Ok, here's one for you...
Most of us know gel coat stays tacky in open air, and if you're doing so you should either use wax additive, cover it with some sort of plastic, or have to resort to just cleaning off the surface with acetone before sanding.
However, sometimes I have to do a repair (like today) where I only have gelcoat and no wax, I don't have time to get the right materials (as the customer is leaving at the weekend) and the shape of the repair area is too awkward to cover with plastic (curves in 2 or 3 directions). Todays repair was also quite large (approx 100x30cm) so wiping with acetone was a PITA!
This got me to thinking - would spraying the fresh gel coat with something like silicone grease or hair spray or something work to seal it? I imagine a thin film of something like that would be easier to clean off than the sticky gel coat, and would also leave all the gel coat there to be sanded. In some spots where I'd applied it a bit too thin, the acetone ends up taking it all off, leaving spots that need to be refilled. Also it would be a lot quicker and easier to just spray over it than trying to smooth plastic over.
So what do you think? Does something exist that will work?