aquatic life.
 
Annealing is achieved at a little over half the melting point. Melting point of copper is 1357k or 1983f, so if you set your kiln to around 1000f-1200f and give the wire a few minutes to achieve that temp throughout, you’re probably good.

When I used to anneal my own in fire, I went more by color, and there was a point when the wire turned a certain shade of purple, just before becoming red-hot, that I would pull it and quench it.

If it gets hot spots, the wire gets brittle there and breaks. Since you’re talking about relatively thin wire, it’s ok if you under-anneal just a little. 6 gauge will take longer, and I’d do that wire in a separate batch.
 
I've used a propane blacksmith forge to anneal copper. It doesn't matter what heat you use. Just get it red hot [as viewed in a darkened/shady area]and dunk it in water. The shade does make a difference. Doing this in a bright sunlit area the copper likely would melt before it appeared red to your eyes. Rapid cooling in water won't harden the copper as it does not harden the same as carbon steel.
I'd anneal it in straight pieces as uncoiling it does work harden it some.
The old timers used rice straw set ablaze. And some use waste paper for a quick heat. A map gas bottle/ torch will work.
 
I use the lazy method. Get the charcoal grill going and after the burgers cook throw the wire on top of the coals and take it out in the morning. Has worked perfectly every time for me. As always with this type of random “let what happens happen”, ymmv.

image.jpg
 
Brian is correct. I've been working with metals and copper alloys for quite some time, to get copper and its alloys to anneal to a 'dead soft' state, they should be quenched in water. If you don't like scale/oxides on your copper, you can add an acid like vinegar. Jewelers use sulfuric acid or dry 'pH down' pool acid to descale copper and silver alloys. Copper wire is usually fairly pure but develops oxides with high temperatures like most metals so if you want to keep your hands from turning black quench in acid. A super low pH isn't necessary.
 
JeffS73 said:
There are two good reasons for a hold. One is ensuring all of the copper reaches the desired temperature, partly dependent on how you pack the kiln and wire diameter.
The other is that if you hold above the recrystallisation temp, crystals will grow larger. Dislocation of crystals increases hardness. Larger crystals mostly correlate with softer wire, but there are limits.
Making the best, most useful copper wire would take some careful testing, there are no empirical numbers that cover every situation.

FYI, I'm just another amateur who read some stuff, not a metallurgist!

Perhaps the most important thing is how to get rid of the scale (copper oxide) that forms on the surface. Some people quench, others pickle. Whatever you do, dispose of it in a responsible way as its extremely toxic to soil and aquatic life.
Click to expand...
How do you pickle the wire if I can ask?
erich_raudebaugh said:
Brian is correct. I've been working with metals and copper alloys for quite some time, to get copper and its alloys to anneal to a 'dead soft' state, they should be quenched in water. If you don't like scale/oxides on your copper, you can add an acid like vinegar. Jewelers use sulfuric acid or dry 'pH down' pool acid to descale copper and silver alloys. Copper wire is usually fairly pure but develops oxides with high temperatures like most metals so if you want to keep your hands from turning black quench in acid. A super low pH isn't necessary.
Click to expand...
If I am going to quench and want to get rid of scales/oxides, how much vinegar/gallon would add to get that done?
 
I use citric acid, about 100g to 4L, or 4oz to the gallon. Keep an eye on it, Jiggle the wire every so often, 24-48hrs usually looks pretty good. You know the acid is exhausted if a pH strip reads about 7.
 
Last summer, I reannealed some used pieces of larger gauge copper wire (#6?) on the gas grill. I heated it up until the temperature gauge built into the lid said 750° F, but I don't know how accurate that is. I put the wires on the rack and left them until they turned bright red, maybe for 15 minutes or so. I took the pieces out with tongs, dropped them on the patio, and left them until they were cool to the touch. I used them later and they worked fine; holding the branches in position like the first time they were bent.
 
I've done it in a bed of hot coals in the fireplace. Heated it until it uniformly glowed red/orange. Took it out and quenched it in cool water.

Can't emphasize enough not to bed it or mess with it too much. Even dropping it or giving it a jolt can start it to hardening
 
August,
The way that I’ve been enjoying an old grill at 600 degrees and holding that temp for 20 minutes.
Afterword I put it in a bucket for 10 minutes or so to take off the scale.
 
I've annealed a fair amount of construction site castoff wire, mostly in an outdoor fire, pull out when just glowing red, toss in cold water.

Also used a barbecue but it seems a little harder to get it hot enough. didn't turn out as soft as I'm used to.
 
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