[Jewelry making - Article 00019] - Re: [Orchid] Steam de-waxer

[James Binnion]

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    Steam de-waxing works great! I started doing steam de-waxing in a
    big enameled pot on a hot plate with flasks held above the water on a
    wire mesh. When I went to work for a commercial caster we decided to
    steam de-wax to lessen the amount of burning wax fumes being vented
    in to the air as we were doing 20-40 4x9 flasks every evening and
    generating lots of smoke and fumes. 

    We found that the parts that were cast from steam de-waxed flasks
    would sometimes exhibit rough surfaces and even spalling of the
    investment. The problems were mostly located in the areas farthest
    from the sprue opening up at the top of the tree and were most
    common on flat thin parts but it did happen on other parts as well
    but always near the top of the tree. The theory we developed was that
    the wax in the tops of the flask was melting before the sprue rod had
    melted. The pressure from the expansion of the molten wax in the
    pattern was breaking down the investment as it could not escape down
    the sprue or into the investment because the investment was
    saturated with water from the steam. We found that we could eliminate
    the problem by either slowing down the rate of temperature rise in
    the steamer or keeping the temperature at about 180F in the steam
    chamber. Either way the main sprue had time to melt out and relieve
    the pressure on the cavities in the flask before the investment was
    damaged. 

    While I never saw this in my small studio casting flasks done in a
    pot on a hot plate it was a problem in the larger flasks at the
    casting shop. This may be due to the much higher power that the
    commercial steam de-waxer had and the more rapid temperature rise or
    it could be just the larger flask size. Either way if you find your
    steam de-waxed flasks having poor surface quality slow down the rate
    of rise or run the de-waxer at a lower temperature. 

Jim

James Binnion
jbin AT mokume-gane.com
James Binnion Metal Arts
http://www.mokume-gane.com
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