Question about fiberglass

[patrickbwells]

I am restoring a 36 cascade and am preparing the inside of the hull for paint. Most of the fiberglass is bare but some has paint on it. I scraped much the loose paint off. Should I sand the glass before I paint it? Should I only sand the painted parts or should I sand all of it to create a good surface for the paint to adhere to? Thanks.

[Faster]

I'd sand it all - but be sure to use proper protective equipment. Wear the appropriate filters/respirators, a "sperm suit",gloves, tape the cuffs and wear goggles.

If you're using a power sander, attach a shop vac to the filter port to help keep the dust down and run it while sanding. Make sure you have the proper filter in the shop vac so you don't end up blowing dust all over. You'll need a good shopvac to clean up afterwards anyway.

It's no fun.

[sailingdog]

I would sand all of it lightly... and clean it very well with some sort of solvent to get rid of any oil or wax that might be on it.

Definitely want the full bunny suit with gloves and face mask.

[hellosailor]

I think I'd be tempted to chemically strip the paint, not sand it. Sanding fiberglass is just so much fun, and then you need to solvent wash it anyway, to make sure all the contaminants you just ground in with the sandpaper are off. And then sand it again/more to smooth it. I think I'd rather hit it all with a solvent, or a "peel and strip" type system, then just wash it down and rely on a good primer to stick to whatever the solvent couldn't get off.

In the long run, I suspect this will be faster and cheaper. Just be careful about breathing solvent or using a respirator.

[sailingdog]

Also, if you go HS's route... watch the fumes... they go boom...

[TrueBlue]

I agree with the labor saving aspects of chemical paint strippers. But finding a paint stripping solvent that dosen't delaminate the fiberglass would be a challenge.

[Newport41]

What type of paint is best for interior fiberglass?

[hellosailor]

Assuming the fiberglass is on a boat?

"Marine-grade" two part epoxy or polyurethane paint, with a one-part poly being almost as good. Paints and coatings that will be used in areas where mildew is likely, usually have a toxic mildecide and/or funguside added to them, I'd expect those for marine use. Might get along fine without them.

[soul searcher]

Gel coat. Its basicly resin with wax and color added it sticks good to bare glass but the glass has to be clean. usually requires sanding to expose fresh material. It covers good with two coats but is not so hot for bilges as it absorbs oils. you can gell coat the glass and use it as a primer then go with a good two part polyurethane. Or epoxy. epoxy is a good water barrier.but urethane seems to resist oil better. If you have slick clean bilges and no leaks just use gel coat its probably the cheapest route. white shows all sins.
Matt
PS styrene, or benzene can chemicaly strip bare glass styrene is best but watch out it is very dangerous.

[sailingdog]

Styrene is very toxic, and is absorbable through the skin... so wear gloves and a respirator if you're going to use it.