I use an HSO4+H2O2 at 5:1,allow the exothermic reaction to cool down to at least
90 Degrees C then apply heat if available. Soak mask for 5 minutes at 90 Degrees
and remove and place in a warm 50 degrees C beaker of di water. This will
prevent thermal shock and possible breakage of mask. Rinse to purity in di water
and dip in IPA. Remove slowly and blow dry with Nitrogen gun. Bob Henderson