The Science Behind The Mask

With the world where it is right now, I thought it would be good to take an objective, reasoned look at some science behind masks.

1994’s The Mask was in many ways a triumph for the practical effects industry at the time. Whole-head protheses were rarely seen outside horror or sci-fi films, let along a prosthetic that could keep up with the exaggerated expressions of Jim Carrey. In 1996, I made a replica of the film’s green-hued headpiece for a friend, winning an award for craftsmanship in a costuming competition. Researching the mask in 1996 – pre-Internet, mind you – was challenging.

Some background: when most people think of special effects masks, they tend to think of liquid latex masks, like the kind you mind find in a Halloween store. Those masks are relatively cheap and easy to make, and they’re fairly sturdy.

The process begins by making a life cast of the actor’s head. If all you need is a pointed ear or a forehead piece (hello, Star Trek), you just cast that bit; Carrey would have needed a whole-head cast. That’s an intense process. You start by smearing a gel-like substance called alginate all over the actor’s head, usually after applying a bald cap to protect their hair. Vaseline is usually smeared over the eyebrows to prevent the alginate from sticking, and a close shave is an absolute must. If you’ve ever had a mold made of your teeth at the dentist’s, then you’ve experience alginate, which is in fact made from algae. It’s a cool substance: you mix a dry powder 1:1 with water, creating a thick gel. When the water hits roughly room temp, the alginate “kicks” and instantly turns into a soft, pliable rubber. For whole-head casts that require some time, you tend to start with very cold water to give yourself max working time. It isn’t comfortable for the subject, who must also be okay breathing through thin tubes you stick in their nostrils. As the “kick” happens, they have to hole absolutely still.

Once the “kick” occurs, you start wrapping their alginate head in plaster bandages, like they used to make arm casts out of. Pro tip: smear denture adhesive all over the alginate before starting the bandage-wrap, so that the alginate sticks to the wet bandages and remains attached as the plaster dries. You try to wrap the head in two halves, either left-and-right, or front-and-back, so that you can remove everything in two pieces.

Once the plaster sets – usually about five minutes, during which time you have to keep checking on your subject to make sure they’re okay in there – you use a blunt edge to gently slice the alginate off. You’re inevitably creating a seam, which is why you usually go front-and-back, putting the seam along the top of the head and along the backside of the ears, where it’ll be less likely to mar important features.

With the subject’s head free, they can go take a much-needed shower while you continue to work. Alginate dries quickly and gets crumbly, so you need to immediately start coating the inside of the head with a thick layer of plaster (or more ideally, a liquid stone substance). Embed thin strips of burlap it he mix to help reinforce the structure and hold it together in case of cracks. Plaster will air-cure in several minutes, as the mix generates its own heat; I prefer to work with a stone “slip” that has to go into the oven (on 150 degrees or so, for about twenty minutes) to cure.

When you’re done, you can cut away the bandages and alginate, and you’re left with a “positive” of the subject’s head. Atop that, you use clay to sculpt whatever alien head features you want. Or in my case, The Mask.

Now, this is where we need to get back to latex. Liquid latex is actually fairly stiff when it’s cured. If it’s going to be thick enough to maintain its shape, rather than collapsing like a latex glove, then it winds up being too thick to “move” much in response to the actor’s expressions. So movies tend to go for a foamed latest instead, which is made using a very different technique. There are two basic types: cold foam and hot foam, with the latter being the more professional-looking and, of course, harder to work with as a hobbyist. I used cold foam for mine. It’s a bit less durable and you can miss some fine detail, but The Mask is smooth and my friend only needed to wear it once or twice.

With your sculpting done, you make another cast, this time of the clay-ed-up head, creating a “negative” of the look you’re after. This cast can usually be done directly in plaster, after you spray a mold release agent on the clay. When the cast is set, you pull it off (you usually do this as multiple distinct pieces, so that you can pull them off more easily), and you scrape all the clay off of your original life cast.

So now you’ve got two bits: a “positive” cast of the subject’s actual head, and a “negative” cast (or set of sub-casts) of the mask you’re trying to create. You re-assemble these, and inject your foamed latex into the gaps. The latex fills the space, creating a fairly lightweight, very flexible foam appliance. On the inside, it’s molded to the actor’s head; on the outside, it’s the mask you were attempting to create.

I did The Mask as two pieces: a main piece for the top and back of the head, and a second for the face and jaw. I later learned that the real movie appliance was more like three pieces, and I totally get why – mine worked, but it was a bitch to get on. I did do the nose as a distinct piece, as was done on the movie. Noses are hard.

You’ve likely heard of spirit gum, but it’s rarely used with foam latex. The foam is more delicate, and spirit gum is sticky stuff. Instead, I attached the mask with a thin white liquid we called Pros-Aid. It’s a bit gentler, and it removes with a pink liquid we called Detach-o-hol.

From there, it’s a quick blast of green spray paint, some airbrushing for the contours, and a lot of makeup – often rubber mask grease, or RMG, finished with a matte powder to help it set and remove some shine. There’s a huge difference between the makeup job you do for cameras – which include incredible amounts of very bright lights – and the job you do for “in personal” viewing. Movie artists can get away with murder, because the lights tend to hide small imperfections. Like, you should see Spock’s ears on set – totally unconvincing. In-person, you have to be a lot more careful, use finer-grained makeups, and the like.

Sadly, in that pre-cell-phone era, I find myself with no pictures of my accomplishment. The day of, I was so focused on getting it on my friend’s head and keeping it on through his competition, that I never bothered to take a snapshot. We’ve lost touch; I know he’s got some photos, but I’ve not been able to track him down. Besides, it’s probably better in my memory than in reality anyway!

So there you have it: some of the science behind The Mask.

One thought on “The Science Behind The Mask

  1. Will Tynch

    I was totally expecting an article on COVID related masks… lol. I hope you’re doing well, Don!

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