How to Cast a Head: Stage 1

I cast my puppet parts in several stages.  The first stage is to create a latex shell, which makes a kind of skin for the puppet.  I like liquid latex because it’s great at maintaining all the details in the mold, and it doesn’t shrink.  For the head it’s essential because it will eventually hold the hair in place — I actually jab hair in by the strand, and the latex is sticky enough to make each strand stay put.

The down side of latex is it doesn’t hold its shape at all.  I’ve tried stuffing the latex skins with cotton batting, wire armature mesh, and other materials… even lining the inside of the latex skin with layers of stretchy latex-soaked gauze as it’s drying.  But as soon as I go through the “hair-jabbing” process, the head loses its shape.  Soooo… after much experimentation, I found a compound urethane modeling foam that fills it just perfectly.  (I’ll do tutorials on the foam filling and hair jabbing stages later.)

(One side note about the plaster mold:  I brush it with a couple coats of mold release before I do anything with it, just in case any of the foam eventually leaks out, even though it’s generally not necessary with latex.  Latex doesn’t stick to plaster, while urethane sticks to everything.)

First, I use a crummy paintbrush to fill in the eyelids and the details around the eyes.  The eyeballs are going to be glass beads, articulable in a latex socket.  So this stage allows me to get into the part around the eyeball, before I put the eyeball in place in the mold.  (The mold itself has wires that hold the glass beads in position… more on this in my later moldmaking tutorials.)

Once the latex eyelids are painted in, while the latex is still wet, I stick the placeholder eyeballs (just plain unpainted glass beads, that are the same as the ones I’ll eventually use for the final puppet) in position on the wires.  Then I fill the holes of the beads with plasticine.  This just ensures that the latex doesn’t go into the holes… since I want the eyeballs to eventually move around in their sockets, I don’t want latex to lock them in place, which is what would happen if latex seeped into the beads.
head innards

The next step is to paint the inner eye sockets with latex.  This is what’s pictured above — I’ve done 3 fairly thick coats of latex, letting it dry in between coats.  I also brush a coat or two of latex in the nose, mouth, and around the face… just to make sure it all gets coated well.

Then I make a simple armature for the head.  This is one straight loop of 1/16th inch aluminum armature wire, twisted together at the ends.  I like to wrap a bit of plumber’s epoxy putty around the loop part, keeping the head more solid for when I eventually handle the finished puppet.  I’m especially concerned about the hair-jabbing process… this tends to change the shape of the head.  So with this putty, it’ll hold its proportions.

Here’s where the armature sits in the mold… there’s a groove in the plaster made just for its little tail, and it’s held in place by that blue fun-tack stuff, which happens to be the ultimate secret weapon for stop mo animators.  (I wish there was a friendlier term for the secret weapon…  maybe it should be called a secret cookie:  something that’s sweet, simple, and makes life easier.)

Next, the cast is assembled and wrapped in those wide elastic bands that hold stems of broccoli together, and a bright yellow strap I got at Active Surplus.

That’s not really hummus.  Here’s where I pour some water into some liquid latex, making enough of the mixture to fill the head.  I add JUST enough water to make it more easily pourable… the liquid latex, when taken straight out of the jar, is quite thick.  I don’t have a specific formula for this; basically I add about a teaspoon of water at a time until the mixture seems runny enough to drip into the mold.  Too much water and the latex skin won’t be very strong — like most things, it’s a fine balance.

Mix thoroughly.  A good way to describe the consistency is that it should look like pancake batter.  If it’s overmixed and gets too many air bubbles, just let it sit for a while (with the lid on the container) so the bubbles have time to dissipate.  Otherwise the bubbles will be embedded in the skin.

Then I fill the mold to the top and let it sit for 15 minutes or so.  By filling it to the top, I’ll know that every part of the mold is covered.  You could put a little in and swish it around, but this technique seems to work better.  I don’t remember why it should sit for 15 minutes — I think I read that somewhere.  Anyway, it doesn’t hurt.

Then I pour the excess latex back into the hummus container from where it came.  This mixture is definitely reusable.  Don’t pour it back into the original jar of latex though — keep a separate container for the pre-mixed watered-down stuff.

Then the head gets to sit for a couple of days to dry.  To speed this up a little, I sometimes use this hair dryer contraption I made… it’s basically a hair dryer taped to a cardboard tube taped to a strip of that rubber (or is it plastic?) tubing that is used to coat electrical wires (one of those Active Surplus things.)  The dryer is set on its lowest, coolest setting… just to get some airflow into the mold, without burning down the studio.

A word of caution, echoed from some highly disappointing moments:  BE PATIENT.  Do NOT open the mold too early.  Actually, don’t open the mold at all, until the next stage (foam filling) is complete.  If you go on to the next stage before the latex is totally dry, the head will get mangled by the pressure of the urethane as it foams up.  If you open the head to check whether it’s dry or not, you won’t be able to get the mold back together with the skin in tact, because it’s impossible to reset the eyes back in place on the wires.  So your head will be ruined.

It sucks to have to go back to the beginning and start all over again — let the latex skin sit for 3 or 4 days if you want to be sure it’s totally dry.  2 days should be OK if you’re using the hairdryer trick.  To be precise, I found it safe to go on to the next stage after 2 days and 6 hours, with the hairdryer on for a few hours a day.  The electricity bill was pretty high doing this…  I do feel bad about using so much electricity, though there was some AC usage in the studio too to compound it.  I would feel worse if we weren’t using Bullfrog… but that’s another story.

The next stage:  filling the head with urethane foam…

6 thoughts on “How to Cast a Head: Stage 1

  1. Pingback: How to Cast a Head: Stage 2 | windowboxes

  2. Pingback: How to Cast a Head: Pre-Stage 1: The Eyes | windowboxes

  3. Pingback: How to Cast a Head: Pre-Stage 1: The Eyes - stephanie dudley

  4. Pingback: How to Cast a Head: Stage 2 - stephanie dudley

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