[Jewelry making - Article 00593] - [Orchid] Sterling silver melting & pouring

[Marco Roncaglia]

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Hello to everyone.

    I need some information about sterling silver melting and pouring in
    an investment casting process (gypsum moulds), in order to cast
    rings. 

    I've been using aluminium alloys for industrial purposes and now I
    have to cast sterling silver. I'm completely new in this field. I
    made a couple of trials with this procedure, as first approach: 

    - a button and a central sprue (10 mm x 3 mm diameter) for each ring
    (2 cylinders). 

    - SiC crucible, electric oven 

    - metal pouring at 980 C in a vacuum machine 

    - mold temperature 500 C 

    I noticed a considerable amount of shrinkage: castings showed a
    partial filling, due to an incorrect solidification (I obtained only
    the lower part of the rings, those connected to the sprue). I think
    I'm not accostumed to work with this material and I obviously made a
    mistake (or more...). 

Any suggestion is welcome.
Thank you very much.

Marco

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