painting fiberglass colors

[Sharon Herman]

Read this somewhere...any truth to it?
....."If you do a google search on fiberglass and paint you'll learn that painting fiberglass colors causes more heat that area and causes the fiberglass underneath to continue curing, eventually breaking down. That's why you'll find most fiberglass trailers in white."

[Chester Taje]

Interesting---I would sure like to read more on this subject.

[Chester Taje]

Found this on FG Boat painting.

http://www.yachtsurvey.com/Paint.htm

[Brian B-P]

Presumably this refers to an increase in net heat absorption compared to not having paint. This makes sense to me only if the paint properties (including colour and surface finish) causes more energy from the sun to be absorbed - and/or less to be radiated away - than the alternative, which would more likely be gelcoat than raw uncoloured glass-reinforced resin.

For anyone wanting to wrap their minds around this, I suggest some research into emissivity and reflectivity.

Older eggs (such as my 1979 Boler) were generally beige, while new ones are generally white, both in gelcoat. I don't see how painting one of those old shells yellow or bright blue or whatever other light colour (even the original beige) would make the heat absorption situation worse. Common sense would would seem to suggest that black might be unwise for most applications, such as mine which sits outside in summer sun, but I don't have any solid evidence for that.

I think the original quote is based on the incorrect assumption that any paint colour will be darker than the original fiberglass colour.

The hints in the link from Chester make really good sense to me - thanks, Ches.

[Benny K]

Gee....could this be why older Corvette cars are running around without bodies on them, especially the black ones??? Not likely! The same holds true for truck toppers/ caps most of which are used gelcoated in quite a number of colors, or are painted over the gelcoat....I`ve never seen one, or had one, with a problem.....their are a lot of fiberglass products around from over 50 years ago in use today.......Is the deterioration of the fiberglass the question, or am I missing something of this discussion???? Benny

[Andrew Gibbens]

I'm not aware of big problems with painting polyester fiberglass in dark colours, particularly for older trailers whose laminate will be well cured.

It certainly does cause a problem with epoxy boats, where dark colours produce 'print-through' where the weave of the first layer of glass becomes visible on the surface - the resin shrinks back at the voids in the glass but stays up at the strands of glass, so the surface follows the shape of the weave. We used to get the same problem where dark sponsors' logos had been applied.

White, or very light colours, are the best functional choice for laminates.

Andrew

[CD Smith]

Gee! Is that true about Corvettes too?