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Well, let me say this about that , and also answer publicly some questions I got from Pete Rudie about strip-built craft, since there is some confusion growing here.

As I understand it , strips of wood are edge-glued, an assembly made thereby, a upper part eventually glued to a lower part, and fiberglass cloth laid up with epoxy on inside and/or outside.

I have a few materials appropriate for this application. The Tropical Hardwood Epoxy is a flexible glue, made in large part with resins derived from wood, that will work nicely for gluing wood strips together. I originally developed this for Don Philbrick, a manufacturer of classic runabouts in the San Francisco bay area about 1950-90. Russ Donovan operates Philbrick Boat Works today, and it is still in the same [now historic] old building in Oakland. Don was edge-gluing his mahogany planks with resorcinol [it was all he knew of] and had problems with the joints cracking. He asked me to make soemthing that would not crack, and I whipped up Philbrick's Blend. Other boat builders heard about it, and I found it did glue any oily hardwood, and eventually named it Tropical Hardwood Epoxy.

I suggest you use that for wood-to -wood glue joints.

My Layup and Laminating Resin [LLR]is a lower-viscosity product, slightly flexible as is wood because its resin system is similarly derived from natural vegetable sources rather than entirely petrochemical sources. It is optimized for fiberglass layup. Spread a film of it on the surface, and press the glass into it with gloved hands, and in a few minutes the LLR spontaneously wets the glass.

These products do not have solvents that need to evaporate.

Clear Penetrating Epoxy Sealer [CPES] (both trademarks of Smith & Company) has solvents that need to evaporate. The evaporation time is an issue depending on what product goes on next.

The resin system of CPES is similarly derived in large part from the natural resins of wood, and it makes other products compatible with wood because both its resin system and its solvent system can dissolve the natural oils and saps of wood, which entirely petrochemical-derived resins cannot. The reason, simply stated, is that the petrochemical-derived resins are really small molecules, and those systems [West is the classic example] have not enough spacing between their cross-links to allow big woody molecules to float around and stay dissolved in , even after the resin system cures. Thus, many other products will develop a wood-resin-related blush due to improper cure and resin incompatibility. Mine do not, usually, although I have seen soem extreme cases with wood that was not kiln-dried and was totally sap-logged where it even screwed up CPES. Solvent-cleaning and recoating with CPES handled those.

There are other causes of blush, having to do with plasticizer /diluent/extender exudation [West and some others do this, mine and some others do not as I don't use extenders and cost-cutting diluents...benzyl alcohol is one common one, benzyl butyl phthalate is another, and you can see this on the MSDS of those who post theirs on-line] and amine-blush, which comes from not knowing how to formulate products so as to not have that happen. I know and I don't do that, so I have zero or virtually zero amine blush, under virtually all weather conditions. Amine blush is temperature-sensitive, and there are some application variables, but if you folow the instructions I am confident you will have no problems. Over 99% of my customers have no such problems.

Getting back to CPES, its resin system is physically weaker than those of Tropical Hardwood Epoxy or Lauyup & Laminating Resin. See www.woodrestoration for a scientific study of CPES. I therefore recommend it as an impregnant before gluing or doing fiberglass layup on soft woods, but not harder woods. If you use cedar, and Tropical Hardwood Epoxy directly as a glue, and do not squeeze the bejezus out of glue joints but rather put soft rubber pads under clamp faces, it all sticks just fine.

Once the hull is glued up and sanded, CPES is recommended before laying up glass with LLR. It impregnates the random open porosity of the wood and provides a more water-resistant surface in case of occasional damage, and better adhesion, I believe.

My glues are very aggressive adhesives , and will stick just fine to CPES that was put on long ago, and is fully cured.

Some products such as varnish, oil-base enamel paint, some polyurethanes and other things are NOT agressive adhesives, and need to be applied on top of a FILM of CPES that was applied before the CPES is half-cured, so it is the CPES that glues the other thing down. In order to get around the solvent-evaporation issue, CPES is normally used twice, one or more aplications to seal the porosity of the wood at the surface, and then at a later date one does a fresh CPES application shortly before the varnish [or whatever].

The application window for other products on top of CPES depends on solvent evaporation, and I do not know how long it will take it to diffuse out of the wood, and if you use the Warm Weather Formula(tm) in 50 degree weather, it will take a lot longer than a few days, even though the resin system might be cured. [In colder weather you must use the Cold Weather Formula(tm).] These things are indpendent. Ideally , the solvents of CPES vent through the porosity of wood, allowing the impregnated wood to breathe, just not so much nor to so readily absorb liquid water. This is shown in the paper at www.woodrestoration.com.

Solvent-borne coatings can in many cases be applied over CPES that is a few hours old, if not much CPES has soaked into the wood, and if the CPES-solvent-system is compatible with the solvent system and resin system of the material being applied overcoat. Many oil-base enamel paints fall into this category. I did not make everything and so I cannot give blanket assurances of something going perfectly with something else. I am trying here to give general guidelines. Latex paints on wood treated with CPES need a few days between, so as to avoid solvent-blistering of the latex paint, for example. Oil-base paints and many epoxy and other coatings may be conpatible the same day, but coating film thickness matters, as does local temperature. If the solvent-borne coating is applied too thickly, over CPES applied too freshly, on wood that soaked up too much, solvents can be entrained in the coating when it cures, and this degrades coating properties.

Similarly, solventless glues or laminating epoxy products applied freshly on top of CPES impregnated wood will have reduced glue-joint strength.

So, when laying up glass on the outside of your canoes, I would soak the surface with CPES as , for instance, from a foam roller held horizontally and rolled slowly upwards, allowing the CPES to soak in. I would then allow a few days for most of the solvents to diffuse out. Indoors, I would use the Cold Weather Formula, unless it got up to 75 in the shade, and then the Warm Weather Formula. You do not need to sand for adhesion. Everything normally sticks just fine. I would lightly rub down the cured CPES surface with a medium Scotchbrite (tm of 3M) pad, merely to eliminate splinters of raised wood grain that will interfere with your smoothing out the glass cloth. Then, I would paint on the appropriate amount of LLR and lay up the glass.

Sanding for "tooth" is not necessary. Wth these products as I have outlined, you will get a chemical bond if done per the above.

I gather per the rules of this BB I need to put in here the statement that I am Steve Smith of Smith & Company, [actually the guy they named the company after] and I make all that stuff. You can e-mail me directly at smi3thnospam@earthlink.net. My biggest internet distributor of CPES, LLR, Tropical Hardwood Epoxy and other products is The Rot Doctor, founded by Jim Chowning, and you can buy those products through him.