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eoteceramics

Slip casting advice needed

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Hi,

I've making these ceramic flowers by slab rolling and hand building the center and hollow underpart.

I need to make quite a few of them and think slip casting might be an option, trouble is I dont know what way

to make a mold of the flower ie what way to place it in the mold, just cant get my head around it. Any help appreciated.

post-13400-135542400208_thumb.jpg

post-13400-135542400208_thumb.jpg

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i'd probably make it a press mold, either as a whole flower or center as a separate component - but whole flower might work just fine since it looks like there's enough draft on the center cone. you may have to reduce the detail on the cone though, then add it back afterward.

 

just make a flower from fresh clay and get it to almost leather hard. then either set it in a base of clay or build one up around it with leather-hard clay slabs. i like to use cut up vinyl/linoleum or tar paper as coddles, but clay slabs work great as well on smaller forms that don't require lots of plaster. then just pour your plaster. pretty simple. slip cast mold will be much more involved and i dunno if this form would really benefit from this unless you make the petals thicker since it may be difficult to get slip into those parts of the mold.

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I make leaves from slabs, pressing the leaf into the slab, cutting it out, and then forming it in a "mold" that I cut from pieces of building insulation. The mold supports the slab while it is firming up; I usually leave them sitting in the mold overnight. The building insulation does not absorb moisture. You could continue making the flower from slabs, place them in a form, and then add the middle parts.

 

I put wood blocks on the corners of the molds; that allows me to stack multiple works and save space.

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Thanks, i have been using fired flowers with no center as a press mold while drying then add hollow underside after. I guess i just wanted to speed it up a bit

by slip casting but maybe Im making more work for myself.Constantly evolving these flowers and finding better ways of making them.

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This is a simple project to do; the flowers are actually shallow bowls. The centers are sprigging. After the casting is released you can alter each finished cast to be unique; also very simple to do.

Slip casting will give a way to replicate the pieces but press molding would be a faster turnaround method. If press molded, a two piece set up would be best, then you can incorporate the coil under the flower or make it separately as sprigging.

 

Be aware of-

-eliminating undercuts when sculpting your original.

-the shrinkage of your finished product.

-if making a two piece press mold, don't forget to make the clay canal on the edge of the working surface of the mold to accept the excess pressed clay.

-Used a good strong properly mixed plaster such as Hydrocal White to make your press molds or use properly mixed Pottery Plaster #1 to make slip casting molds.

-Do not use release soap on your original clay sculpted piece but when making molds use mold soap

only on the surfaces where the plaster surfaces will touch each other or the cottle surface.

-I recommend getting a good mold making book that covers all methods of plaster mold making.

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