[Jewelry making - Article 00821] - Re: [Orchid] Casting problem - course grainy surface

[John A. Henkel]

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    Hello Richard, Lee covered the health and mixture of the investment.
    I can think of some other possible problems. Your burnout schedule
    looks fine as long as you are holding the 200, 500, and 700 (F) where
    damage can be done if hurried through. With too high of a climb rate,
    steam can build up enough pressure inside the flask to produce
    similar symtoms. Was the flask bench hardened for an hour before the
    burnout? 1350 should be the top of the burnout. Investment can break
    down with temperatures higher than that causing the same symtoms.
    When is the last time you calibrated your kiln? The needle (or LED)
    can read "1350" but can actually be much hotter. Another possibility
    is air pockets in the wax near the surface that explode and fill with
    investment during vacuuming. This occurs most often on one of a kind
    waxes that have been carved, added to and recarved. It's always the
    details isn't it ?! 

John, J.A.Henkel Co., Inc., Moldmaking Casting Finishing,
Producing Solutions For Jewelry Artists


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