The Rot Doctor


Subject: CPES on paint
Date: Sun, 18 Jun 2000

I've had some very good results with the CPES in the stringer /bilge/keel areas of my boat, as well as some rather surprising results on my side decks. They are mahogany plywood and the top ply was lifting severely on some spots. Because of this I couldn't remove the old varnish safely without destroying the veneer ply. I plan on re-decking next year so I didn't want to use any extreme adhesives. This may sound dumb, but here's what I did: chipped, scraped, and sanded whatever old varnish that would come loose; applied combinations of carpenter glue and (wood appropriate) super glue and then clamped it down to set up. After about ten minutes I let up on the clamps and swabbed her down with CPES. Clamped down again over night and the next morning the whole thing was hard as a rock. I put another coat of CPES and this time the remaining varnish lifted at the edges - nice and soft - which I scraped off with a putty knife. I feathered this down and applied one more coat of CPES ( so far I've used only about half a cup of this stuff). This time everything looked solid and I proceeded with the Epifanes. Amazing!! The side decks have now descended on my list of things to do. But the real reason I called.... I'm sanding the white hull sides now (not to wood, it's plywood/MDO) and there are bare and thin spots I plan on applying cpes to. Will localized spots affect how my primer works (Brightsides) or should I just CPES the whole damn thing? What's the best cleaner to use (MEK, alcohol, thinner etc) before application? If you're still awake after all this, I appreciate the help.
Rob W.


I'm awake! I'm awake!

Yes, sometimes some rather amazing things do happen when CPES is combined with other adhesives and finishes. We have found, for example, when 3-M's 5200 is applied over CPES less than a hour after application (but more than 15 minutes) at 70F the bond is extraordinary, virtually unbreakable. The same applies to paint and varnish finishes. Apply the CPES, wait about an hour, and then go back and apply the first coat of the paint/varnish. VERY good adhesion, far superior to any other primer.

MDO is a bit different, as you know. To directly answer your question I would spot-apply the CPES, give it an hour or so (or longer) to dissipate the carrier solvents, and then apply your Brightsides primer and go about your business.

We believe the best cleaner prior to CPES application is lacquer thinner, which you can get at most paint stores.

And thanks for your note on the CPES and your side decks. You see, sometimes you get lucky!