Fibre Glass Resin and Petrol

It depends on the resin. There are differing compositions of both polyester and epoxy resin systems on the market, some are ok with petrol (I'm assuming that's the fuel in question) and some aren't. I've used Crystic 17789 polyester resin in contact with fuel and it was ok, but you MUST let the resin fully cure for around 4 or 5 days before fuel contact. if the fuel contacts it prior to full chemical cure, it will just soften and make a god-awful mess. Crytstic 17789 is a 3-part resin, consisting of resin, catalyst and accelerator. It cures by an exothermic chemical reaction and the mix quantities are critical for strength. Too much catalyst or accelerator and it can self-combust!! A safer and very similar alternative, visit your local boat chandlery and get a gallon tin of pre-accelerated polyester resin, comes with a small tub of catalyst and costs around £30. As long as you leave it to cure fully, it ought to be ok. I made a bonnet for a hillrally motor using it and it's been regularly splashed with fuel whilst filling up with no problems. Epoxy resins are also available that are impervious to petrol, but they tend to be thicker in composition and are really intended for semi-automated manufacturing processes, i.e. autoclaves and vaccum-bagging. Good luck. Badger.

I thought West system 'poxs were OK for layup type glassing ?

Steve

I did say "tend", not are. Yes, there are thinner composition epoxies around, but never having actually used them, I couldn't name any. The epoxy I used on aerospace carbon fibre was like flamin' treacle! You had to roller it into the cloth by spreading it onto 2 pieces of acetate sheeting, with the cloth sandwiched inbetween. A very messy process, prone to air inclusions and irregular bond strength, even utilising vacuum bagging. Badger.