I'm making a silicone cast using an internal armature to manipulate the eye and jaw expressions, similar to what was illustrated in StopmoNick's video here:
There's no dialogue, but there are several expressions, so the camera would need to see the teeth in all positions. From the "Ooh" expression where you can't see them at all, to having them gnashed and baring.
But I have no idea how to incorporate this. Should I sculpt the teeth into the original sculpt? If I do this, the character would look like he was baring his teeth the whole time, right? Would I just have to animate it with clay?
If you need to bare the teeth, and also cover them, you need the teeth to be attached to the skull and lower jaw, so they don't move when the lips change expression. That means the lips cast are fairly thin with the wire inside, so there would be a big mould piece inside the mouth. Then you would probably attach gums and teeth after the puppet is cast.
It is not easy to get much expression with mouths, especially the Ooh sound. I set up a bunch of wires to do it on a robot head but there was no silicone covering it so the wires were free to move a lot. (That was the only reason I included a bit of Werewolves of London in the audio clips, I wanted to do the Ahh-Ooh sounds. Otherwise the sounds had something to do with robots or giant heads and made some sense.) https://www.youtube.com/watch?v=R77aVipcDt8
In a smaller puppet you might be able to have a single wire in each lip, but zig-zagged, so it can stretch out and compress in a bit.
I did manage a sort of Ooh sound with monkeys, cast in foam latex, because the mouths did arch out a bit more compared to humans. But I couldn't stretch the lips forward in a small circle, I had to press the sides of the mouth together and just shape the middle as an Ooh. Someone has posted it, not authorised but a clean copy: https://www.youtube.com/watch?v=aF_NFNx5LHQ
Ron Cole managed a greater range of expression for his In The Fall of Gravity short, but the puppets were large, with heads close to the size you would need to put a hand inside. He had lots of cables moving toggles, and could animate with a lot of precision. The other people to really go into expressions for silicone puppets were McKinnon Saunders for Corpse Bride, who used tiny gear mechanisms inside the heads.
Clay animation can do any shapes you want, and replacement animation can do it with a more finished look. Laika has gone with 3d printed replacement animation to get the full range of expressions - well beyond the range of any actual creature in fact.
I would try this,,sculpt the lips is the ooh position and articulate the corners of the mouth back hopefully making the mouth look neutral
I was going to go with replacement faces at first, minus the 3d printing, but since there was no dialogue, I thought it would just be easier to manipulate wires in a skeleton. I probably will end up going with the wire inside the lip, but still am not entirely sure how to cast/mold that.
do you have a picture of your sculpture so far?
Getting a wire embedded in silicone requires you to coat the inside of the mould with a skin of silicone, then coat the wire (covered in physio wrap) with silicone, then place the armature into the mould and pour another mix of silicone in to fill the gaps. The first coating of silicone will have solidified before doing the second. This way you do not get the wire coming through to the surface.
But it is tricky placing the armature so the wire is in the right place, not too far from the end and not too close. One way to achieve this can be to glue the wire into the head armature only once it has been positioned in the mould. It will of course depend on how accessible it all is!