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Thread: melting copper

  1. #1

    melting copper

    I have been casting for a few months now, and still having trouble melting copper. I have a long thread started in the casting section titled Delf Clay. I have worked out most of my problems, but still can't seem to melt a few ounces of copper reliably. It just seems to melt into a blob, and then stays that way. My last attempt I tried for about 1.5 hours but was ultimately a failure. So, I ask you, is the anatomy of my foundry the problem, or am I being too impatient? Or could it be something completely different? Sorry if this seems to be a repost of the same questions I asked in previous threads, I just want to get to the bottom of this. attached are pics of my foundry. You'll see it has an open face, which I suspect is the cause of my problems, but I'm no expert. Clicking the link will take you to my facebook group where I've been posting pics of my work. There is also a short video of my foundry in action.
    Thanks, JD

    https://www.facebook.com/marc.malavo...8538477761755/

  2. #2
    No can see. No bookface for me. Never had it, never will. Can ya stick it on youtube?
    Visit me: WWW.HandcraftedLanterns.com
    "Sometimes by losing a battle you find a new way to win the war"
    -- Donald Trump --

  3. #3
    I don't have a youtube account, but will set one up asap. For now though, here is a still pic. marc's iphone 2016 342.jpg
    Attached Images Attached Images

  4. #4
    Are you firing that with the huge gaping hole in the front? Try tightening up your setup. Looks like you are not getting hot enough. You'll need to hit 2k degrees. Copper melts at 1984F.
    Usually requires some forced air to reach those temps on propane unless you can control the heat loss in your furnace.

    Another option, got an oxy/acetylene torch? You can melt that in an open crucible outside with no furnace.
    Visit me: WWW.HandcraftedLanterns.com
    "Sometimes by losing a battle you find a new way to win the war"
    -- Donald Trump --

  5. #5
    I can only just reach copper pouring temp with a reil style burner and an enclosed furnace but it takes about an hour to get there and the melt can freeze before i've finished pouring if i'm too slow.

    I'm using a 4kg crucible and pre heating everything, i normally do an alloy melt then two or three brass before even trying the copper.

    It is my favourite though, something about the glow of molten copper seems just right.

  6. #6
    Member
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    Apr 2016
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    Adelaide Sth Australia
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    A closed furnace is definately needed to get the temperature up to melt copper.

  7. #7
    yes, I'm firing with the front open... It seems to work on very small quantities, under 3OZ approximately. I figured I need to close it up, but just wanted to eliminate the possibility that I am just being impatient. I actually resigned myself to the fact that I simply just could not melt copper, which is ok for the most part, since the jewelry I make would be kind of heavy in copper. However, I might just try drilling through a fire brick and trying one more time...

    I have a B tank and an oxi/air torch, but it's a small tip, and it doesn't seem to work much better, plus I have to hold it the entire time.

    - - - Updated - - -

    Thanks Watermark, good intel.

  8. #8
    Administrator Site Admin
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    Huatulco, Mexico
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    Even when you have enough heat to melt copper, which you may or may not have now, you will find it a difficult metal. It oxidizes badly, and more than likely you end up with a crucible mostly of dross.

    When I switched from using leaded tin bronze to using Everdur, years ago, in my foundry, I had to alloy my own. Everdur is not commercially available down here. I use copper wire, silicon, and manganese. I melted the copper and got mostly dross. I finally got enough copper melted that I could add some silicon and manganese. Then it calmed right down and melted beautifully. Ever since then, to alloy more Everdur, I always start with one third of a crucible of Everdur and then when I add the copper wire I push it under the surface of the molten Everdur to prevent it from coming in contact with oxygen.

    Most people who melt copper commercially (so I hear) use induction furnaces in which they have control over the furnace atmosphere.

    Richard
    When I die, Heaven can wait—I want to go to McMaster-Carr.

  9. #9
    All my copper scrap is cleaned and flattened pipe.

    I was told that some wire has a protective lacquer coating, similar to alloy cans that creates a lot of dross.

  10. #10
    Senior Member
    Join Date
    Jan 2012
    Location
    Buffalo, NY
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    2,507
    It's only my method, but I assume that any wire associated with magnets and is wound, where I can see the copper color, is going to be lacquered. But if it has regular insulation on it then it will be unlacquered. I doubt that's a universal fact, but that's how I sort it. I don't know if the coils can be cooked and washed to get rid of the lacquer to be useful for melting or not. But if one decides to cut the wire out of a transformer or motor give it a scrape first to make sure it isn't aluminum. I strip anything larger than Romex. I have a stripper that works pretty good. Anything smaller goes into the pile awaiting the day scrap is valuable again.

    Pete

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