I have used it, it is supposed to be very good for all plastics, particularly things like life jackets, dry tops, neoprene, etc. It used to be the industry standard for the dry suit gaskets, but I have since seen another product recomended called something like "Seal Saver" at least that was what came back from Kokatat the last time I had my gaskets replaced. Kinda funny though that it is much more expensive than 303...

As far as on varnish and epoxy I would not worry about it, I have used it many times on both plastic and fiberglass kayaks, the only thing to consider is that it does contain either silicone or something similar that would have be completely removed to add more varnish. I think I remember using it on something varnished once, but I can't remember what.

My favorite use for 303 is probably on nylon fabrics, I have a life jacket that seen at least weekly use, mostly in white water for 8 or 9 years, still going strong, treated a few times a year with 303. Good Stuff. Much better than armorall in my experience.

Bart

: I purchased a product called 303 "The worlds most powerful UV
: sunscreening formula." It was recomended for the gasket on my dry
: suit, fiberglass boats, and plastic sea kayaks. Has anyone used this
: product on their glass and epoxy boats that also have have been varnished?
: I contacted West Systems and System Three and was told "I never heard
: of it." It comes in a spray bottle like Armorall, the car care
: product.