> I have been placing epoxy in the panel joints of my Coho. The unthickened
> expoxy has bubbles entrained in the liquid. These are quite small,
> typically 1/16 to 1/8" in diameter. Looking at the joints you can see
> the resulting bubbles after the expoxy hardens. Some of these rise to the
> surface, and will be removed by a light sanding, while others are below
> wood level, and will remain forevermore. Three questions. 1) Is this a
> common problem or am I just looking too close? 2) How can I stop or
> minimize this from happening again? I would really like my deck to be
> clear of this problem. 3) Any input on if these bubbles will impact the
> integrity of the structure? They would be quite difficult to remove. Thank
> you for the help.

Don't be so violent when you stir your resins to mix them. Epoxy does not form gasses as it polymerizes, so any bubbles in there are ones that you put in while mixing. (trapped air) or gasses that escaped from the wood after it was coated (outgassing). These usually show up on flat sides of wood, more than at joints.

Once the wood is sealed with a thin coat of resin you won't get any outgassing from the wood.

A few ideas which might help: After mixing your resin keep it cool, and in a wide, shallow, container so it doesn't rapidly polymerize and most of the air bubbles will float up to the surface, where you can skim them to one side.

Apply the resin to warm wood, late in the day so that as the wood cools it will suck in more resin. This is based on the idea the wood will outgas more as it heats up, which is a situation you want to avoid.

Precoat the wood with a thin coat of resin and let it sit a day to harden. Sand lightly to remove any bubbles and assemble. Two coats of epoxy resin do a very good job of encapsulating the wood, protecting it from moisture for many years.

Don't worry about small bubbles. The reduction in strength is microscopic. If you want to look at this in a positive light, just think of the weight you are saving! More air bubbles mean a lighter boat for its size. (by a fraction of a gram?)

You can drill out bubbles with a 1/16th inch drill bit and plug the holes with a few drops of fresh epoxy resin. Just drill down to the hole and pokes some in, or drill all the way through, and cover one side with a dab of masking tape so you don't get a lot of resin dripping through. If you are going to put galss fabric over the hull, drill on the side of the hull you will be covering, and fill the holes as you go, it just takes a few seconds to leave an extra dab of resin as you apply the cloth.

Hope this helps.

Paul G. Jacobson