MOVED
depends man ..do you have the mask in a mold? ...using a two part expanding polyfoam works best if the mask is still in the mold...its expansion rate can cause a mask to bulge and deform if it isnt in its original mold. You can do small batch pours with very quick ( and I mean fast) brush ups to create a layer around the inside of the latex ..but this will only give enough to add support ..not enough to foam it snug for your head ..best bet is to cut sofa foam and glue it in using super 77 spray adhesive