Posted by LeeG on May 17, 2004

I have no experience making polyester/vinyester kayaks but have used a lot of them and done some repairs. Gel coat is a more flexible sacrificial coating on the glass laminate that affords no structural advantage. More importantly polyester based gel coat will not adhere well to epoxy. You can make an opaque and sacrificial coating that is tougher than gel coat using epoxy. Some folks use graphite in this way but I don't see the value in a heat sink for a material that can start to soften at 175degrees,,which isn't too hard to get at in 95degree heat, sun and no wind sitting outside.

Instead of 1mm of relatively soft gel coat that will abrade away eventually requiring new gel coat you could put <1mm of epoxy tinted with white pigment and cabosil with one coat of white paint. The white paint will scrape away but it'll provide some UV protection and not be noticable as it scrapes away. The white pigmented and slightly cabosil thickened layer can be applied at a latex paint viscosity. It'll take a LOT of careful sanding to get smooth as the cabosil makes for a very hard surface but if you're going for a tough ablative layer why not make it tough. I did this for two friends boats with an extra layer of 4oz s-glass on the bottom "football" area with three fill coats done with the white pigmented epoxy and one coat of paint. I am guessing that any pigmented epoxy that has it's paint scraped off will have little UV damage since light can't penetrate very far. Since the fill coats will be white it only takes one coat of paint to provide coverage. As opposed to an old varnished bottom side where scratches into the glass will require a couple varnish coats. The idea of the thicker pigmented fillcoats is to take the place of 3-6coats of varnish. Use the pigments MAS or West Systems sells,,the little tubes in the "gel coat repair packs" doesn't always cover well.

In Response to: get coat by Adam Bolonsky on May 14, 2004