Sit up in a chair while applying the latex to ensure the mask will look natural and fit properly. Your face shifts weight when lying down.
Put on a bald cap to prevent hairs from getting caught in the latex. Close your eyes and keep them closed while the mask is being made.
Coat your entire face with regular lotion wherever you plan to apply latex so small hairs won't get caught. Coat areas with heavier hair, such as beards and eyebrows, with vegetable oil. If making a full head mask, coat the bald cap and the back of your head and neck as well.
Brush a thin, even layer of liquid latex all over the face except for over and inside the nostrils. Cover the eyelids if necessary -- if making a mask with eye holes, it is unnecessary to coat the eyelids. Leave the ears for last.
Coat the face/head a second time when the latex appears translucent. Repeat the process six more times, then lay strips of gauze over the latex while still tacky to make the mold stronger.
Apply additional coats of latex until you no longer see the weave of the gauze through the latex.
Sit still for as long as possible while the latex dries, then carefully peel it off.