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Can You Pour Slip Into Things Other Than Plaster Molds?


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#1 missholly

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Posted 10 February 2011 - 10:43 PM

im looking at plastic and/or silicone molds made for candy or soap making.
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#2 bciskepottery

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Posted 11 February 2011 - 09:15 PM

Give it a try. You'll likely need some type of release agent, such as Murphy's Soap, WD-40, etc. Also, avoid forms with undercuts that will prevent the slip from releasing. Will likely take some time to dry; that is the beauty of plaster -- it absorbs the moisture from the slip and helps it set up.

#3 Seasoned Warrior

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Posted 12 February 2011 - 12:32 AM

im looking at plastic and/or silicone molds made for candy or soap making.


The reason plaster is used is because it absorbs the moisture from the interface between the plaster and the clay forming a skin, depending on the time the slip is left in the mold determines the thickness of the finished item. when the time has elapsed you pour out the slip and let the form set firming up more. You have a somewhat similar situation with bisque since the bisqued clay will absorb the moisture form the contact zone between the slip and the mold. With plastic you don't have the same situation, so I am not sure how you will have a usable piece from a mold that does not absorb moisture. I've used molds for chocolates as a press mold to make sprigs but doubt plastic and latex would be a satisfactory mold material for clay. Latex or plastic will work for plaster items but plaster hardens through an exothermic chemical reaction and the action is completely different. You can certainly try it but how long do you want to wait to get a form and then it will probably be solid since the moisture will be removed only in the area in contact with the air. I strongly believe it will not be a satisfactory situation. Now if you use the plastic or latex mold to make a plaster object you can make a ceramic mold from the plaster object. I think you would be a lot happier with that approach.

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Charles

#4 selim

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Posted 11 January 2012 - 11:50 AM

I make little pieces,thus do not have drying problem.So I tried silicone molds and not satisfied.Whatever I do I couldn't prevent air bubbles.

#5 Dinah

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Posted 12 January 2012 - 08:56 PM

Hi Miss Holly, If you found/made molds made from paper pulp, that would work. Absorbs the moisture. Also a bit OT but in the same vein, I've used newsprint to pour slip/majolica colors onto newsprint, and then pressed the dry-ish slip (watch it like a hawk for when the water bloom just goes off) the surface onto leatherhard surface and/or onto majolica glazed work. Tricksy, and I found the Jackson Pollock motifs were just a bit too random for me. I can see cutting, trimming and being a bit more deliberate with this method could be a way forward. Color choices for slip need to be well thought out. Not just an easy-peasey filler activity for a wet Sunday afternoon. ;)
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