Experienced Epoxy users... CPES?

[doug hodder]

Like mentioned...you gotta really put on the coats regardless of what material you use. My door jambs and galley edges look like molded plastic, absolutely no sign of an end grain on them. I think a number of people get tired of doing the prep work prior to coating and then don't apply enough material to coat it out and figure "that ought to be good". Sort of one of those take the time now, or re-do it later things. To each their own.

In my experience with boat building , the serious custom wooden boat builders today use epoxy on their builds above and below the water line. Doug

[angib]

when sealing end grain plywood with epoxy use as a minimum 3 coats and fill the endgrain until it is smooth.

It's always amazing just how much (regular, no-solvent) epoxy end grain will soak up - it's well worth applying some spare epoxy to the end-grain of a piece of scrap wood and then afterwards cutting it in half to see how far the epoxy went.

And I reiterate my obsession that soaking-in is not a benefit - many 'old hands' seem to think that the further any coating soaks in the better it will protect, but I believe with epoxy this is exactly the wrong approach. What is needed is an epoxy-rich layer where everything that isn't wood is epoxy and that this layer doesn't need to be very thick, it just needs to be 'very epoxy'. For this, soaking-in is a positive disadvantage as it draws epoxy away from the surface, making it difficult to get that vital epoxy-rich layer.

Specifically for end-grain application, it would be interesting to know if using thicker resin, intended for laminating composites not encapsulating wood, might protect better by getting that epoxy-rich surface layer.

[Steve_Cox]

Please, let me take another whack or two at this.

The roof of the gypsy trailer is 1/4" plywood. I put 3 coats of CPES on it, and more on the edges (plywood end grain) It also had 2 coats of epoxy on it. On top of that it had 3 coats of polymer roof coating. I happened to bump into the side of the garage door opening one day and scratched the polymer coating off the rounded edge of the plywood roof. I thought no problem that rood edge is so saturated with epoxy it will be fine. About a week later after a rain, I had a small place about 2 inches long that was starting to delaminate. Turns out even the CPES just left a thin coating of epoxy on the surface and didn't absorb into the wood. Could it be the solvents in the CPES was the only thing to be absorbed? It kinda looked that way to me. Could it be that the solvents in CPES might dissolve the glues between the laminates of plywood.... just something else to worry about

[S. Heisley]

Steve, I don't know of any epoxy that will soak in past the plywood glue, even CPES. That’s the biggest problem.

CPES does help prevent delamination but I'm not certain how that works, whether it mixes with the glue or just provides a water shield to protect the glue that holds that first thin layer of wood sheeting in place.

We all know how insidious water can be. It doesn’t care what kind of epoxy a person uses. All it needs is a little crack and....