Painting

[jaredmatteis]

Hello all. I recentley started working on an old fiberglass boat. (1961 Cutter) So far I'v gutted the old floor and frame, patched quite abit of fiberglass, reinforced the transom and a few other minor things. My next step is painting. A couple friends of mine are artists. I have them spray painting some very cool graphics on the hull and bow. What do I need to do to protect this layer of spray paint? I do not know what type of protecting topcoat is needed. Any advice would be much appreciated.

[gonzo]

What kind of paint are they spraying with?

[jaredmatteis]

http://www.mtncolors.com/s.nl;jsessi...c=2&category=3

Montana. Highest quality aerosol paint.

[gonzo]

It looks like an alkyd enamel. The only thing you can cover that is either another alkyd clear, or a one part polyurethane with UV filters

[jaredmatteis]

Perfect, thanks.

[Jimbo1490]

He can probl'y get away with a two-part poly after applying a clear sealer. Without a sealer it would likely lift.

Jimbo

[jaredmatteis]

I may have messed up here. Im no longer getting the boat spray painted with aerosol as previously mentioned. I have already sanded the sides of the boat with 80grit paper. Id like to leave whatever paint job for next summer and would really like to get the boat on the water right now. Will the sanding I'v done affect anything if its in water?

Thanks

[apex1]

The ark will soak water like a sponge! And very quickly (within hours if you´re good on that) destroy your laminate forever.

[gonzo]

Fiberglass/polyester laminate will not soak water like a sponge. Further, it will not do it within hours. The formulation of the resin in a boat that age will not be affected by some water absortion. It will absorb up to about 20% in weight. That is only the submerged area. Have you removed all the gelcoat or just scuffed it? After all, gelcoat is only resin with a load and pigment. It absorbs as much water as the resin.

[jaredmatteis]

Im not sure if its all gone or not. How do I tell? Im assuming Iv only scuffed it. Whats my next step?

[apex1]

Originally Posted by gonzo

Fiberglass/polyester laminate will not soak water like a sponge. Further, it will not do it within hours. The formulation of the resin in a boat that age will not be affected by some water absortion. It will absorb up to about 20% in weight. .

Sorry Gonzo that is not correct. Once you have the gelcoat removed, the open surface absorbs water on a capillar level quite much. Compression forces, which occur when the boat is on speed, cause severe delaminations in a "wetted" laminate. These destroyed areas maybe small, but they weaken the whole junk. And on top of that, these areas never dry out again due to their molecular structure and behaviour. I will not go deeper into that subject on a chemical base here.
Although the "hours" mentioned have been a obvious exaggeration, that can (and will) happen pretty fast. One season on the water is by far enough to destroy the laminate forever, and there is NO way to repair that.

Originally Posted by jaredmatteis

Im not sure if its all gone or not. How do I tell? Im assuming Iv only scuffed it. Whats my next step?

Paint it!

Regards
Richard