"Saturating" the plywood

[kengrome]

You can get deeper penetration by warming the wood and epoxy, but warming the wood is not always practical. I've done the thinning trick when repairing some rotting window sill wood. But I used denatured alcohol instead of acetone.

Hi Matt,

I just read somewhere (in another forum perhaps?) that alcohol is one of the few chemicals that attacks epoxy. Supposedly this is why the gas that has up to 10% alcohol in it is eating fiberglass fuel tanks in some boats.

Of course I don't have any idea if this is true, but I'm curious about it so I'm wondering if you've seen any evidence of the alcohol you're using possibly preventing the epoxy from curing ... or any other detrimental effects?

[jem]

I've only done that to repair some rotting wood on a window. I never thing for boat building.

The window has since been replaced, so I'm not much help in that regard.

[kengrome]

Here's what I think may be best in many plywood boat building situations:

Treat your already cut and ready-to-assemble plywood panels (and other wood pieces) with coat after coat of diluted epoxy, letting each coat cure for a couple hours or until the next day before applying the next coat. Keep coating and re-coating until the wood simply won't take any more.

Then after the last diluted coat has cured, sand it and use full strength epoxy to build the hull in exactly the same manner you would have employed if you had NOT pre-treated your panels with diluted epoxy.

I think this will effectively fill most of the pores in the wood's outer layers with epoxy after the solvent has evaporated. This should make it much harder for moisture to get into the wood -- regardless of the fact that there are microscopic worm holes in the cured diluted epoxy.

Then by following up using the proper stitch-and-glue techniques with full-strength epoxy to create a boat that is very unlikely to weaken or rot when left out in all kinds of weather.

Of course I still do not suggest leaving the boat out to catch rain water!!!

[LEE SCHNEIDERMANN]

Just wanted to thank everyone who took time to "chip in" on my question.
After hearing the pros and cons of dilluting epoxy, and knowing the situations I tend to find myself when out on the Wapsipennicon, Maquoketta, Cedar, and Mississippi Rivers here in Iowa, I've decided to go for the "heat" and avoid the "thinning".
Working at a small liberal arts college gives me access to ALOT of theater equipment, (ie: lighting).
Having built plant driers using halogen bulbs for the biology department, I think I can apply the same principle to radiantly heat the work pieces and area to sufficient temperatures for good penetration of the epoxy.
Thanks again. I'm sure more questions will arise during the build. It's re-assuring to have such a wealth of practical advice from people I think I could leave my wallet with!

Lee

[lark2004]

I noticed someone very lightly used the term "outgassing"

This is a very good reason to precoat your timber, and the forces of nature behind outgassing, can also be used to you your benefit.

"outgassing" is the molecules of air that are present in the pores of the timber, expanding due to heat and venting into the atmosphere. To use this to your advantage, you can place your timber (well here in Australia we can ) out in the sun to warm up. Then plan to do your precoating in the mid afternoon, bring your timber inside, where it is cooler than the timber's temperature, and brush on your epoxy. As the timber cools down, it help draw in the resin into the timber's pores (instead of air). Then when you do your glssing later on, you won't have to worry about any little fisheye's appearing your nice clear glasswork.