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View Full Version : Hardening with CPES?



ahp
12-14-2015, 05:14 PM
I received a quote today from a local dealer of mahogany. Now I am considering Plane B. This would be for the wales and comings of the Ohio Sharpie. Cypress is locally available and not too pricey, but it is a little soft. How would this work?

Plane and cut to size, including scarfs. I will need to scarf.
Stain, including the scarf surfaces
Epoxy the scarfs surfaces and join.
Test fit
Trim as needed
Restain where needed
CPES, one or two applications
Several coats of varnish
Secure onto hull. I haven't decided whether to use screws or nails.

Any advice will be welcome.

Thorne
12-14-2015, 05:45 PM
CPES is a primer / sealer, and doesn't harden the surface very much even with multiple coatings. There is a large difference between epoxy resin and CPES that has been additionally complicated by far-fetched advertising claims and many many posts on this (and other) forums.

So yes, you'll get a slight amount of surface hardening / protection with CPES, but nothing to compare with what epoxy and possibly light glass cloth will provide. I think the cypress will do fine with just varnish, but if really concerned I'd give a coating or two of quality non-blushing epoxy. If you're worried about wear to the outwale, you could use epoxy and 6oz cloth under varnish, but that will only help to a certain point against rough pilings or stone.

mcdenny
12-14-2015, 06:09 PM
I'd be more concerned about the appearance. Wood or slightly harder wood is still going to get dinged up when you scrape against a piling. If you like the Cypress go for it.

I've never used CPS, smelled it once though....

I'd scarph first, then plane, stain, varnish etc. I'd use screws too.

David Satter
12-14-2015, 06:39 PM
I don't really the stuff, I guess it serves it's purpose though. Jamestown Distributors new total boat CPS is nice it has no odor, not to bad to work with. Smiths smells really bad.

Bob Cleek
12-14-2015, 11:10 PM
I don't really the stuff, I guess it serves it's purpose though. Jamestown Distributors new total boat CPS is nice it has no odor, not to bad to work with. Smiths smells really bad.

Most anything that works smells bad. When they take the smell out of it, the stuff isn't worth a damn. Anybody that doesn't like the smell of solvents needs to find another hobby. "I love the smell of solvent in the morning. Solvents smell like... like victory!"

MN Dave
12-15-2015, 11:03 PM
Any wood will be noticeably harder with a coating of hard epoxy and varnish, but the hard layer is very thin, and will only resist light loads. You can gain resistance to grit that is not too heavily driven into the surface, but no thin coating will help against a solid whack from a heavy object. The thin layer can't spread a load and if there is enough pressure to crush the wood, it will be crushed. So the bottom line is that coatings will help soft woods, but you can't make cedar as durable as mahogany with a coating./cypress (http://www.wood-database.com/lumber-identification/softwoods/cypress/)/ honduran-mahogany (http://www.wood-database.com/lumber-identification/hardwoods/honduran-mahogany/)/ scroll down to the chatoyancy video under mahogany for the word of the week.


Most anything that works smells bad. When they take the smell out of it, the stuff isn't worth a damn. Anybody that doesn't like the smell of solvents needs to find another hobby. "I love the smell of solvent in the morning. Solvents smell like... like victory!"
The low odor stuff, if you take the time to read and understand the SDS and TDS, is a low viscosity epoxy that contains at least 70% reactive ingredients, and the solvent is benzyl alcohol. I don't see anything unsuited to the application, in spite of the mild odor. CPES is almost entirely solvent, and they try to hide the active ingredients and the solvent mix. Given that the benzyl alcohol solvent is fairly polar and that the viscosity is pretty low, the stuff should be able to penetrate slightly damp wood. At least it has a substantial solid content. I will join you in the don't try it until you have knocked it approach and resist purchasing a sample.

I don't disagree with the general tendency of effective adhesives and paints to contain solvents that stink. Some of my best (chemical) 'friends' stink, but I prefer not to hang out with them in close quarters.

Dave Hadfield
12-16-2015, 10:40 AM
You could laminate a 1/8" layer of something hard, like oak or ash or cherry, onto the outer edge of the cypress outwale. That's not a big deal. And it's a weight saving over a solid hardwood one.

Just don't glue the outwales to the hull. It can be convenient to remove them by simply undoing screws.

Dave

SMARTINSEN
12-17-2015, 07:03 PM
I seem to recall that the CPES manufacturer recommends staining after sealing rather than before; regardless I would certainly avoid compromising my scarf joint with any stain.

ahp
12-17-2015, 07:07 PM
Thank you all for your opinions and experience.