Personlly, I am not a fan of Poleyester resin. It is simpler to use in some ways, but it also has solvents in it and it can shrink out. I know lots of models have been finished with it, but for my money, I would use finishing epoxy. I have not reallly ever coated the balsa first with hairspray/dope. I have heard a lot of good things about it, I just dont, though I have contemplated it I will confess.

Definitely epoxy resin over polyester resin.  The polyester resins are not very temperature stable, will continue to shrink for years to come and the weave of the cloth will eventually show through your finish.  With polyester the warmer it gets, even when cured, the softer it gets so you really have to be careful what colors you paint over it (i.e. darker colors will get warmer and the resin below them will be softer than an adjacent area painted in a lighter, more heat reflecting color).

Any of the readily available epoxies work well - I have a lot of experience with West Systems and System 3.  They wet out well, and a quart of this material will finish many, many airplanes.

Pete

I've been using Polyester for more years than I will admit.

I've never had an issue with anything related to it.

I never paint over polyester resin, I prime it first. The paint goes on over the primer. I use all automotive products.

This model was finished in polyester resin and glass cloth. Primed with Dupont primer. All automotive paints, actually leftovers that were given to me, were used. The flag stuff was masked and brushed with brushing lacquers which are no longer available. The lettering and art was done by hand, actually gold leaf. The black around the lettering and art was brushed with One Shot, sign paint.

The thing was cleared with a two part Dupont clear. Two coats.

"Never change a winning game." This model took best finish award at the WRAM show ages ago.