1) Clean the mould out with IPA so that no bits of clay or dirt remain as these will get stuck in the cap plastic.
2) Rub Vaseline into the mould and massage it in. Then stipple the excess off.
3) Mix cap plastic with IPA or any 99% alcohol. Needs to be a thin syrupy texture.
4) Pour some cap plastic mixture into the mould, spread around with a brush or stick then pour off the excess. Dry with heat or naturally until cap plastic has completely dried. Repeat this 2 or 3 times.
5) The place where the prosthetic goes determines how soft it needs to be. The more the piece needs to move the more softner needs to be added. The more softner that's added the more soft and fleshy the piece will feel.
- If you want the silicone to be 100% softened use the same amount of softner as silicone type A and type B combined.
- If you want the silicone to be 200% softened need to use two times the amount of A and B combined.
Attempt One
For this I wanted to try making my piece 200% softened so I used 20 grams of A, 20 grams of B and 80 grams of softner ( A + B x 2 = 200% C )
6) Use three sticks each lettered A. B and C at the top and with a black dot at the bottom.
7) Put a tiny amount of pigment onto the stick and mix well into the silicone. Hold the stick up and look how quickly the black dot on the bottom appears - around ten seconds gives a convincing transparency of flesh.
8) Use red flocking to add a more realistic quality to the silicone when it sets. Can add it in when all three silicones are mixed.
9) Mix all three silicones together, making sure they are thoroughly combined.
10) Pour a thin stream of the combined mixture into the flashing, then into the wounds.
11) Scrape the excess silicone off using a stick or metal scraper. Scrape one way and then the other making sure to get off any silicone that isn't in the sculpts.
12) Leave the silicone to dry sightly then put another 2 layers of cap plastic mixture of the top.
13) Leave to dry and set completely on a flat surface.
14) Lift one edge slightly and begin to powder underneath the piece. Continue to pull back and powder until the piece comes off.
Evaluation:
As can be seen from the photos above my first attempt at casting went very wrong. I don't know whether the mixture was too softened or whether it just wasn't mixed well enough but the silicone never set properly meaning it was too soft and leaved out of the cap plastic in some areas. Even if it hadn't leaked the piece would have been too squidgy to apply to the skin well, meaning it wouldn't last well when put on the skin. However I was happy with the final colouring of the piece and the thickness of the cap plastic. On my next attempt I will use a less softner in the silicone mix and make sure I mix the the silicones together a lot more.
Attempt 2
This time I tried making my piece 150% softened. I used 20 grams of A, 20 grams of B and 60 grams of C ( A + B x 1.5 = 150% C )
Evaluation
I was a lot more pleased with with my second attempt at casting and this flat piece will be usable this time. I used the same technique as last time but just a different percentage of softner. The pieces feel soft enough to sit on the skin well enough and to move with the skin but they hold there shape and haven't leaked this time. I also think the colour and cap plastic is good. The only problem with this is the slight holes that can be seen in the photos above. These formed because the cap plastic mixture was too thick meaning it bubbled as it dried. These are mostly on the flashing which isn't a problem as this won't be glued to the skin however there are a few holes on the eyebag meaning it won't be perfect when it's glued on the skin however as it's meant to be a very old eyebag the holes could be passed off as deep pores. Altogether I'm very happy with this cast and am looking forward to sticking it on the skin and colouring it to see how it finally turns out.
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