Stalker Puppet

Stop-motion puppet I made as part of my uni course at UH. Design based on a stalker from Mortal Engines by Philip Reeve which everyone should read. He's 1:6 scale and is made from silicone with a wire armature and polyurethane fast-cast additions.

I started out by doing some concept drawings for the design. He needed to look futuristic, but also that he'd been through the wars and had had various parts replaced/repaired. This is the design that I went with, though it was subject to heavy change while I was sculpting. His torso armour was quite heavily Turian inspired as I'd just finished Mass Effect...

I started out with a basic wire armature and built up a very basic body form with plasteline to work onto. Plasteline is oil based and can be smoothed down with lighter fluid. It gets softer while warmer and harder when colder, so when working fine detail into the sculpt one may want to put it in the fridge.

The large blocks of armour were built up first so that I could check I was happy with the overall design. I also went back and added in a support to the internal armature so I could sculpt without having to hold him.

Once I was happy with the basic form I went in and added detail, such as the steps just under the knees, on the feet and lower legs.

I went back into the armature for the left hand and added thin wire to support a sculpt of the fingers, as at this scale it was difficult for plasteline to hold its own weight. The fingers on this hand were going to be fully animatable, so had to be individually sculpted.

I continued adding details and altering the design until I was happy with the combination of details. Once I was content I added battle damage to his armour, and cut two small pieces of green acrylic for the eye lenses. What follows are pictures of the final sculpt.

Now that he was fully sculpted, it was on to the moulding stage. As I was going to be casting him in a soft material I needed to mould him in a hard material - for this I used a very fine hard plaster. This meant the mould had to have two parts so I embedded him in soft clay, made a wall using foam board and pushed in a few holes to create keys.

I mixed up a small amount of plaster and splashed it over the sculpt by hand, blowing through a straw onto the sculpt to make sure the plaster had gotten right into all the detail. Once this layer had started to go cheesy I mixed up more plaster and poured it over the sculpt, making sure there was a good thick layer over all of it. Once the plaster had started to cure I scooped some of it up and piled it slightly over where I knew the body was thickest, making sure it would be strong enough in the important areas. I could have used more plaster, but I wanted to limit the resources I used as much as possible.

Once the plaster had cured I removed the foam board wall and the clay that the sculpt was embedded in, taking care not to damage the sculpt. Any clay left on the sculpt I could remove with water and a soft brush - plasteline is oil based so there was no risk of damaging any detail.

Once happy that all the clay was removed I rebuilt the foam board wall and added a layer of slurry to the plaster mould so the second half of the mould would release from the first. I also added a couple of channels with clay for excess silicone to run out of, as I was going to be press-casting this piece. At the bottom of the feet you can see channels in case I wanted to pour this cast if the push-cast didn't work out.

I repeated the earlier step of moulding before letting it all dry overnight. In the morning I opened up the mould and had to be quite brutal in removing my sculpt from the mould. They rarely survive the moulding process, but it's never that much fun to destroy a sculpt you've been working on for the last few weeks/months. Unless you're so totally sick of looking at it that you really want to just rip it apart...

For the wire armature inside the silicone cast I twisted two lengths of aluminium wire together using a drill and a desk clamp. Bend the wire in half, put one end into the drill and clamp the other end tightly. On a fairly low speed spin the drill and the wire should twist into a beautiful double helix. Wire which has been treated this way is much stronger and can last much longer than a single strand of wire. Also it gives something for the silicone to key into, ensuring that the silicone doesn't delaminate from the armature.

To make the armature only bend at joints I cut lengths of plastic pipe and slid them over the wire before securing them with Milliput.

The armature for the hand used a blob of Milliput securing five pieces of cotton-thread-coated wire which would bond much better to the very thin fingers of the model than just naked wire would.

Both halves of the mould were given a very thin coat of vaseline to help release the cast before a skin of silicone was painted in. I sat by the mould constantly readjusting the silicone until it had set to the point where it would no longer run. I did this first with the fleshy silicone for the areas skin would be visible, left it overnight to set, trimmed any excess and then did the same with the opaque silicone used for the rest of the cast.

I then positioned the armature inside one half of the mould and poured silicone into that half. I had to weigh down the armature because the foam I'd used to bulk up the body kept wanting to rise to the surface.

Once that silicone had set I again trimmed the excess, then poured silicone into the second half of the mould. I then clamped the first half to the second half while the silicone was still liquid and let it set overnight.

And this was what I pulled out of the mould! The flashing around the cast was removed with a pair of very sharp scissors

Mucking around with stop-mo puppets is fun. However, as this was my first time working with silicone this puppet has two problems; I cast him using a moulding silicone which made him a lot stiffer than he should have been, which limited his range of movement quite significantly. There is also no way to secure him to a base - stop-mo puppets have some way of fixing them in place, often with a nut embedded in the foot which is used to fix the puppet in place with the use of a hole in the set and a corresponding bolt, which is the method I would use with this puppet. Both these problems are with the cast, so could be fixed by casting him another time.

Painting silicone is tricky. You need to use a mix of white spirit, clear silicone sealant and oil based paint in thin washes to colour properly. The piping in his arm joints is on its way to being black in this next picture, but it takes time.

I had very little time before the deadline to paint him, so I went with a pretty monotone colour scheme which makes it look like his armour is ceramic. I'd like to cast him again and paint him all crazy looking at some point, but no time soon. The extra little bits of armour he has in the finished pictures were sculpted in plasteline, moulded in silicone and cast in polyurethane fast-cast and then stuck on with a silicone glue. These are parts which wouldn't have been practical to cast as part of the main body, so were added afterwards and painted to look the same.


Robert Torres said...

Great work man!

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