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IndustryArena Forum > MetalWorking > Casting Metals > Melting gold flakes. . .?
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  1. #1
    Join Date
    Feb 2007
    Posts
    17

    Melting gold flakes. . .?

    Is it possible to heat up gold flakes so that the melt together? I have a/b a 1/4 oz. worth of gold flakes that I have found in a near by creek. I have had it tested and it is real. I have been told that if I try to melt them that they will evaporate or disappear. Is this true?

  2. #2
    Join Date
    Jun 2005
    Posts
    199

    Melting gold flakes

    No they will not disappear if they are gold. You should use a clean ceramic crucible and a small amount of flux, Maybe borax will do.
    If on the other hand it is fools gold then you should maybe buy some carbon credit to offset the pollution you create.
    WJF
    The More I Learn The Less I Seem To Know

  3. #3
    Join Date
    Jan 2007
    Posts
    634
    Natural gold is usually about 85-92-ish % pure, depending on the area. Impurities are almost always copper and silver, exact ratio also dependent on area.

    Melting them down can be a problem for most people, though, especially in fine flake. It can blow away, burn, combine into organometallics and be lost in the smoke, etc. If you aren't familiar with doing it you probably shouldn't try, especially for the first try. You will most likely lose most of it. If you have to, a properly fluxed ceramic crucible is the way to do it, and use a soft neutral or slightly reducing flame - a large rosebud tip helps for this - and keep it shielded in the flame the whole time unless you want it to turn to a black nasty crust (gold may not oxidize easily, but the copper and silver sure do). Use a preheated graphite rod. Don't use acetylene under any circumstances, but oxy-propane or oxy-hydrogen systems work well. Pour into a pan of cold water with a cotton washcloth at the bottom.

    Why are you interested in melting it down? You can't cast it without a lot of special gear, and if you want to purify it you'd best look to a chemical or electrochemical separation (aqua regia refining, for instance)

    Better yet, talk to a local artisan jeweler - one with their own shop - and they would likely love to help you out with it, likely for free.

    It doesn't take but a minute with the right equipment, too easy to screw up a dozen different ways if you don't. Trust me, been doing work with gold for years now.

  4. #4
    Quote Originally Posted by wjfiles View Post
    No they will not disappear if they are gold. You should use a clean ceramic crucible and a small amount of flux, Maybe borax will do.
    If on the other hand it is fools gold then you should maybe buy some carbon credit to offset the pollution you create.
    WJF
    I think I'm going to like it here... :cheers:
    R&B Cutter Grinding @ www.endmill-sharpening.com!

  5. #5
    Join Date
    Jun 2006
    Posts
    33
    Quote Originally Posted by chroniccodez View Post
    Is it possible to heat up gold flakes so that the melt together? I have a/b a 1/4 oz. worth of gold flakes that I have found in a near by creek. I have had it tested and it is real. I have been told that if I try to melt them that they will evaporate or disappear. Is this true?
    Hi...No it will not evaporate. There are jewelry supply stores in most cities. There ask them for a 1 x 3 x 6 inch charcoal block.

    Carve out a small depression with a spoon or something. Pour the gold dust into the depression and cover with Borax or flux that can be also purchased at the supply house.

    Then with a torch, and no it really does not matter the type or gas mixture...and yes I am a goldsmith on the side...get the torch flame going softly at first and began heating everything...the flux will melt and capture the dust...

    Then increase the size of the flame and keep it on the pile of dust until it begans fusing...it will take several minutes, and use a sizable torch tip, as it takes a lot of heat...

    Regards,

    Preston

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