: reading through the last threads on epoxy/carbon coamings a couple guys
: mention them softening in the heat. Is this common?,,would other epoxies
: be better for the application or using white fill coats, or vinylester
: resins? I know that obviates the cool carbon finish but if you can't
: afford the exposure that sounds like a problem.

Lee,

If softening with increased temperature is an issue, then the choice of epoxy can have an effect. To compare epoxies, look at the heat deflection temperature or glass transition temperature (Tg). I just had a quick look at the MAS site and didn’t find any values for their stuff – same with RAKA. West System publishes values for their products. Fiber Glast has a short comparison table on their page, but it only has Tg values, and only lists WEST ProSet. But, if we add the Tg value of 137 F for West 105/207 to the Fiber Glast table, it looks like a coaming built with West 105/207 would soften at a temperature around 50 F lower than one made with Fiber Glast 2000/2060. However, I doubt that there would be that much difference between the brands that we commonly use.

Making the coaming thicker will help prevent noticeable softening. I used around five layers of 6 oz carbon covered with layer of about 0.045 in veneer, and have not noticed softening. But the light color does help keep it cooler than if it were black.

Sam