I also do plaster masks with my middle schoolers, but instead of vaseline
(teenagers with acne problems don't need vaseline!) i use two damp paper
towels. one over the top half of the face and one on the bottom, leaving the
nose open to breathe. They are very successful!
I was going to paper mache sculpture with my 7th graders when i found out i
had run out of paste, so having plenty of plaster cast material i had them
build their armatures out of newspaper and then strip with plaster! they
have turned out fantastic!! until now i had only used the plaster for bowls
and masks. i'm thinking gargoyles next!!