We are about to fix our hoist hole on Hang 20. Since some water got in we are cutting out some of the upper fiberglass around the hole and replace the balsa and then put a layer of fiberglass back on. Since I'm sure most of you have done fiberglass work on your Express before so I thought I ask: Which is the correct weight of the fiberglass mat (I assume mat and not cloth) to end up with the roughly 1 mm thick layer? Or a heavier one first and a lighter one on top?

Thanks!