The technique will probably save a few pounds, however it is risky. I no longer seal the wood. The reason epoxy manufacturers recommend a seal coat is to get good penetration into the wood. Some manufacturers have even recommended thinning the epoxy to get more penetration. Part of the strength of the wood glass composite comes from the resin soaking into the wood, so you do not want to limit too much. Limiting it slightly is probably not a bad thing.

A potential problem is you must let the seal coat cure before applying the glass. You will probably only get a mechanical bond between the seal coat and the glass coat of resin instead of the better chemical bond. This can be avoided by applying the cloth coat while the seal coat is still green, but you will probably want to sand off dust-picks which will snag the cloth. It is harder to sand green epoxy.

If you wait for the epoxy to cure fully, you risk blush. You must remove the blush completely. My brother peeled the fiberglass off a boat built in a humid basement by grabbing a slight delamination at one end and pulling. In half and hour the glass was completely removed. Not a good thing.

Contaminations falling on the seal coat can also create a poor bond. Oils from your hand which would be absorbed in bare wood stay on the surface of sealed wood and can make a weaker layup.

If the seal coat is too smooth you will not get a good mechanical bond with the cloth coat. You need to sand the smooth surface to achieve the best bond. If you sand through the seal coat you can create blotchiness.

I am currently fixing a boat where some of the fiberglass has delaminated from the seal coat. It took six years for the problem to occur, but fixing it in no fun.

In my book I am a little wishy-washy about the seal coat, but now I do not recommend it. You may be able to save weight, but unless you are very careful you could end up with a substantially weaker boat. The modern low-viscosity resins soak easily through the cloth, so much of the reason for a seal coat has been eliminated.

> I have a question about George's technique for sealing the wood
> before applying cloth. As I understand it, he applies the epoxy then
> wipes it down with paper towels. I assume this is designed to save
> weight by sealing the surface without allowing too much to soak in.
> It would also minimize the surface thickness of epoxy. This makes
> sense to me. (Which shows how much I know. I have just started work
> on a Pygmy Coho after months of reading this board.) Does anyone know
> whether this will save enough weight to make it worthwhile? Is there
> any loss of strength in not allowing the epoxy to saturate the wood
> as deeply as possible? Or does this technique allow full saturation,
> and just remove the surface excess? Thanks