Should have said - a good way to prepare the surface, and to make sure the AS has a chance of adhering to the inside, is to wash the are liberally with rubbing alcohol. Then let it dry before applying the AS. Remember that the surplus AS you see on the outside is almost certainly not doing any good, and stiffening the material can actually be damaging. So be very sparing. Once you've opened the tube the best way to prevent it solidifying in the tube is to put into a freezer.
