[Jewelry making - Article 00374] - Re: [Orchid] Article: Minimal Metalsmithing

[James Binnion]

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>     Fired and fully sintered metal clay, is fine silver or 22K gold and
>     may be filed, cut, hammered, dropped, scratched, annealed, forged,
>     bent, you name it, add infinitum. 

    What is so wonderful about metal working and what PMC lacks is
    metals amazing ductility and malleability. 

    When you can take a 5 mm thick slab of PMC punch a ring out of that
    slab with a finger size of 6, 2mm wide and fire it then stretch it
    up to a size 11 and back down to a size 7 without annealing or
    breaking it then I will believe you that fired PMC has the same
    properties as wrought fine silver. PMC is porous as are all powdered
    metal products without the use of special processes to close up the
    pores. And pores make it weak. 

    There is a company that makes seamless wedding rings from powdered
    metals. They need to be easily resizeable by the jewelers who sell
    them. To make them they press the metal powder with 40 tons per
    square inch to achieve 80% of theoretical density pre firing. Then
    the preforms are placed in a high vacuum to remove water and other
    contaminates before firing then fired in a controlled reducing
    atmosphere. At this point they are at 95% of theoretical density.
    They are pressed again and re fired to further close any pores.
    After that final firing they achieve 99% of theoretical density which
    is similar to a well cast item. They can then pass the above test.
    There is no way PMC comes near that in density, ductility or
    maleability. 

Jim

James Binnion
jbin AT mokume-gane.com
James Binnion Metal Arts
http://www.mokume-gane.com
360-756-6550
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