After sculpting an oil based clay design, the product then needs to be moulded so that casting the appliance can be done a number of times to maintain more than one prosthetic piece. This is done using a two part moulding process to create the positive mould, which in this case will be the shape of the models face, and the negative which will be what has been sculpted. Below is a step by step for moulding part two with process images for the specified brief:
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| Image one |
What you will need:
- Cloak
- Clay
- Oven
- Oven
- Mod rock
- Cold water
- Plaster
- Gloves (latex free)
- Burlap
- IPA
- Scissors
- IPA
- Scissors
- Screw driver
- Sculpting tools
- Large paint brush
- Mould release spray
Step 1: Set up equipment and put on cloak. Turn the oven on to 50 degrees.
Step 2: Heat the clay in the oven until it is soft then add a thin layer to the cast which has not been sculpted on. Smooth the clay down. This is called an overflow and is made to catch excess latex when squeezing the positive and negative mould together.
Step 3: Use a sculpting tool to create a thin line between the sculpt and the rest of the clay. This line should allow you to see the cast and is called a cutting edge. The clay around the cutting edge should be extremely thin as this will be the edge of the prosthetic piece and will need to blend well onto the skin. Then build a clay wall an inch high around the mould using water based clay. (Image two). Spray the mould with mould release spray which will help the two moulds release when pulled apart.
Step 4: Using cold water, soak and drain pieces of mod rock and add this around the outside of the clay wall. This is to secure the wall.
Step 5: Using scissors, cut squares of burlap to fit over and around the sculpt in preparation of using it.
Step 6: Mix plaster to cold water at a ration of 2.5:1 creating a paste like substance. Use a large paint brush to add the plaster to the sculpt slowly building it up. Also add the burlap during this process (Image three). This is done so that when the plaster is dry and the negative is pulled from the positive, the negative stays firm and does not crack.
Step 7: Once all the plaster has been added and begins to thicken, leave the product around 20 minutes to cool down before separating the negative and the positive.
Step 8: When the plaster has cooled, use a screw driver to release the negative away from the positive. This must not be rushed and must be done with care other wise there may be a chance of the plaster cracking. (Image four).
Step 9: Once the two parts have separated, the negative mould should resemble the sculpture. (Image one). Remove the clay from the negative mould to be left with a mould of the models face.
Step 10: Clean the two moulds using cold water and IPA. This is done to remove all the clay. You should then be left with a two part mould ready to cast the appliance.
- Sculpting tools
- Large paint brush
- Mould release spray
Step 1: Set up equipment and put on cloak. Turn the oven on to 50 degrees.
Step 2: Heat the clay in the oven until it is soft then add a thin layer to the cast which has not been sculpted on. Smooth the clay down. This is called an overflow and is made to catch excess latex when squeezing the positive and negative mould together.
Step 3: Use a sculpting tool to create a thin line between the sculpt and the rest of the clay. This line should allow you to see the cast and is called a cutting edge. The clay around the cutting edge should be extremely thin as this will be the edge of the prosthetic piece and will need to blend well onto the skin. Then build a clay wall an inch high around the mould using water based clay. (Image two). Spray the mould with mould release spray which will help the two moulds release when pulled apart.
 |
| Image two |
Step 4: Using cold water, soak and drain pieces of mod rock and add this around the outside of the clay wall. This is to secure the wall.
Step 5: Using scissors, cut squares of burlap to fit over and around the sculpt in preparation of using it.
Step 6: Mix plaster to cold water at a ration of 2.5:1 creating a paste like substance. Use a large paint brush to add the plaster to the sculpt slowly building it up. Also add the burlap during this process (Image three). This is done so that when the plaster is dry and the negative is pulled from the positive, the negative stays firm and does not crack.
Step 7: Once all the plaster has been added and begins to thicken, leave the product around 20 minutes to cool down before separating the negative and the positive.
Step 8: When the plaster has cooled, use a screw driver to release the negative away from the positive. This must not be rushed and must be done with care other wise there may be a chance of the plaster cracking. (Image four).
 |
| Image three |
Step 10: Clean the two moulds using cold water and IPA. This is done to remove all the clay. You should then be left with a two part mould ready to cast the appliance.
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| Image four |
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