Working With Epoxy And Fiberglass

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Working With Epoxy And Fiberglass

Postby Dennis In Texas » Fri Dec 23, 2011 5:23 pm

Using marine epoxy and fiberglass is not difficult but if you have never worked with this stuff before it can seem quite scary. It is important to do your homework first. Read up and also ask all the questions you want on this site.

There are a lot of references to epoxy that you can find on the web. Glen-L has a real good discussion on how to fiberglass a boat. Go to click on Boatbuilding Methods then click How to Fiberglass a Plywood Boat. Also RAKA has a real good online manual regarding how to use epoxy. Go to and take a look.

As for where to buy your epoxy, I think RAKA and US Composites are the 2 best marine epoxy suppliers out there. Both of these suppliers have top quality product at very good prices. There are some big name brands out there that charge a lot for the same quality of product.

There are price differences between RAKA and US Composites on different products and there are some packaging and mixing differences on the epoxy resins but overall the quality is comparable so put together an order, add up the order and shipping and go with whoever is less in total.

Here are some quick thoughts regarding glass and epoxy on a Gator boat:

When working with epoxy, use latex or vinyl gloves at all times. For one thing, it is hard to get this sticky stuff off of you once it is on and also, some people either have an allergic reaction to the chemicals, or can acquire an allergy from repeated exposure. If you are concerned about that, use the gloves and a face mask when you work with it. If you get some epoxy on you, dip a rag in vinegar and wipe it off. For some reason vinegar does a good job of dissolving epoxy.

Fiberglass the bottom of the boat without runners, then install the runners and fiberglass them separately. That is if the boat has bottom runners (i.e. keel strips).

I recommend fiber glassing the entire exterior of the boat. It's not necessary to fiberglass the inside. The inside can be epoxied and then painted. Some use bed liner on the interior floor instead of paint.

Use at least 6oz regular weave glass on the exterior for strength and durability. There are other kinds of fiberglass weaves and materials but the regular 6oz will do the job and keep your budget in line. (On my DH, I used 6oz cloth. I have considered, if I was to build it again, using 6oz on the bottom and a lighter weave on the top, say maybe 3oz. The lighter weave is easier to use and it does better on bends. It also takes fewer subsequent coats of epoxy and is easier to finish out)

I think some guys tape the seams first before putting on the big sheet of glass. This does add strength to the seams, although I would contend that the way Gator boats are glued and screwed together, I'm not sure how much additional strength it gives.

Fiberglass won't stick on a 90 degree bend, so all your corners need to be rounded well. That looks better anyway. The heavier the glass, the harder it is to make turns.

In almost all cases, first lay the glass on the dry surface and then pour and spread your epoxy. If you do the opposite it becomes impossible to get the glass laid out right.

Use a squeegee to move the epoxy around and soak the glass. Then use the squeegee to push out excess epoxy from the glass and move it to another location. Next use a foam roller to get the epoxy evenly spread. Don’t put on too much epoxy at a time and don’t let it pool up. It needs to be spread like paint in one thin coat. That’s what the foam roller will do.

Add additional coats of epoxy until you can no longer see the weave. Probably at least 2 more coats.

You will get air bubbles under the glass from time to time. If you can't smooth them out, don't waste time on them because your time will be limited as the epoxy kicks in. If the bubbles are stubborn, cut them with a razor and lay them down. It might look messy but you can sand it out later.

As is true with any part of building a wooden boat, there aren't too many mistakes you can make that can't be fixed, so don't get too uptight about it.

This is meant to be a quick and summarized guide. I urge you to read some of the detailed material I suggested above. There are safety issues and other things that are important to know about before working with epoxy.

Dennis In Texas
Posts: 129
Joined: Fri Mar 11, 2011 3:15 pm
Location: Houston, TX

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