Mix 4 cups of alginate to 4 cups of water. I used Pink House Studio's slow set alginate. This can be mixed with warm water and still have around 7 minutes of working time. It doesn't "snap" like regular alginate giving you some warning that it is setting up.

Apply petroleum jelly to your model's eyebrows, eyelashes and any other facial hair (coated lightly). This keeps the alginate from sticking to the hair. Then apply alginate to your model's face and overlap it onto the plaster bandage. Keep the nostrils clear so your model can breathe. It helps if you have an assistant, but this can be done with out one.