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Why did this happen? There is a perfect storm of factors. Draining, during slip casting, creates suction and slip is heavy (1.8 times heavier than water). And this mold is tall with a narrow neck. So that creates a lot of suction. A slip having inadequate fluidity complicates draining. This round shape, even with printing artifacts, also releases well. How can this issue be avoided?
-Draining the mold carefully, holding it near horizontal for much of the drain.
-Use a well-deflocculated slip.
-Add bentonite to the slip, perhaps 0.5%, to make it stickier and slow down release time (which also slows down the casting time).
-At times, this will happen despite all efforts. In that case, if might be necessary to use a tube (e.g. 1/2 or 5/16”) to pump most of the liquid slip out of the bottle before inverting it. Adapt a 3D printed pour spout to keep the tube centered, at least near the mouth of the bottle.
| Glossary |
Slip Casting
A method of forming ceramics. A deflocculated (low water content) slurry is poured into absorbent plaster molds. As it sits in the mold, usually 10+ minutes, a layer builds against the mold walls. When thick enough the mold is drained. |
| Projects |
Beer Bottle Master Mold via 3D Printing
A project that took several years of failures and blind allies and is finally coming together - so much simpler than expected! |
| Troubles |
Casting Slip Problems
Casting slips are deflocculated in order to reduce water content. It is important to understand this phenomenon and know how to assess a slurry to know what it needs. |
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