Casting the jawbone raised a host of issues that I didn’t realise would be a problem, but hopefully it will work out in the end. Before we could make a hot rubber mould of the jawbone Becky (the technician) and I decided to make a plaster cast of the jaw, as we felt it would be too fragile to make a hot rubber mould from directly.
- Before we could begin casting I had to fill in the holes in the jaw (where the rest of the teeth originally were) with soft wax, so that it would be easier to cast. I also used a little superglue to secure the two teeth- we were worried that they may have come out of the jaw when we de-moulded it, so this was a preventative measure.
- I then pressed the jaw carefully into some clay and built up clay walls around it, and then applied a few layers of vegetable oil to the jaw to help release it from the mould once the alginate had set
- I mixed up a small amount of quick set alginate which I poured into the clay mould and left to set
- Once this had set I carefully removed the clay and rinsed the jaw and alginate, before greasing it up with more oil, and building up clay walls around it
- Another batch of quick set alginate was then poured over this, and left to set
- The clay was then removed, and the two halves of the mould separated and the jaw carefully removed.
- After cleaning both halves of the mould I fit them together and secured them with elastic bands, and was then ready to pour fine casting plaster into it
- The first attempt didn’t work very well and only the thickest section of the jaw came out, so for the second attempt after pouring in the plaster I moved the mould around to encourage the plaster to flow through the whole mould
- Once I opened the mould up I realised one half had not worked out, and the other half, where all the detail was, was too thin- to fix this I cut up scrim and layered that and some more plaster on top of it until it was thicker and stronger
- I then de-moulded it and created a hot rubber mould from that plaster cast. Because the detail was lost on one side I decided to make a flat mould, rather than a round one that needed to be cut open, to save materials
- The final photo on the slideshow is of the original jaw, first failed plaster cast, second plaster cast, and de-moulded wax cast of the jaw- as you can see there are a lot of details that need to be worked back into the wax by hand, but I am confident that it is doable