Seth, No need to bash on the group. I think the lack of answer is because not many people are using micro with Vinylester. You would be much more likely to get a good answer on the GlasAir list where nearly everything is done with vinylester resin.
The simple answer would be to take a day and do a test on a small piece of left over vinylester, then accelerate the cure with some heat. It think you'll find that it will work OK. I would mix the vinylester and MEKP first and stir to make sure the chemical reaction between the MEKP and promoter is started properly before adding the alcohol. Once applied, the alcohol should evaporate off pretty quickly, leaving the vinylester/promotoer and MEKP to finish the crosslinking process. I'm not a big fan of adding thinners to resins as the thinners evaporate off and leave weak voids. However, with micro, it isn't like you're doing structural work anyway, so there's not much of a down side to it. Vinylester is so tacky, that adding some alcohol to it may make it a bit easier to work with and slow down the catalytic reaction until the alcohol flashes off. I have also used acetone as a thinner with resins when it was necessary to thin the resin. I had never considered MEK as a thinner and would have some concerns about the MEK diluting the MEKP reaction with the promoters in the Vinylester. You would need a chemical engineer to answer the question about the MEK interaction. FWIW, I have always used epoxy based resins (Safe-T-Poxy, West Epoxy, Aeropoxy) for micro filling over top of vinylester. They are easier to work with and after 18 years and 1000+ hours of flight time, I haven't seen any issues with that combination. But there's nothing wrong with staying with the same resins for finishing if you choose. -Jeff Scott Los Alamos, NM > > I apologize for sharing information on this list about the challenges of > actually applying the Vinyl Ester. It was superfluous...sorry! I should > have made it clear that my decision to use Vinyl Ester on a composite fuel > tank was/is a good one based on research and after weighing many other > alternatives. > > Anyway, the original question was whether I could use isopropyl alcohol as > a thinner with Vinyl Ester resin/MEKP. I totally don't mind that no one > can or will answer it. The tank will be finished by next week regardless! > -Seth
