Building From Mold without Gelcoat

ondarvr · Apr 18, 2017

rxcomposite said: ↑

I would not recommend that to the boat building community. First, sanding to the glass fibers exposes the fibers to the water and provides a pathway for the water molecule to pass thru aiding osmosis. Any damage to the fiber is a no no. The key is to provide a reliable water barrier.

Second, anything that has "small defects" is bad workmanship and is a headache both for the designer and meeting Class regulations as well. "Print through" is acceptable as long as there is only 1 to 2 % void in the laminate. It is generally accepted that in print tru, the tip is still true to the mold surface and only the valley caused by resin shrink needs to be filled up.

Voids, bubbles, pinholes should be avoided at all cost. It is only in commercial applications where it is not subjected to continous water contact where you can get away with it. Still bad workmanship though.
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I'm not sure who was recommending that, but it is reality when fairing a hull without a sufficient coating of some type.

In the real world I don't see many laminates without defects of some type, hand laminated, infused, prepreg, they all typically have inherent flaws, using some type of in-mold coating puts a barrier between the water and the laminate, plus makes the paint process go much easier.

Depending on the how the boat is going to be used, or the goals of the builder, leads you to the resin choice, on some boats it doesn't matter much on resin, for others its very important.

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Building From Mold without Gelcoat

ondarvr Senior Member

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