Varnish, CPES, and Me.

[NormMessinger]

So what did I do wrong?

I wooded Prairie Islander's bowsprit. It was originaly finished with a coat of System Three Epoxy and a couple of coats of Epifanes. After two years sticking out in the weather there was a few spot on the top that stuck out from under the tarp all winter that failed which was the motivation for wooding and going with the CPES/Varnish protocal.

I put CPES on one nice warm morning and laid on spar varnish in the afternoon. Next morning all was well so I put on another coat of spar varnish. The varnish crinkled!

I've since wet sanded and revarnished so all will be well but, ....

Do you suppose I did not wait long enough for the CPES to flash off and cure a little?

[Scott Rosen]

You either put the varnish on too thick, or you didn't give the solvents in the CPES enough time to evaporate.

Was it Epifanes?

[Don Maurer]

I put CPES on and apply the first coat of varnish within 24 hours. I don't apply the second coat for about a week to give the solvents time to disapate. The first time I used varnish over CPES, I noticed that the varnish was still very susceptible to being scraped off 24 hours later. I assume that this was because the CPES ubderneath had not fully cured. Another time, I got some crazing in the varnish after applying it in a heated shed, but turning the heater off over night. I am guessing that the temperature got down too low over night and "froze" the varnish before it had set.

[thechemist]

Wood has porosity.

Anything that has solvents and is designed to soak into wood must have enough time allowed for the solvents to evaporate.

Don't feel bad........I think you would have gotten equally unsatisfactory results with latex paint applied the same day. :D

[NormMessinger]

Hmmm. Latex varnish, now there is a concept. smile.gif

I was thinkin' that said problem had nothing to do with CPES but rather that the first coat of varnish which laid down beautifully had not cured enough for the second coat. Probably was a combination of things including, as my ole pappy used to assert, that I was not holding my mouth just right when I put down the second coat.

Now I'm curious, does CPES also form a chemical bond with water based coatings, clear or otherwise?

[Bob Cleek]

Not that anybody could have predicted it would happen as it did, but... from your description what happened seems apparent. The CPES will cook off and be entirely suitable for varnishing within three hours. (I've actually cut it down to less than an hour on a hot day when it was dry to the touch, but still a bit tacky.) You put your first coat on late in the day. It didn't dry as fast overnight as it would have during the day. Your next coat on top of that ran afoul of the first coat of varnish drying. The CPES kept the first coat from soaking into the wood, as it would have done without it, so the first coat only had one direction to go...up. Seems to me, at least...

[ 04-04-2003, 04:55 PM: Message edited by: Bob Cleek ]

[thechemist]

Originally posted by NormMessinger:
<snip>

Now I'm curious, does CPES also form a chemical bond with water based coatings, clear or otherwise?I cannot answer that without knowing the chemistry of those water-based coatings, and the variety now is surprising.

The fact of water there or not is not the point, rather the polymer chemistry and what reaction mechanisms may be available. My suspicion is that they will bond, but I've not done tests and my masters do not make those, so just try it and see what happens.

Report back with results.

[Ian McColgin]

I believe Mr Cleek has it again.

Thick epoxies are a bugger for maintaining but CPES is a nice sealer.

There is a sortalatex - the water base 'varnishes' like sickens . . .

[ROWE BOATS]

I believe that Steve Smith recommends two coats of CPES prior to any type of finish. The first coat is left to cure from one to three days before the second coat is applied. The second coat is then applied and the finish is applied before this coat is fully cured. I could be wrong, but I believe that this is the recommended procedure.

[NormMessinger]

"Report back with results."

Um, let me think. :mad: :mad: Senior moment, stand by... :( ... :eek: "my whole life just flashed before my eyes. Who was she?" :cool:

:D Ah, there it is. I did put water based trim house paint over CPES on Robyn's, or was it Laura's, canoe. The CPES cured over night so it was not tacky as it was with my varnish, and the paint went on just fine. No telling what kind of paint it was, however. Unless I help another kid build a boat I probably not be using latex over CPES without a paradigm. (The "g" is silent, no body said this would be easy.)

Rowe, I have not read Smith's litererature since I bought the first batch years ago but my impression was one coat would do the job. I think I've gotten that impression from reading here as well. Maybe that was just the answer I was fishing for, eh. It wouldn't hurt too much I suppose to read through that package again.

The main man at System Three, Hendrickson was it?, told me once that to be safe every batch, not just brand, of oil based paint should be tested prior to laying it on their epoxy but as far as he knew all water based paints would cure just fine. ...without getting too specific about the defination of paint.

Thanks all. I have one more question along these lines but I'll start another thread.

Best wishes.

[ 04-05-2003, 11:03 AM: Message edited by: NormMessinger ]

[Ian G Wright]

Really Norm,,,,,

You mixed Baptist and Methodist or Lutheran and Catholic and you expect it to work? We are not talking Marrage here or even social equality. Dear me no.
This is Brightwork whose Other Name is Varnish.
The Varnish God is not Mocked. There is only one true One True Faith. Tremble, Sinner, for you have Transgressed,,,,,,,,,

IanW. ;)

[thechemist]

Originally posted by NormMessinger:
"Report back with results."

<snip>to be safe every batch, not just brand, of oil based paint should be tested prior to laying it on their epoxy but as far as he knew all water based paints would cure just fine. ...without getting too specific about the defination of paint.

Thanks all. I have one more question along these lines but I'll start another thread.

Best wishes.Many water-based paints contain dryers and do actually "cure", meaning polymerize and cross-link. Many latices [plural of latex, eh?] merely have gummy droplets that "coalesce" as first, the water avaporates and, second, much later, the coalescing solvent evaporates. Such coalesced films never do cure and come back off with a variety of solvents. Most latex house paints are of this latter type.

Dryers can get absorbed into pigments with age [shelf-life] or poor mixing during manufacture, and then that enamel or waterborne paint won't cure......; best to test.

[NormMessinger]

LOL (as Cleek would say). Actually Ian, I was hoping for hybred vigor, not an idiot cousin. The fifth coat went one yesterday and for a once knoty old lumber yard 4x4 it is starting to shine.

[mhoffman]

Hey Norm-
was your second coat of varnish thinned? You may have put too much thinner in it which caused the coat below it to softern and expand- having nothing whatsoever to do with the CPES.
Just a possiblity..
Best-
Matt

[mhoffman]

Chemist-
how is the car project coming? As much information as you do with coatings, it better have a really cool paint job...
Matt

[NormMessinger]

Nope, Matt, the second coat was not thinned but I suspect your thought is close. The first coat did not have quite enough time to cure before I rubbed on the second. That there was CPES under the first coat was probably irrelevant.