Sunday 6 February 2011

Hands Part 2

 After finishing the sculpt of the Mail Mans hands I put them into the freezer to harden them up ready for the moulding process. I will be making a two part Polyurethane mould.
The first step was to build up a wall of clay that covered the sculpt half way up. The hardness of the frozen hands meant i didn't nick or damage the sculpt as I was applying the terracotta clay.

Next I added Plasticine keys to help the two halves slot together. I used foam board to construct a box around the mould. I sprayed the whole surface will wax so that the two sides would release easily.

Above is a picture of the mould box filled with PU resin. This is the first half of the mould done.
After the resin was dry removed it from the box, flipped it, and removed the terracotta clay leaving the hands still in the mould. After adding more Plasticine keys to the resin surface, and building a new box, I poured the second half of the mould.

Finally here are the two completed mould halves cleaned out and ready to be used. The hand armature fits into the negative space and is held in the mould by the K&S slot. The next stage will be casting the hands in skin tone silicone.

5 comments:

  1. exactly what PU resin are you using to make the molds and where can i purchase it? Also, how do you remove the terracotta clay without removing the hands which are also made of clay?

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  2. Igot the PU resin from the link below.

    http://www.tiranti.co.uk/subdivision_product_list.asp?Content=Biresin+G26+Urethane+Resin+-+Polyurethane+Resin+-+Casting&Subcategory=60&Subdivision=228

    The terracotta clay peels away from the plasticine hands because the two clays don't realy tend to fuse tegether. Also the plasticine should be held very securly in the first half of PU resin. Its always a good a idea to take your time so as not to disturb the plasticine sculpt.

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  3. Is that the same type of resin you use for making the face replacements and the head?

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  4. Can most resins be used for both mold making and for casting finished pieces like the puppet head?

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  5. Hi James. Yes, I used the same resin for casting and mouding. Its sometimes called 'Fast Cast Resin'.
    Your second question is a bit difficult to answer. It really depends on the properties of the resin and what you use it for.
    I like to use fast cast (PU) for the puppets head because its lightweight, and very strong. You probably could use another kind of resin, like polyester, but it would be heavier and more brittle.
    Another alternate material for mould making is plaster of paris.

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