I knew I should've kept quiet...
Latex Mask Making 101
Start with an armature, a lifecast is probably best, but a Styrofoam wig head covered with plaster bandages works well too. For your first one, go with a Styrofoam head.
Mount the armature to a board, about a foot or so square.
Use a non-drying or slow-drying clay to sculpt your mask on the armature.
Make the mask a little large as latex shrinks when it dries, (the amount of shrinkage varies with the solids content) and you'll want to be able to comfortably wear it.
Take care to avoid creating undercuts in your sculpt, (think ball and socket joint). You don't want your mask locked into the mold. Minor undercuts are OK though.
Make the neck large enough to get your head through, and also large enough to get the armature back out of! (and to make it easier to get the mask out of the mold)
Spray the finished clay masterpiece with a couple light coats of Crystal Clear. It's a glossy finishing spray, it makes it easier to clean out your mold later.
On to creating the mold...
The mold must be made of a water absorbing material. As water is pulled from the latex into the mold, it forms the surface of the mask.
Common plaster of paris will work just fine, but it will wear out and lose details after only a few pulls. (you "pull" a mask out of the mold, hence the term) It is also very prone to breaking.
Ultra-Cal 30 (made by US Gypsum) is a very good mold material. It has more strength than PoP and nearly the same absorption.
Hydro-Cal, Hydro-Stone, and FGR, (US Gypsum) are even stronger. They're more for the professional.
Unless you're planning on making a dozen copies, PoP is a good, economical choice.
I'll use PoP in my explanation, but UC30, Hydro-Cal, and Hydro Stone are similar.
This is a simple one-piece mold, no separation line, registration keys, etc. to worry about.
Coat the board with Vaseline around the neck of your sculpt. This will work as a release for the PoP.
Mix a thin batch of PoP and brush it into the nooks and crannies of your sculpt. Alternately, you can dip your fingers into the PoP and flick it onto the sculpt. This is to eliminate any bubbles of air trapped between the sculpt and the PoP.
Have the PoP go all the way down onto the board, you want a good strong mold opening, so make it a bit thick here.
Before this sets up, apply a thicker layer of PoP. Make sure no part of the sculpt shows through.
Apply a reinforcing layer of burlap. Use strips of burlap, soaked in PoP. Work the PoP into the fibers well, or instead of strengthening your mold, it will create a weak layer. Ensure that the burlap doesn't have any air trapped in it, or under it.
Again, before this layer sets, apply another layer of PoP.
Another burlap layer.
Another PoP layer...
By now it's setting up and heating up pretty well, you probably won't have time for any more layers. It should be roughly an inch thick at least. The thicker it is, the stronger it'll be.
OK, while it's curing you can buff the surface, even burnish it to a nice shine. This isn't necessary, but it does make a very professional looking mold.
Go clean up, you are done for the day. Let the mold set up overnight. Sure it cures in half an hour, but it'll get stronger over time, and do you really want to risk breaking it?
Alright! On to the part where you destroy all your sculpting efforts!
Carefully remove the board and armature. This is where a sacrificial Styrofoam armature is handy, tear it out of your mold in pieces if you have to. It may be easier to pull it free if you set the mold in the sun to soften the clay. Take your time, you don't want to break the mold or damage the inside details.
Remove the clay, for this you may want the clay a bit cooler so you can pick out chunks.
This was what all that work was for, so go slowly and carefully!
A fairly soft brush and some acetone, along with a gentle touch can remove nearly all the clay. It'll dissolve the Crystal Clear.
Let the mold dry out in the sun for a few hours, admire it a bit.
Now the first pull!
Don't expect a perfect mask, the first pull will show you where you missed some clay, it may even pull some out.
Do this in a place where you won't ruin the floor if you spill a gallon of latex!
Find a way to support the mold, open end up. A 5 gallon bucket lined with towels often works.
Lightly mist the inside of the mold with water, this'll help prevent bubbles.
Pour some latex in the mold. Gently roll the mold around to distribute the latex. If you have an airbrush, use it to gently blow the latex into the nooks and crannies, and to burst small bubbles.
Set the mold in it's support, have a helper hold it too, and fill it with latex.
Leave it alone for half an hour. This is going to be pretty thin for a mask, it's just the first test pull. This'll help you judge how long you'll want let the latex "dwell" for a mask.
With a helper again, pour the latex back into its bucket and let the mask drain into it for a while.
After it's pretty much done dripping, set the mold over a bucket, neck down, to continue drying. When the dripping has completely stopped, you can lie the mold on its side and aim a hair-drier into it to speed up the drying process.
The latex will shrink away from the mold when it is dry, and should be fairly easy to remove.
Very important! Dust some baby powder (talc or corn starch)onto the fresh latex surfaces. Fresh latex will stick to itself!
Check it for trouble spots that may need more attention, things like voids (bubbles) and thin spots (residue on the mold surface).
Let the mold dry in the sun for an hour or two before doing your next pull. Follow the same procedure, letting it dwell longer, 45 minutes to a couple hours is usually enough.
When it's dry, pull out your mask.
Paint it, hair it if you want hair.
Put it on.
I recommend FX Warehouse
. I've never had any problems with Thea. Personally I've had too many problems with Mr. Goldman's Monster Makers, to ever order from him again. But, he does get good recommendations from many other people.
This should probably be moved to the "how-to" section!