Somewhat ineptly, I completely failed to take any photos of the casting process. Nevertheless, I'll try to describe it, though as mentioned in an earlier post, when it came to applying the latex I followed Lars Carlsson's superbly informative video pretty much slavishly.
First, make the skin, for which you will need liquid latex. To make painting the head easier later on, it's best to tint the latex first to provide a base colour. For this, use special latex colourants (I get mine from another London store, 4D Modelshop - £2.20 for 150g). White, a smidge of brown, a hint of red, and a dab of yellow, together with a tincture of blue, muck around until you find a colour you like. I haven't yet tried their recipes, but this is an excellent looking guide to how to achieve various flesh tones, from pale & interesting (okay, pasty) to dark as dark. When you're happy with the colour, add a little to the latex - the latex should be very pale, it darkens as it dries. Experiment first.
I made the actual skin by pouring a little of the tinted latex into one half of the mould and dabbing it around with some sponge. Build up a few layers, adding each as the preceding one dries. Strengthen the mouth area with pieces of bandage soaked into the latex. Also, it would probably be useful to add a smallish 'plate' made from a semi-flexible material (perhaps thin styrene sheet) to the lower inside of the mouth because that is where only a thumb acts upon the mouth, and the small surface area of the thumb will push through the flexible foam and rubber. The upper part of the mouth doesn't need it as the other four fingers will manipulate it.
You want both halves of the mould to have a few layex layers built up so that the colouring is fairly opaque. To create cavities for the eyes, I used the same hemispherical shapes that the final eyes will be made from and actually glued them to the inside of the latex skin exactly where the final eyeballs will need to go. Then clamp both halves of the mould together with the bungee ropes, seal around the edges outside with platicine, and pour some more latex inside and tilt the mould around to get the latex to fill the seam between the two halves. When you're satisfied with this, leave for a few hours to dry.
What I'm trying to get is a flexible foam puppet head with a cavity for my hand to go up it to manipulate the mouth. Ideally, I should have made a special core for the mould, but I couldn't be arsed. Instead, when the mould was ready with the dry latex skin coating the inside, I propped up the mould topsy turvey so the opening was at the top. I then put on a marigold washing-up glove and stuck my hand inside the mould, holding the inside of what would become the open mouth. Then I poured in the urethane flexible foam mix.
This stuff is magic! For this head I used Tiranti's Self Skinning Flexible Polyurethane Foam. Although self-skinning, the process to get it to skin is slightly more complex and is something I shall experiment with later. Suffice to say that for this puppet, I needed the latex skin.
So anyway, I poured it in around my marigold-glove-clad arm and held that arm dead still for fifteen minutes or so as the foam rose and set. It gets quite warm, but not dangerously so (though it may be hazardous without the protection of the rubber glove). When set, the glove is firmly embedded (it's the yellow thing poking out from underneath the neck) and you can slip your hand in and out. The fit was very tight, caused by the foam compressing the flesh of my hand and forearm as it expanded and cured. If using this technique again, I would wear a glove over that hand and then the rubber marigold glove on top of that, to form a slightly larger cavity. Once the foam was fully cured, which you can tell as the surface ceases to be tacky, I then removed the casting from the mould.
Then clean up the copious flashing on the seams, cut the eyelids open with a scalpel and remove the plastic hemispheres, and get painting the hair...
I used standard Liquitex Artists' Acrylics for the hair - it's surprisingly flexible and sticks well. Later, I will subtly colour the skin using similar paints in much the same way I coloured the static Stephen Fry sculpture. The eyes were made using the same technique as for the Patrick Moore eyes.
So, it's not yet finished, but here are some photos of it thus far:
Most of the skin colour is the base tinted latex, but some areas have already had some painting - the rubber of the neck was very thin causing the white foam to show through, so I painted that; I had painted eyebrows on but they were rubbish, so I've painted over them, and some other areas where the skin was too thin and the foam was showing had a similar treatment to the neck.
Also, the ear on the right was completely deformed due to some balls-up with the mould (I suspect that a pry-hole was too close to the ear so that when I shoved a screwdriver in to help prise the mould apart, the pressure of the screwdriver distorted the plaster). So I ended up sculpting a new ear, making a small plaster mould and casting a tinted latex skin. I then stripped part of the skin from the bust's distorted ear and glued the new skin on, a disturbingly quasi-surgical procedure... If you look carefully at the ear on the right (above), you can see where the new skin doesn't line up with the old; it will be patched up with latex at some point.
I'll be replacing the irises of the eyes with larger ones later, when I can get a friend to print out a sheet. I'll probably add veins to the eye on the left to give it a slightly bloodshot look (the eye on the right is, on Nick Griffin, in real life a false eye).