[Jewelry making - Article 00424] - Re: [Orchid] 18k white gold casting problems

[T R. Hawkinson, Ltd.]

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    Dear Brenda, Here are a few thoughts: 

    1. I don't think you are melting the allow hot enough. I've know
    other casters who have had the same problem. I don't think you are
    melting the deox off the metal. Are you using deox 18k? If you are
    not using deox your temperature is fine. I melt at 1950 degrees F.
    This clears off the deox and gives me good castings. I haven't cast
    18 karat in a while, but would not change anything. 

    2. I cast as cold as possible. I know this may sound nuts, but you
    set up the same ring in about four flasks. Now cast each flask colder
    and colder until one does not fill. Add 100 degrees and you have the
    correct temperature for your flask. This may be a little tricky. A
    lot depends upon your casting machine. 

    3. I gave up trying to cast white gold by vacuum. I think you get
    much better results using spin casting with those colder flask
    temperatures. When you pour the metal you give it too much time
    between the melt and the flask. It may seem like a little time, but
    compare it to spinning pouring is too long a time. If you can spin
    those problem ones you may also have your problem go away. 

    4. With vacuum casting the investment shouldn't be the problem. Does
    your machine pull a good vacuum? If so, the investment probably isn't
    the problem. 

    5. If your change anything don't make a LOT of changes. It's hard to
    pin point what you know are doing right. It sounds like you know what
    you are doing. 

    6. The refinery may also be using a different blend of deox in the
    alloy for 18k. If you are using deox you may try going back to the
    old standard alloy mix. Have them chop up some sheet 18k white gold.
    This gold is usually free of any deox material. If you use the
    standard alloy without deox what you are doing sound like it would
    work. So by getting the alloy without the deox you may NOT have to
    change anything. 

    7. Spin casting wait ten minutes to quench. Vacuum casting wait
    fifteen to twenty minutes to quench. 

    Good Luck and Best Regards, 

Todd Hawkinson
TR the Teacher
T.R.Hawkinson, Ltd.

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