Mold Making Workshop with Pangea, January 25, 2003

 

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This first row of pictures is the 2 part plaster mold.

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Building the clay mound Ready to pour the first half Ready to pour the first half Ready to pour the second half The finished mold

To make a two part mold:
First, build a platform out of clay to put the original object on.  Then build up the clay around the object, so that there is an even layer, parallel to the table.  This layer needs to be at the widest point in the pot, or what ever you are molding.  Otherwise the piece will never come out of the mold.  Put a few "keys" on the  clay mound.  these will guide you in putting the two halves of the mold together.  In the case of the round green vase, there are 2 round keys, and one raised trapezoidal one. the trapezoid is great because I can see it from the side of the mold when the mold is together.  

You have to plan where the opening (gate) will be for the mold.  I chose the top of the green vase, Pangaea chose the top of the lemon (where the stem would be).  

Then make a wall of clay around the mold.  The wall will hold in the plaster.  If you make it smooth, the plaster will be nice and smooth too.  I did this by rolling out a slab of clay for the wall.

Next SPRAY THE MOLD AND ORIGINAL MODEL WITH MOLD RELEASE.  Other wise you may never get the plaster off of your original.  Next pour the plaster in.  (I sprayed mold release before mixing the plaster.)

When the plaster has setup, remove all the clay, but keep the original model in the plaster mold.  Build a wall around the plaster mold, spray with mold release, and pour the 2nd half of the mold.

 

These are misc pictures from the day

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Poured molds.

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Product for flexible mold

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building the 2 part mold

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open face mold, and the model

The Open faced mold (last picture in the row) is a lot easier than the two part mold.  Just put the item on a slab of clay.  Fill in any under cuts.  Build a wall around the slab, and SPRAY THE CLAY AND THE MODEL WITH MOLD RELEASE, and then pour in the plaster.  These molds are great for pressing clay into, or paper or anything that works one sided.
These are the steps to making the flexible polyurethane mold.

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