Thanks! It's a "Lloyd's" and the film squeezes out through black felt on both sides. Vacuum is a good idea. Damp lint-free cloth is too. I'll do both to be on the safe side. The cassettes are new ( from Adorama or B&H, don't remember ) and they are plastic with end caps that unscrew. I've got 5 of those, and I'm a slow and deliberate shooter, so that ought to be plenty. I've got a growing collection of used cassettes with an inch of film sticking out too, which I can probably use if I need more for a vacation...

Cheers!