A chronicle of the meanderings, false starts (which in retrospect, while sort of embarrassing turned out to be highly instructive), epiphanies, selective apathy (still evolving), wild mood swings, opinions (subject to frequent change), and life lessons of an inveterate dabbler (and her latest dabblings).

Saturday, March 24, 2012

Annealing Copper (or Silver) Without a Torch

I was responding to a comment from Sandra on my "Power of Money" post, and a thought occurred to me: Do you really need a torch if you're only annealing metal, and not intending to melt it? If not, what kind of heat source would someone already have in her home that she could use to soften  metal? Well, duh, I thought, how about a gas or electric range?

Electric Range in "Goldenrod" ca. 1975
The melting point of copper is 1982.21°F, or 1083.45° C. (Sterling silver is 893°C). Gases used in torches, such as butane, propane, MAPP and acetyline produce flames with significantly higher temperatures than this, which can melt copper (although because of the heat dissipation qualities of metal, and other factors, butane is not very effective, because the flame often isn't hot enough to overcome the dissipation--I've never been able to melt copper with a butane torch. I've also not been able to melt heavy gauge copper (like 16 gauge wire) with propane, which is why I switched to MAPP). Silver is much easier to melt, as the melting point is a little lower. You can melt smaller gauges of silver wire with a butane torch (I didn't have any luck with gauges heavier than 22 though using butane. I kind of think butane is a joke unless you're lighting a cigar. In which case I'll be in the other room with the window open.)

The element on an electric stove, set on high, is somewhere in the neighborhood of 550°C. A Bunsen burner produces a flame of about 1570°C. Natural gas, typically used in gas stoves in the United States, is about 1950°C on room air. (The effective temps of these flames apparently can be lower than this in real-life situations--flame temperatures quoted in data sheets and such refer to "perfect" conditions where no heat loss due to environmental factors is assumed.) Lightning, by contrast is 30,000°C. You should stay away from lightning.

I myself have an electric range (pictured above). I thought I would see what the element set on high would do to a 22 gauge copper disc.

I placed my copper disc on the cold burner,


cranked up the burner to high and let the disc sit there for a while. I dunno, 10 minutes?
It turned a little reddish. Another larger disc I did before was glowing dark orange, maybe I left it on there longer? Or maybe the other disc was a thinner gauge.

I let the burner cool down and removed the disc with my tongs. I ran it under cold water to make sure it was cool enough to handle. You will have sooty fire scale on it which will need to be removed with a pickling solution. You can use a mixture of household white vinegar and salt for that--just pour some vinegar into a little cup, just enough to cover your metal, put about a 1/2 teaspoon of salt in there, toss your metal in, swirl it around a bit and let it sit for 15-20 minutes. Then rinse it off and rub some baking soda on it to neutralize it, and scrub with steel wool. Should be good to go then. (The salt is important, the vinegar alone doesn't seem to do the job.) No pickle pot needed for this procedure! This is low tech stuff for us working poor.

The heating from the electric element did indeed soften the copper. Not as much as with a torch where you get it glowing bright orange, but I could bend the disc with my fingers whereas before I could not. It took the texture from my half crown coin easier than non-annealed metal. (See top photo). Obviously, this will work for wire too. Many intricate wire projects are much easier to do with annealed wire. (I have tried annealing nickel with my MAPP torch, to no effect. It did not noticeably soften it. Annealing red brass, which I prefer to yellow brass, produces a pink discoloration, from drawing the copper content to the surface, which I have never successfully been able to remove, even with commercial pickle, so I don't recommend annealing either of these metals.)

You should be able to get it even softer if you have a gas range, as the flame is much hotter than an electric element. You should be able to get it glowing orange. (Always be careful with flame and heat--even metal that doesn't look hot may still be very hot and burn you.) You will need some long steel, insulated tongs or pliers for that, something with a good gripping tip so you don't drop your metal, and insulated because the heat will travel to the handle and possibly burn you.


You might even be able to make a sterling silver headpin in your gas stove flame, although it would be challenging because the flames are oriented vertically. If you try it, you'll know what I'm talking about. If anybody has ever tried that, tell us about it!

So you see, all you torch virgins out there, you can still anneal your metal to an extent for stamping and texturing, even if you don't yet have a torch. Or even a gas stove.

