Sounds like you have this pretty well researched, but...

With the polyester resin I was using.... the laminating resin had UV inhibitors.

You added surface agent (sytrene wax) to laminating resin for sanding layers just as you described. You couldn't sand otherwise because the laminating resin without surface agent never completely hardened.

But, they also make a "gloss" resin, which is an entirely different product that I (and other sailboard builders) used for a final finish coat. It was not just laminating resin +surface agent. The gloss resin had no UV and it came with surface agent already in it. It was also thinner and it was pretty easy to get an even thin coat.

I never tried finishing laminating resin to a gloss finish so I don't know how that would have worked. If the laminating resin doesn't give you the finish you want, you could always slap a coat of gloss on top.

In case you want another resource, the folks at fiberglass supply in Bingen, WA have always been very helpful, although I don't believe they sell polyerstermite protection additive (PPA). http://www.fiberglasssupply.com/

You might be on to an entirely different product line with different properties. Please post some results and let us know how it goes.

: Hi;

: You might want to check my reply to the post above also. The difference
: between laminating and finishing resin is the addition of wax and styrene
: to make the finish layer cure hard (Keeps the air off of it). The shop
: where I got my resin gets it in 55 gallon drums (with lots of UV
: protectant) without wax - When they use it for laminating, they use it
: straight. When it's time to finish a polyester or epoxy layup, they add
: the wax. The wax and styrene mixture is sold separately, I found it in a
: few places on the Internet some months ago. These guys just added some to
: the resin they sold me.

: As to strength, we had a thread on this some time ago, and one of the posters
: reported that the tech he spoke with at one epoxy mfr said that the
: polyester resin should actually mechanically bond better than varnish. The
: local company puts it on epoxy surfboards that see a lot of abuse, and
: they haven't seen a problem in the many years they've been doing it. I saw
: some OLD surfboards in their collection, and they still looked mighty
: good. Epoxies from the 60's were almost brown, however, apparently they
: couldn't make it too clear back then . . . ;-)

: Best Regards, Spidey