RE: Which Hysol and Where
From all I've been told and researched
If you are doing a fiberglass lay-up have to spray a layer of PVA over the final coat of resin to avoid have a thin "sticky" layer of resin that will never cure.
I can tell you on yellow aircraft fuse's the inside has something over it... I beleive it's PVA....
I scrubed it all out.... maybe this is not true of all makes?