Ceramics Hump Mold Use TIP

Ceramics
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During the process of monitoring the In-Progress shelf, this item was found.

mold crack
mold crack1511×1330 197 KB

I thought I would drop a note for the new ceramics makers of why this happened.

When you use a mold for your project and drape your clay over the mold (hump), you generally leave it on for about 1-2 hours. This allows you to time to put a foot on your project and/or decorate the exterior. You want it on just long enough for it to retain the shape of the mold, when you remove the clay.

If you keep your clay on the mold, the clay shrinks as it dries and will crack like this piece.

Hope this helps.

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I’m guessing the time you can leave it on the mold is proportional to the thickness of the clay. I’ve had much thinner pieces crack faster than an hour.

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Yes John, you are correct.

There are many variables that can affect how quickly the clay dries. This would include the thickness of clay (as you mentioned), temperature of space, humidity, etc. I wanted to give a general guideline, but thank you for pointing out that some pieces may dry more quickly.

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