[Jewelry making - Article 00849] - Re: [Orchid] Red gold alloy - Double Metal Casting

[Dreamgate9]

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    Will, If you want to cast with another metal or object already in
    place (imbedded in the wax), two rules have to be observed. The
    first is, obviously, that the object imbedded has to have a higher
    melting point than the metal poured around it. Imbedding platinum or
    steel, for example will work in a gold or silver casting. Imbedding
    gold into a platinum casting will not work. 

    The second rule is that when the wax melts, the object imbedded has
    to be held in place by the investment or in will simply drop to the
    bottom of the cavity. 

    Let's say that you want to imbed a platinum sphere into an 18k gold
    cast disk. If the sphere is large enough to protrude through both
    sides of the wax, the investment will hold it in place when the wax
    melts. If it does not protrude through the wax, simply adding a
    platinum wire to the sphere will hold the sphere in place by
    projecting into the investment. The wire can go through the wax and
    project into the back side of the casting, or it can project out the
    front. Having it go through the wax will often anchor the sphere
    into the cast metal. Having it project out the front will allow the
    sphere to rotate once the gold is cast, since the two metals will
    not melt into each other. This would give you a "ball and socket"
    joint. 

    If David wanted to cast two red gold saddles onto the shank of a
    platinum ring, just wrapping the wax around the platinum shank will
    not create the strongest bond. I would cut some locks into the
    platinum shank, either with a drill or burr, and make sure that the
    wax flowed into these cavities. Since the ring shank is so large,
    the investment will easily grip it. Sprue the wax as you would
    normally. When you break out the casting, you will find the red gold
    has cast around the platinum and is held in place by the mechanical
    connection of the locks. If you want a seamless connection, you will
    probably have to add solder to the joint. And, since platinum does
    not oxidize when heated, the pre-polished platinum ring needs only
    the finish on the red gold to be complete. 

    One of the most basic projects you can do with this technique is to
    simply put platinum wires into a wax ring, with metal sticking right
    through the wax. Cast this in gold, or silver, and you will get a
    casting with platinum wires sticking out of it like a porcupine.
    Just file the wires smooth to the cast surface, and you have
    platinum inlay! With a little practice, you can get quite
    creative... 

Doug Zaruba


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