The procedure is quite simple, actually. First, you create a head using oil based clay. Next, you create a plaster mold. The mold is filled with liquid latex and then emptied again, so the inside is covered by a thin skin of latex. This is repeated several times until the skin is thick enough. It is then removed from the mold and painted. This is, in fact, the same method that's also used to create latex masks!
Here's what you need:
- Oil-based clay (for the model)
- Water-based clay (for the dividing wall)
- Plaster
- Vaseline
- Liquid latex
- Sculpting tools
So first I had to make a head. I don't have much experience in sculpting, so I didn't really expect it to be perfect. But a shrunken head will probably look deformed and twisted anyway, so it's not really a problem! The core of the head is a ball of crumpled paper and aluminium foil, around wich I made a head. I did this to save clay, because I would need a lot of it to create the mold and I wasn't sure I had enough.
Creating a face wasn't easy. I kept a reference picture at hand, and had to restart several times (especially the nose and ears were difficult), but I managed to create something more or less decent. I made some holes around the eyes and lips, because they are supposed to be sewn shut. I also made a large cut in the back. Real shrunken heads were made by removing the skull, and the head would have to be cut open to do that. One thing it doesn't have is skin texture. This is a bit beyond my skills at the moment, and I was happy enough to be able to create an actual face.
Next up, I made a two part plaster mold of the head. I practiced a bit with easier shapes first, because my first attempt at making a mold of a head failed miserably. First of all, it was full of bubbles, and second, the plaster didn't harden properly. Perhaps the fact that it had been sitting in an open bag in my basement for the past three years had something to do with it... I picked up a new bag of plaster at the hardware store, and that worked much better.
Here's how it works. First, you have to divide the object you want to make a mold of in two using water based clay, creating a dividing wall. The reason you use water based clay is that it doesn't stick to the oil based clay, so it's easy to remove later. I made a wall around the head, a few centimeters wide, and made some small holes in it. This will make it much easier to align the two parts of the mold afterwards. The dividing wall is rubbed with vaseline so it won't stick to the plaster (no need to do this with the oil based clay, plaster won't stick to that anyway).
The next step is messy! I highly recommend mixing only small batches of plaster, because it hardens fast! In my case, it stayed liquid for about ten minutes. After that, it's still possible to apply it with a spatula, but five minutes later it was too hard to work with. The mold is built up in layers. The first layer is the most critical, because this has to get into all little details. Once that's done, additional layers are added for strength.
For the first layer, the plaster has to be liquid enough, so I used a bit more water. The plaster was the consistency of cream, wich is ideal. Using an old paintbrush, I put the plaster on the face, making sure I didn't miss any spots. Even with the extra water, the mixture started hardening quite fast. I mixed another batch of very liquid plaster and applied a second layer. After that, a nice thick layer of plaster to strengthen the mold. You'll notice the plaster will start to get warm at this point. That's the chemical reaction between the water and the plaster. It will feel solid, but in fact it's still very fragile; it will take about 24 hours to harden fully. While it was hardening, I put some moist paper towels on the dividing wall, so the clay wouldn't dry too much.
After 24 hours, I removed the dividing wall, making sure I didn't damage the head underneath. It should come off easily. Rub vaseline on the plaster, so the second half of the mold won't stick to the first one, and repeat the process.
Another 24 hours later, you can open the mold and remove the clay. This can be a bit tricky, make sure not to rush things or you might damage the mold! Start by prying the two halves apart with a screwdriver. Apply some force at various points around the seam, until it opens. Then, you can take it apart and remove the clay.
Now you have a two part plaster mold of your original clay model. The next step is casting latex! It will take a few days before it's finished, so be patient. I started by applying a generous layer of vaseline on the seam. This will seal it and make sure the latex won't flow between it too much. I put the two mold halves together and secured them in place. Some people use rubber bands for this, I used duct tape!
Put the mold upside down, and fill it with liquid latex. Next, pour it back in the bottle. A thin layer of latex will coat the mold and form a skin. Put the mold straight up over some sort of container, so the excess latex can drip out. This is very important! If you don't, the skin won't have an even thickness. When it has dried enough, you can turn the mold upside down so it can continue to dry fully. The latex is completely dry when it turns translucent. I applied four layers of latex this way, always making sure it had dried completely before the next layer. Took me about a week.
After all that waiting, it's finally time to remove the shrunken head from the mold! Again, be patient, don't rush things, don't ruin it, yadayadayada, you'll probably be used to it right now. The latex skin should come out pretty easily. I didn't use any release agent at all, and I could peel it out just fine. The only parts that were a bit trickier were the ears and nose, but I managed to get them out without damaging anything.
There will probably be a line of 'flashing' around the head, where some latex got into the seam. This is easily removed with a razor sharp knife. Here's the result:
In the next tutorial I will talk about painting, adding hair and finishing touches.
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