21 comments:

  1. Ohhhh what about the barbie??? I bet all sortsd of things could be cooked out there and it get pretty damn hot! Genius you are!

    ReplyDelete
  2. Thank you Thank you!!! Perfect information I've been looking for! :)

    ReplyDelete
  3. I have a glass top stove... think I would be tempted to use a cast iron frying pan on it to hold my 'metal' would help keep a coil of wire under control too!

    ReplyDelete
  4. Oh wow, I ask one innocent question and a whole new blog post pops up! Awesome. I'll try this out as soon as I get my hands on some sheet metal. I do indeed own a gas range, and shall report back on my experiments once I get around to play with fire. This will no doubt own me even more frowns from my roomie ... *laughs*

    Also, great tip about the home made pickling solution, thank you! <3

    ReplyDelete
  5. You trail blazer you!!!! Love the recipe for the pickling solution, too! I really do love how you will try just about anything and share your findings! Thanks!

    ReplyDelete
  6. awesome idea--You are brilliant!

    ReplyDelete
  7. Before I bought my butane torch, I would ball head pins on my propane stove. (That's an awkward sentence, wha'?) I've successfully melted up to 18g sterling and 20g copper. Was successful with 18g copper once or twice but it requires a steady hand and getting it in the hottest part of the flame very accurately. The torch won't melt 18g copper at all. I still use the stove to anneal long pieces of copper wire. It's so much faster. Oh, and whether I'm using the stove or the torch, the big range hood is always on.

    ReplyDelete
  8. Perfect, I have a butane torch, I like the color of old metal
    Some metals will grow old on the gas stove.
    For the pickling vinegar as well, also use lemon juice and salt.
    I posted in my blog as I grow metals.
    You're always a genius and I like to read you.
    a kiss.
    Cinzia

    ReplyDelete
  9. I laughed at your funny banter AND I learned something....does life get better? Thank you so much for this post~

    ReplyDelete
  10. Do you anneal your metal wire before you make things eg the bangle/bracelets that used such heavy wire? I have always been very impressed with how you manage these heavy wires.

    ReplyDelete
  11. Not sure my 1958 GE gets has hot as the goldenrod, but I'll give it a try. I have a big butane torch I use for art clay that will anneal metal. I too have never gotten nickel silver to do much. Not sure what that would take. Thanks for the post.

    ReplyDelete
  12. haha, 1958 GE! love it! Penny, I never did anneal any of the heavy gauge wire for my bangles (I was usually making them in the car on my lunch hour and that is one place I have decided not to use my torch.) I should have annealed the copper! I used 12 gauge wire, plus I hammered it, so it took some real elbow grease to make some of the loops, esp. the nickel and brass. But it CAN be done! I have an iron grip.

    ReplyDelete
  13. What a thought provoking post. Now, all I have to do is remember where I read it when I am next confronted by the fact that I have no torch to heat anything.

    Thanks.

    ReplyDelete
  14. I kinda like how red brass looks bright pink after annealing--but to get brass back to looking like itself, try this: soak in pickle to remove the fire scale; then, soak in a solution of 3 parts white vinegar & 2 parts hydrogen peroxide,in a plastic or glass container (not metal!!),about 10 minutes, till the pink is gone. Rinse in water. The solution will turn blue. Not harmful to you or the environment. So, fire away!

    ReplyDelete
  15. Thanks Jill! I've tried that pickle recipe before on copper. Took the black sooty stuff right off, but it seemed like the dark pink remained. I'll try it again on brass!

    ReplyDelete
    Replies
    1. I dunno--I like pink. Copper enjoys remaining very pink if you quench it in water when it's blazing red hot. Try letting the metal cool a bit, or alot, before a cool bath if you're going for true copper. A pickle dunk removes the black gunk!

      Delete
  16. I use gas stove flame :)
    ciao dall'Italia

    ReplyDelete
  17. Thanks so much for all that info. You've convinced me that if I'm going to play with fire, I may as well go for the torch!

    ReplyDelete
  18. I had the same thought a while back,(I don't have a torch yet.)and used my gas stove to anneal some copper. It worked great. Thanks for the pickle recipe, too.

    ReplyDelete
  19. Just what I needed to know, since I have yet to purchase a torch. Awesome!!! Gracias.

    ReplyDelete