Discolored interior fiberglass- why?

[Rich Stidger]

Maybe this "stain" has always existed, but I just now noticed it after 14 years. The picture shows a darkish area around an interior lamp, almost like a water stain. But I never had a water leak and the lamp is not heavily used so I don't think heat is the cause.

I do have a couple of other areas that have a similar stain on interior fiberglas, but they have always existed. I figured they were just a manufacturing defect- not a big deal IMO.

Does anyone else have these "stains"? They don't clean off with any cleaner I've used, they seem to be in the surface of the fiberglass.

 

[Dan Johnson]

Rich...

I suspect that you DO have a minor water leak that has found the opening in the overhead where the light is positioned and the tannin that has been leached out of the plywood filler between the overhead and the deck glasswork has seeped into the edge of the raw fiberglass at the hole edge and penetrated the fiberglass below the gellcoat surface. This could be why you can't remove it.

I've had several "stain trails" of a light tan nature leading downward over my overhead fiberglass in my H34 that came from port leaks that have now been caulked and have not returned.