[Jewelry making - Article 00413] - [Orchid] 18k white gold casting problems

[david]

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    Dear All, In the last year we have begun to experience some
    difficulties casting our 18k white gold projects. We had not
    intentionally changed anything when the problems began, and I'm
    wondering if anyone has any ideas or thoughts. Our castings in this
    alloy are turning out with a very heavy orange peel texture. Thin
    sections are not affected as badly as thick, heavy sections.  Our
    casting scenario is as follows: 

    Alloy: 18k white gold from Hoover and Strong. 

    Casting technique: Deep well vacuum casting 

    Metal melting technique: We use a Kerr Auto Electro melt for melting
    the metal 

    Pour temperatuRe: We have varied from our standard temp for this
    alloy of 1870 degrees down to 1840 degrees with no discernable
    difference. 

    Flask temp: 910 degrees 

    Quenching: We have varied from waiting just until all color is gone
    from the button down to almost cold, with no discernable difference. 

    Investment: Kerr Satin Cast 

    These are the specifications we have used for casting this alloy for
    many years with consistently good results, and so we suspect that
    there is an outside change we are not aware of. We are not
    experiencing any difficulties with our yellow gold castings or even
    our 14k white gold castings. These alloys cast at a lower
    temperature, so we are wondering if the higher temperature is
    reacting unfavorably in some manner. The only things we can think of
    to explain the problem are changes in alloy, changes in the
    investment, or problems with the accuracy of our instrumentation. I
    have contacted Hoover and Strong to see if there were any changes in
    their alloy, but they assure me that is not the case. They recommend
    we switch to their 18k palladium alloy; we are not keen to do this
    if we can correct whatever is causing our current problem, as we
    like the color and working properties of our current alloy.  Hoover
    and Strong said it sounds like the metal and /or flask is too hot. 
    They said they would get back to us on the lowest recommended temp
    but we haven't heard yet and I will admit I'm a bit antsy; we have
    all of these 18k white gold custom designs coming due..... 

    As you see we are puzzled. Does anyone recognize this problem?  Does
    anyone else regularly use this product, and if so, can you tell us
    the lowest temp we can cast at and still get complete castings? 

    Also- I remember some time ago reading posts about an unannounced
    change in Kerr's satin cast investment. Is there any truth to this
    and if so, what types of troubles did it cause other people? Maybe
    our orange peel texture is related? We have not contacted Kerr, but
    perhaps we should. 

Thank you all.
Brenda
david lee jeweler
Mason City, Iowa


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