Epoxy bubbles on encapsulation layer

[arm358]

Nearly ready to lay down my fiberglass on my Squirt and have read many different posts and resources on doing it correctly. Planning on doing a light encapsulation layer on the hull, letting it get tacky, and then laying out my cloth on top of it so it sticks and can continue to add more layers of epoxy.

I took some others' advice on this forum and gave the inside of my plywood sheets an encapsulation layer to make it easier later when I encapsulate the inside of the boat. The first encapsulation layer on the inside of the plywood created little air bubbles all over. I read this is good/expected and means the epoxy soaked into the wood well. However, to get those out I sanded the epoxy and put another layer on to smooth everything out. All looks good there.

My question is around doing the encapsulation layer on the outside of the hull before laying the fiberglass cloth. I'm expecting the same scenario: little air bubble bumps coming through the epoxy. Is it a problem to lay the fiberglass cloth directly over these little bumps without sanding them down smooth first? Reading some advice on this forum I didn't see anything about sanding these down first and all the posts about the encapsulation layer says for it to get tacky first before laying the cloth--which means no sanding in-between.

Any advice on dealing with these bumps or will it not be an issue laying the cloth over top of them and still getting a nice smooth epoxy surface?

[kens]

Likely the air bubbles is the wood out gassing upon rising temperatures. This is not likely to happen later in afternoon on falling temps.
Myself, I don't worry too much about this, sand it off a bit and keep moving on.
If you want a pristine clear finish, yeah, maybe put time into it.
My work is usually paint grade thus I don't fret over it.

[arm358]

Thanks Ken - I've actually had this happen every time I've put epoxy on the plywood. Even yesterday evening into overnight (falling temps as you mentioned) and it still happened.

I guess I will just roll with it because I am definitely going to paint the hull instead of a bright finish (my scarf joints weren't the most pristine, but they're quite sturdy!)

[steveh41]

I've seen the same thing happen even with falling temps in the afternoon to evening... maybe the epoxy gets warm enough as it goes off to push out a few bubbles on the first coat in spite of the ambient temp. A little sanding and the second coat should set smooth...

Steve

[Roberta]

I have found a thinner first coat may allow gassing to penetrate easier. Never had much trouble with bubbles forming.

Roberta

[arm358]

Thanks everyone for the replies. I guess my concern is that i can't sand after the first layer because i want to do the wet method of fiberglassing and that means letting it get tacky instead of a full cure before i put the fiberglass on. I guess i will just try to put a very light first encapsulation layer on and see if that does the trick.

[hoodman]

That's weird. I've never had bubbles in falling temps.

[steveh41]

Here's a good reference for applying fiberglass in epoxy over wood:

https://www.systemthree.com/blogs/epoxy ... poxy-resin

You can still get a chemical bond within a window of about 72 hrs, at least with the S3 Silvertip product.

[Roberta]

System Three is a great company with great products and their epoxy book is invaluable and is on line for free. I consulted it for my projects.

Roberta