Builders' Forum Archives
Re: Low Temp Expoy Curing
Posted by LeeG on Dec 30, 2006
$.02 on attempts to hasten curing. The ideal thing is to have a constant 70degree temp because the epoxy will flow easily but 60 can work fine with low viscosity poxy.
The problem is temp variations where the temps increase on epoxy that's used for sealing and glassing. It's not that important for joints and fillets.
It's tempting to elevate temps on fill coats or glassing to get to the next stage but that's where it's the biggest problem, even on cured epoxy. I turned up the heat a few degrees for a day on fill coats over cured epoxy and was surprised to find bubbles at a dozen wire holes even though the surface of the hull was hard cured. I was done with sand/seal/sand/seal but it's bothersome to know there's a few tiny,tiny spots where paint/varnish is sealing the wood and not epoxy. I knew by then to not let temps rise on raw wood but this was on two cured fill coats. On another kayak project the sun came through a garage window onto a section of the kayak. Although the wet-out coat was three days old and the fill coats were all going down fine I noticed a couple weeks later that along the section of the deck where the sun hit it there were tiny bright spots on the weave of the glass. Where the glass strands criss-cross each other a tiny amount of air was trapped that wasn't visible on the deck that was in the shade but the portion exposed to direct sunlight and warming up developed tiny bubbles in a symmetrical pattern. Not really noticable from 6' away but since you're working on things 12" away you notice it.
In Response to: Low Temp Expoy Curing by Dan B on Dec 29, 2006