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Thread: Flashing, I think, in a sterling cast

  1. #1
    Join Date
    Aug 2022
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    9

    Default Flashing, I think, in a sterling cast

    Hi think it's called flashing. What I'm getting is the filling-in of detail and thin slivers of silver in areas. The pendant I'm trying is a celtic design and I've found that in between the detail it gets either filled with silver or there is this thin sliver of silver.
    It seems that some detail is being lost in the mold.
    Can anyone help with what is causing this?

  2. #2
    Join Date
    Dec 2009
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    Central London
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    Flash is what you get when two halves of a mould dont fit together accurately, or closely enough.

    You haven't told us what kind of casing is involved. Dennis.

  3. #3
    Join Date
    Mar 2011
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    Manchester UK
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    If its lost wax casting it can be caused by incorrect investment mixture it has too much water in it

  4. #4
    Join Date
    Aug 2022
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    9

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    Thanks for your replies and sorry for the lack of info.

    I'm using plasticast, a perforated flask, cast in a vacuum system. Distilled water, 24-26 C. Mixed as recommended. The flask sat for about an hour before being placed inside a plastic bag with some water in it and left overnight. It's a 4 " dia flask. I assume that's considered a small flask.

    The burnout goes up to 780 and is held for 6 hours. That's what the resin maker suggested. It's Jamghe resin.

    Maybe flashing isn't the correct term. I'm wondering if I have cracks inside the mould that the metal is going into. Also, I just tried another cast and it also is bad. Looks like porosity and the fine detail is filled with metal in areas. But a piece next to it has nice clean detail.

    I'm not experienced with this so I'm at a loss at the moment what to try next.

    Click image for larger version. 

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  5. #5
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    Aug 2022
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    Sorry, forgot to mention the silver casting temp is 990 C and the flask temp is 590 C. Metal melted in a furnace and graphite crucible. Vacuum cast as mentioned before.

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