Spray Foam for a mask?

Personally I'd be concerned about wearing a mask made using spray foams, wondering all the time about reactions with direct contact on skin I have used sheet foam but it was applied to a papier mache understructure. The strength of papier mache can depend upon the type of paper used. Most often people will use newsprint since it is inexpensive and readily available. Manila,however, when used is much stronger. I have used old manila folders as well as new ones and even sheets of manila purchased from paper supply companies. With just two layers of manila used the dried piece will have a wood like sound to it when you tap on it. Three layers of manila will give you the same results as four or five layers of newsprint. Manila softens when crumpled up before being added to the paste and holds up better than the newsprint when wet. The manila holds up to sanding out rough spots. Long story short,manila will make a strong papier mache mask.