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Make a mold for intricate vase before bisque firing?

itsN4dz

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Jul 23, 2025
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So my sister and I just finished an intricate 12" tall low-fire clay vase. She's really worried about it surviving the bisque firing since it's got delicate details and some protruding parts, and that took a very long time to work on. I've tried reassuring her with all the usual precautions, like slow drying, candling, a super slow ramp-up, and silica sand on the kiln shelf. I also mentioned we could use Bisque Fix if it breaks during bisque, or kintsugi if it cracks after glazing. She still said she doesn't want to risk it and she's set on making a mold of it.

We both don't have extensive experience in making a mold so I'm worried about damaging the clay, losing fine details, plus the cost and time involved. Would a release agent impact the clay's drying, firing, or glazes? Is molding a leather-hard piece before bisque firing a sensible precaution, or is it just unnecessary stress given the other steps we're taking? Hopefully someone can give us advice on the next best steps to take!
 
Making a mold from leather-hard clay can preserve the design but adds risk if the piece isn't uniformly hydrated or sturdy enough to handle pressing or casting pressure. Most release agents like soft soap or sodium silicate won't interfere with firing if applied lightly and rinsed afterward, but they can affect surface texture if overused. Can you confirm if the protruding areas are undercuts or if they'd allow for a 1pc press mold rather than a multi-part slip mold?
 
Working with clay before it's fired can be a bit risky since it's fragile and drying can be tricky. Your precautions seem good, so trust what you're doing. If you're still concerned, take some pictures and be extra careful when firing. Just so you know, making molds is usually riskier than the actual firing.
 
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