Mike

The question was about fuel-proofing a firewall. Not about fiberglassing. Two entirely different things.

Polyester resin has it's place, but, anyone using it needs to realize that the surface is waxy after it has cured, and that in order to paint it or apply another layer of resin, the surface must be sanded. Personally, I don't much like epoxy as an adhesive. Glassing is another matter, as is fuel-proofing. If using an epoxy as an adhesive, it's not wise to reduce it, I agree with you there. When it comes to glassing, I prefer epoxy resin because it does not need to be sanded between coats. On the other hand, it sands like a rock when compared to polyester resin.

Knowing what to use and when to use it is half the battle.

JR