|
I've done a lot of fiberglass, and taken a course at Abaris, and I'd say that if you are having trouble with polyester being weak on a simple panel, you are not handling it right. In composite work, we count on the strength of the fibers; the resin is just there to keep them lined up. The advantages of polyester are that it is compatible with Bondo, and MUCH EASIER TO SAND AND POLISH. The more variable cure times are a great convenience. You can get better properties from isophthalic types, or the strength and toughness of average epoxy from vinylester resin, but it has a short shelf life, so you have to find a shop that uses it to buy a gallon. The advantages of epoxy are low shrinkage and a true water seal, even over rust. It also has less odour and a more manageable health hazard. There is one epoxy, SB-112 from System Three that is compatible under bondo and polyester, but you can usually put epoxy over the esters.
|