Milquetoast Process: Behind the Scenes Satori 1, MAKING A HUMANOID...
This post will discuss the process of creating a custom silicone prosthetic mask (part two here). In our case it was to create the featureless appearance of The Humanoid for our upcoming sci-fi short film, Satori.
the semi-finished Humanoid mask.
There are several steps to this process, so this post will only cover our initial mold making process.
Some places online will recommend using a polystyrene (styrofoam) head as a foundation for the mold making (as seen here). While this may not be a bad idea in most cases we knew our design would probably already make breathing more difficult. We instead opted for an exact fit by doing a life cast of our actor.
PREAMBLE
When doing life casts of the head or face the subject will not be able to speak, so make sure they have another way to communicate. We used thumbs up as "yes," or "I'm ok," and a flat handed palm tapping on the knee for "no," or "everything is not ok."
Here we go...
Supplies:
- 2lbs alginate
- 5lbs plaster bandage
- 18lbs plaster of paris
- 2 large buckets for mixing
- water (either several gallons or a flowing source)
- 100% pure petroleum jelly
- dull cutting instrument (like plastic cutlery)
STEP ONE: ALGINATE LIFE CAST
For this step we needed approximately 2lbs of alginate (available here). This is the same type of material you might find in a dentist's office to take casts of your teeth. It sets fairly quickly and is straightforward to use.
Once the water is added the clock starts ticking. The second it sets (which happens abruptly after a few minutes), thats it. You cannot add more alginate on top of set alginate. We actually overestimated our first batch and made it too runny to build up a mold before it set. Fortunately alginate is one of the more inexpensive materials in this process so it wasn't that heartbreaking to have to take a second stab at it.
Before we mixed any alginate, we spread petroleum jelly over (our actor) Alex's skin in a thin layer to avoid it sticking and getting damaged when you remove it (too much jelly and the alginate will just stuff off) especially areas like eyebrows or whiskers. If you are casting someone with a head of hair (we fortunately had the luxury of a baldy) avoid this area, or protect it with a bald cap prior to applying alginate.
We wrapped anything we weren't casting in plastic (torso, legs, etc.). Alginate is a very mild substance, and stays quite soft to the touch, but it's not what I would class as super-easy to get out of clothes.
I suppose I should note that we provided a way for the subject to breath/live while building up the thick alginate. A couple straws were enough in our case.
STEP TWO: PLASTER BANDAGES
With the alginate in place at least 1/4-1/2" thick, we reinforced the mold with plaster bandages (available here). Alginate is soft and tears easily so it won't support itself or the weight of the material poured into it in the next step.
We only covered the front half to start. We had to be able to get this off of Alex, and if we didn't do it in two parts, they'd be sealed in a durable head cast.
the front portion of the reinforcing plaster bandage.
We cut the plaster bandage into pieces about four feet long and 6-8" wide so it's more friendly to use. After wetting the bandage in lukewarm water, it's folded in half lengthwise (so now it is 4' long x 3-4" wide), and gently squeezed of excess moisture. It should be wet but not dripping. The bandages are applied in overlapping layers until its a nice firm shell covering the front half of the subject.
Before we moved on to the back half, we applied a nice thick ribbon of petroleum jelly to the edge of the front half, approximately 1" wide, all the way around. This ensured we didn't lock the two halves together where they overlap.
The same process of the first half is repeated leaving a slight gap (1/8" or so) between the two halves. Once this is completed, we took one final piece of plaster bandage, folded over a second time to make it twice as thick, and covered the gap (making sure we did not exceed the petroleum jelly buffer on the front half).
STEP THREE: DEMOLD LIFE CAST NEGATIVE, REBUILD
The plaster bandages set up relatively quickly. Once they were dry throughout and solid, not flexible to the touch, we gently pried the back half off. We took extra caution not to damage either the soft alginate beneath the shell, or harm Alex underneath that. No sharp objects. We set the back portion aside.
With a dull object like a coffee stirrer or the dull side of plastic cutlery we made a zigzag cut down the exposed back of the alginate mold. The zig zag pattern will hold together much better than a straight line during the mold pouring process.
The moment of truth. Alex leaned forward and held the front half of the shell while we carefully began to loosen the subject from the cast, taking care not to tear the flaps of unprotected alginate.
Once free, we placed the back half of the plaster bandage shell back on the cast and carefully pressed the alginate inside back into its molded position. The zig zag cut holds much like a zipper.
This is the negative mold of the life cast.
STEP FOUR: POUR POSITIVE MOLD
We mixed enough plaster of paris (available and virtually all hardware stores) to fill the empty mold. We also placed an empty water bottle in the mold's cavity to reduce the weight and plaster used.
STEP FIVE: DEMOLD LIFE CAST POSITIVE
We allowed the plaster ample time to fully set before demoldig. Unfortunately I don't have any photographic proof I actually finished this specific step, but it looked like a slightly lumpy version of Alex (this is because we didn't do a knockout job in the alginate step, and some areas we a little thin).
The alginate is discarded as it's not designed to last more than one cast. It's pretty much destroyed in the demolding phase.
It is this plaster head onto which we will be sculpting the look of our new mask...
In the next post: the clay mask sculpt, the resin negative mold of the cast, and the final silicone mask.
–Tyler
*For any questions on this process, or our short film, Satori, feel free to hit us up over on our contact page.
**Special thanks to the fellas at Brink in The Yard Mold Supply for sharing their knowledge of all the materials needed throughout this process.