Wetting out cloth - how much resin?

Joined
Jun 12, 2014
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NW Iowa
I'm still pretty inexperienced with fiberglass having only messed around with a couple strippers and small parts like seats or patches. I always figured that if the cloth was wet enough to turn clear that was enough resin. Is that true or could I be starving it?

What makes me ask is that there are quite a few times when I think I have plenty of resin applied (glass is clear and the peel ply is soaked through) but when I pull the peel ply off there are still micro-holes through the weave. On one beat up old stripper it was enough to allow water to weep through (below water line) and it took a couple more coats of epoxy to finally seal it up.

Also on a seat mold I recently used with vacuum bagging I had the same issue. The cloth was well saturated and the breather fabric soaked up lots of excess resin that got pulled through the peel ply. Figured I'd have a nice smooth surface but the weave pattern was still visible over much of the mold as well as those little micro-holes in the bottom of the weave. I didn't use enough layers so it was too flimsy. I set the mold back in the seat I was using as a plug and applied a few more layers of cloth. The newly applied resin seeped all the way through the mold on onto the seat (plug) and I was lucky to get the two separated when done. Is this normal?

How do I get a fully filled weave and smooth(ish) finish without multiple coats?

Alan
 
Joined
Jan 8, 2014
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1,133
Location
Minden, NV
alan,
I used to work with resin a lot. In the old days polyester, but then later epoxies and now the good epoxies. The material is forgiving. It does what it is supposed to when the right agents are used that consider the working ambient temperature. Epoxy is expensive. Therefore I like to wet it out with a brush or a squeegee on flat surfaces. Fill surface you are bonding to with a skim coat. It is okay to err on the side of frugalness. Any spots show up white that did not get enough on the first go around. One extra coat is okay because it saves wasted material and usually is neater with fewer drips and runs than one heavy coat. It takes more time to sand out the drips than it does to touch up the white spots.
 
Joined
Jun 12, 2014
Messages
3,340
Location
NW Iowa
There must me some way to get a fully filled weave and smooth surface without adding extra coats after the initial has setup. Surely the guys that are building boats from molds aren't adding fill coats and sanding them smooth. I realize many use a gel coat and then lay up the cloth and resin after that's setup but what about skin coated hulls or just a simple seat that I assume comes out of a mold glass smooth? Is there still a light gel coat or skim coat of resin applied to the mold and allowed to partially setup before laying in the cloth?

Alan
 
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