Molds – Hole Versus No Hole

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    I’m researching the purchase of a couple of ceramic molds for slumping/draping. One of the online vendors says when placing an order to tell him whether you “want holes drilled in the bottom or not.” What does he mean? What is the difference? When do you use a mold with a hole versus one that does not have a hole? As you can tell – this is new for me… Haven’t used any molds as yet…

    Thanks for your help!



    The holes are there to allow air to escape preventing large air bubbles from forming under the piece. I would suggest letting them drill the holes for you. All molds I have purchased have the holes pre drilled. The holes sometime become clogged by kiln wash. Use a small nail or piece of wire to keep the holes cleaned. Hope this helps.


    You never need holes in a draping mold.  You often, but not always, need holes in slumping molds.

    Holes allow air, that would otherwise be trapped, to escape from between the glass and the mold. That air expands during the firing and makes it more difficult for the glass to drop.

    Very shallow molds usually do not require holes.

    If you have a choice, take the holes.  They won’t hurt anything even if they end up being unnecessary.

    Helios Kiln Glass Studio


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