Multiple layers of fiberglass

Submitted byEuropa onSun, 11/15/2020 - 09:13

I am finally getting around to glassing the hull on a Hybrid Shearwater. It calls for three layers of fabric, one full, one bottom and keel ends. Should these be done separately or all at once. I think separately would add weight, but all at once might be hard to wet out. Any advice, suggestions?

Thanks, John

Do each layer once the previous layer is still a wee bit tacky. I have always done my layers about 6 hours apart. For me, that means working through the night if necessary. You still get a chemical bond because the expoxy has not cured. If you are not into puling all nighters, then do one layer each day, wash off any amine blush between layers, light sanding with 120-grit between layers. I have never done multiple layers at once...so I will not offer suggestions in that regard...seems like not so good an idea because if you have a problem with layer #2, then you will likely mess up the layer underneath it and have a mess to figure out. 

Robert N Pruden

Thanks, for the reply. I agree with your reasoning, and just epoxied the first layer of fabric. Ithas been many years since I built my original two (Pigmy) kayaks, so I'm sure I'll be back with more questions.

John

Chemical bond is good for strength but not really necessary for layers that are really to thicken rub areas.  I do the same as Robert most times but it is not critical to get a chemical bond on the additional layers.  I think getting the fabric down smooth is most critical.  If this is your first time I would let the first layer cure until the second layer of cloth can move easily on the surface.

sbaxter,Thanks, I was thinking about the possible difficulty in getting the fabric smooth if the previous epoxy was tacky. It has only been a few hours, and I am checking the feel of the surface. Since each layer is smaller, I think it will work out.

JayBabina

Mon, 11/23/2020 - 07:01

However as others inferred, the mechanical bond is fine for our uses. However again, we are all talking about convenience and for me, I hate sanding and I usually did my first glass coat on bare wood in the late evening and the next morning did the 2nd. One of the prime reasons for the seal coat is for air bubbles. So if you go with no seal coat, have the temp in the room up and gradually lower  it once done. The bubbles are often created with rising temps as the fibers of the wood get squeezed.

Tags