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Paint over CPES?

bgary

Advanced Beginner
Blogs Author
I did a search but didn't find an answer.

i plan to seal some plywood with CPES and then paint to match the inside of a locker.

A mirror-like finish isn't important, but I want it to stick, so...

...any prep tips? Just scuff it and then paint? Or...something more?
...do I need to worry about scrubbing off amine blush?
...any recommendations on paint? Would be happy to use a household grade paint...if it will stick. Or something boat-y if that's what is needed.

Thanks,
Bruce
 

JSM

Member III
Just used Smith's CPES to seal two sheets of teak and holly ply for my new sole. Looks like Smith's has re branded their product for use as a primer. If you have any questions you can call Smith's 800 number and talk to Steve Smith directly. Really helpful and interesting guy to talk to.
http://www.smithandcompany.org/CPES/index.html
 

bgary

Advanced Beginner
Blogs Author
you can call Smith's

I called Smith's this morning. Yes, they've rebranded as an all-purpose primer.

His guidance to me was "encapsulate with thin coats, let the solvents evaporate completely, and then paint with whatever you want. No other prep needed".

I asked if there were particular types of paint that stick well to the CPES, he said "any kind". Which... I'm not sure if that was an answer or a position.

I placed a call to Interlux to ask if they recommended a primer on top of the CPES if I decide to use Brightside. Haven't heard back from them yet.

Has anyone used (for example) a household latex or enamel paint over CPES?

B
 

tenders

Innocent Bystander
Brightside over CPES or any other epoxy will work well without additional primer, if you're not too concerned about smoothness, but I'd definitely scuff the CPES first.
 

bgary

Advanced Beginner
Blogs Author
Update...

Following the instructions, I sealed the wood for my shelves with CPES. I used the cold-weather formula, because temps in my garage have been mid-50s lately, and followed the instructions for mixing and cure-times.

First coat came out fine. Second coat stayed tacky long after it should have set up.

So I called Mr. Smith and asked if that was normal. He said it's possible the wood had been adequately saturated with the first coat and that the second coat never soaked in. Yeah, okay, that sorta makes sense (it is, after all, a sealer). He said best thing - if I was really worried about it - was to sand it down to bare wood and re-do the second coat.

That seemed.... odd. I mean, if the wood was so well-sealed that more CPES wouldn't penetrate, sanding it down to bare wood and re-coating would basically just be re-doing what I'd already done.... wouldn't it?

Anyway, I'm not super-worried about this wood - no sign that there's been moisture in this locker, so the shelves shouldn't be wet - so I ended up wiping the wood down with acetone (which reduced the tackiness significantly), lightly sanding with 120-grit to cut the gloss, and painting. I got some ValSpar exterior paint at Lowe's, color-matched to the inside of the hanging locker, should look okay. Especially for something nobody will ever look at but me.

_/)_
Bruce

PS - there must be something to this CPES which is, in some subtle chemical way, significantly different from "normal" epoxy. I've had leftover epoxy go off in the cup after a job is done, and it comes out in a hard chunk. The leftover CPES took FOR.EV.ER to "go off" (it remained liquid in the mixing cup for well over a week), and at this point (I think three weeks after mixing it up) it's about the consistency of jello. Not sure what that means, but I thought it was interesting...
 

bgary

Advanced Beginner
Blogs Author
I've used the Smith CPES several times and not had it act like that.

I wonder if there's something different to the "cold weather" formula.

Or if they've changed their formula (I noticed he's changed he branding, it's now being pitched as "the world's greatest primer (tm)"

I also wonder whether a second coat was entirely superfluous. My guess is that, as Mr. Smith said, it basically sat on top of the prior layer and didn't add any value. Since the CPES is supposed to bond with the cellulose in the wood, it almost makes sense that (without that contact) it didn't act right.

Nice pram!
 
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tenders

Innocent Bystander
If you’ve got CPES or any other epoxy that hasn’t cured in a week and is like jello after three weeks above 50°...something is wrong. As in, it wasn’t mixed properly, the ratios were reversed, or the hardener is chemically bad. Epoxy cures faster in a pot with limited surface area than it does in a sheet.

Is it possible it was very cold/thick when mixed, and wasn’t mixed thoroughly?
 

JSM

Member III
Just finishing up on new teak and holly cabin sole. Sealed both sides of the plywood pieces with Smiths CPES. The first coat soaks in and seals the wood. Subsequent coats sit on top and probably don't do much more to seal the wood, but what they do is to fill the grain in the wood and keep it from "telegraphing" to the finish coat.
I applied three coats of CPES to the tops of the pieces followed up with four coats of oil based polyurethane floor finish. Very happy with the results.
 

bgary

Advanced Beginner
Blogs Author
...something is wrong. As in, it wasn’t mixed properly, the ratios were reversed, or the hardener is chemically bad. Epoxy

Could be. I did both batches exactly the same
-- cold-weather formula (says "4 hour pot life, full cure in 2 days" at 50F)
-- temps above 50F throughout
-- containers had been in garage for day, so they were at ambient temp
-- mixed equal portions of part A and part B (measured 8 oz of each)
-- stirred thoroughly

First batch went off just fine; hard to the touch the next morning with no tackiness.

Second batch... not so much.
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
I'm looking at 12 sole sections of new T&H plywood treated yesterday with CPES. The surfaces seem sealed sufficiently. They're hard and somewhat glossy. They can absorb very little more, it seems. New CPES on test pieces tends to pool a bit, leaving discoloration as it cures.

I'm going to leave CPES at one coat. The sole will now get 6 or 8 coats of Schooner varnish, which is plenty of seal.

CPES capture.JPG
 
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