So yesterday I started again with the Alice mould, I was going to make it with plaster but my lecturer, Dave, thought it would work better using RTV silicone, it also meant it was another model making material I can say i've experimented with.
It's pretty scary stuff, the catalyst is pretty poisonous, so you have to be super careful with getting it on your hands and touching food etc.
It's made with 1 part catalyst for every 20 parts silicone. We mixed it a cup at a time, using two cup-fulls to create a bed in the bottom of the mould. I hadn't mixed the second cup thoroughly enough so the bits from the bottom of the cup were still a bit sticky when the rest of the mould was set, so it had to be left over night...
The Silicone and catalyst were weighed on digital scales to ensure we used the right amounts...
Once poured into the mould box the silicone levels itself out really well, unlike the vinamold! Air bubbles rise to the surface and pop, but I helped speed that along by popping them with a craft knife....
Having left the base layer to set fully over night, today we continued with creating the bottom half of the mould, it took a lot more silicone this time. First we poured in a layer of silicone to lie the model in, then once it had settled in, poured another cup of silicone in, close to the model, allowing it to level itself out, then any bubbles were popped with a craft knife again...
We added a third cup of silicone, bringing the surface level up to the halfway point along the side of the model. In order to make sure the two parts of the mould line up we pushed pencils into the wet silicone, these were pushed through some foam board to hold them in place whilst the silicone sets. The ends were sprayed with a release agent to ensure that the two parts of the mold will come apart and wont be held together by the pencils....
Hopefully tomorrow the silicone will be set. The next stage will be to use PVA to coat the surface of the silicone and once that has dried the next layer of silicone can be added to create the second part of the mould... though it has just occurred to me that Dave is otherwise engaged tomorrow and I don't know where the silicone is. eeek. so hopefully i'll manage to find it!
With any luck i'll manage to track it down and finish the mould, then on monday, having let it set over the weekend, the model can be removed, the plasticine stripped off, and the armature placed back in the mould which will then be filled with silicone. fingers crossed!
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