Post #373919 by Babalu on Tue, Apr 15, 2008 6:16 PM

Hello All,

Both Bowana and myself have had several folks ask us if we could share a little of what we know on how to build plaster molds for slip casting ceramics. We talked about it, and would love to share some pointers. There are a few few other threads on TC that talk about how to build plaster molds, but I guess one more isn't going to hurt anything. I personally have been playing in water based clays for many years now, but I had no hands on experience with plaster mold making until Bowana did a demo over at my house during one of our "Chop" events.

I did take several pictures of the demo that Bowana and I did for this Chop event which should work as good aid in explaining the processes. It may take several days to get all this information posted on this thread, but I think it will be fun for you, if you find this type of topic of interest.

Well, to start off, a good thing to talk about might be what type of materials can one make a plaster mold from? The answer is basically anything...fired ceramic, wood, plastic, found objects...as I said, most anything, and/or a combination of materials. In this demo I choose to do my cast master form out of an oil based clay called "Plasticine, or Plastilina". This type of clay does not need a mold release agent (mold soap) added to the outside of it in order to pull away from the master mold as the oil in the clay won't stick to the plaster. Plus, one can get some really fine detail in the plastilina, and not have to worry about the clay drying out on you like you would with water based clays. Also, as Bowana put it "this is the way the pros do it" :)

For the master sculpt, I used a 2" diameter PVC pipe as a core material and added the oil based clay to it. This had a few advantages for me...1. I did not have to use so much clay...2. It gave me a nice round shape and predetermined height in and armature to add the clay to. Pictured below are some of the tools that I choose to use when sculpting in the plastilina. "Roma" brand plastilina is a fine choice when choosing a brand of clay to sculpt with. Number 2 Roma is a little softer and has been used mostly for sculpting busts. Number 3 Roma was a little harder and my personal favorive to work with. Number 4 Roma is harder yet...some people like this feel. Please see picture below...Bowana, can you show some of those cool tools you use to work in Plasticine? Please correct me Bowana if you notice me missing steps, or anything elase as we move forward.

[ Edited by: Babalu 2008-05-04 12:22 ]

[ Edited by: Babalu 2008-05-04 20:43 ]

[ Edited by: Babalu 2008-05-05 20:43 ]