CPES, Cetol, or both?

[BrianR]

I'm trying to figure out how to treat my Mahogany coaming around my cockpit (Melonseed Skiff). I know CETOL is supposed to allow the wood to "breath" and I know its done a good job on other applications I've seen. On the other hand, from what I understand, CPES "penetrates and seals" the wood, yes? Therefore, I'm thinking that CPES followed by CETOL would be self defeating, right? Is one better than the other in this application?
Thanks again all....

[ 03-07-2005, 12:06 AM: Message edited by: BrianR ]

[uncas]

Brian R...What you are suggesting may work for you...Whether to use Cetol etc. is gonna be a personal preference...I would never personally use the stuff...some people love it...I also hear that it really does not last a heck of a lot longer than varnish...Have gotten two opinions on that though.
My first impression or the info I have received regarding Cetol was that it was simpler to use and apply.Simpler than varnish..I have never heard anyone who used it because of the properties you mentioned...What you say maybe true of the newer cetol on the market...
http://www.imagestation.com/picture/sraid159/p7c8682e5aaa171d11943fa4ff754ab98/f4fab6da.jpg

I use varnish and will continue to do so...
Good luck in deciding.
PS...when Uncas was built Cetol wasn't around..hence varnish was the choice...So sticking to the original.
jamj

[ 03-07-2005, 07:19 AM: Message edited by: uncas ]

[Thad Van Gilder]

cetol is the cheesiest watered down orange paint I have ever seen.

If you gotta do that route, deks olje is way, way better!!!!!

-Thad

[uncas]

Thad...I agree with you regarding the orange tinge....Again, using cetol is a personal thing...osme people really do love it.
Also, heard rumors that the newer cetol isn't quite as bad...Never seen it on a boat though...So no firsthand info on the stuff.
jamj

[Ian McColgin]

There are variations on CETOL that are less orangy looking and on build up it gets pleasantly dark anyway.

CETOL and DeksOlay are very different. In extensive experimentation I found that for the temperate climate around here (things may be different in Norway) Deks holds up rather poorly compared with real varnish, which may be passing anyway to be replaced with CETOL like products.

CETOL is not quite as durable or as incredibly glossy as varnish but it's very easy to build to a good gloss level, like most folk get with five or so coats of varnish. It'll never get to the perfection of a dozen coats of varnish applied perfects and sanded with 440 inbetween.

Unlike varnish, CETOL can take multiple layers without sanding - bonds better without. This leads to the worst problems since ripples in varnish build like moguls on the ski slope or ruts in the road, exagerating what started small.

To get a nice flat surface, starting with CPES to fill the grain, careful wash of the amine blush and a good flattening with 220 make an excellent base. Application should be nice and thin with a good brush so it lays on flat with no sags or runs. It does not hurt after a coat or two to let it cure and then level with a well sharpened cabinet scraper, perhaps several that you custom grind to match the curves of your caprails or whatever.

A CETOL finish is more easily spot repaired for dings and such, as happen on spars all the time, than a varnish finish. With CETOL repairs, you don't get that wierd mottling look varnish repairs leave. CPES under CETOL is equally easily repaired.

Both CPES and CETOL are waterproof but vapor permiable. You know how so many older boats have trouble keeping varnish on the toerail and such because vapor wicks up the fastenings along the topside planking and covering board and lifts the varnish near the bungs?? This problem is licked with CPES & CETOL.

And that's the best reason for making the change.

[uncas]

Ian...thanks you put the info down in black and white better than I have ever read...the pluses and the negatives.
I know that varnish is not the easiest material to work with but even with the advantages you have outlined above about cetaol...I think I will personally stick with the varnish...and after a lot of practice and more practice to come, I'm actually getting the hang of applying it...

[JimD]

I use Sikkens Cetol over epoxy and like the result. Haven't any idea how uv affects cpes but since cpes is an epoxy product shouldn't it at least be covered with some sort of top coat of one's choice? Either traditional varnish, cetol, paint, etc?

[Ian McColgin]

CPES is only a sealer, not a top coat. Absolutely it needs protection.

[uncas]

Here are some shots of varnish work!
http://www.imagestation.com/picture/sraid160/p0550dc87ba9beebfcac1484d9cb76451/f4e8493b.jpg

and

http://www.imagestation.com/picture/sraid160/pc62dc54475609c84d41641c30c5c806d/f4e855ef.jpg

Think I'll stick with varnish...

[Keith Wilson]

I've had very good luck with CPES with Cetol and Cetol knockoffs, like the West Marine house brand stuff. CPES is a slow-curing solvent-thinned epoxy. It penetrates the wood, the solvents evaporate fairly quickly, and the epoxy cures slowly enough to chemically bond with the film above it. The normal UV failure of varnish is right at the wood-varnish interface. The varnish film itself is usually intact, but the top couple of molecules of the wood are damaged by the UV that gets through the varnish, and the varnish lifts off the surface. CPES glues down the coating above it. Cetol and equivalents have, I believe, a LOT more UV absorbers than ordinary varnish (that's why it's semi pigmented). In my limited experience, the combination of the CPES fastening down the Cetol, and the pigments in the Cetol cutting down the UV penetration, gives you a fairly long-lasting bright finish that's not expensive and is relatively easy to apply.

The orange tint is pretty obvious, although they have "Cetol Light" which apparently isn't so orange. The West Marine knockoff is a darker brown and not so orange, not a bad color on mahogany or meranti plywood, and in my experience it lasts just as well.

I don’t think you should sand CPES, and I have never noticed any amine blush. I’d be afraid of interfering it with the chemical bond between the CPES and the first coat of Cetol. Steve Smith would be able to tell you all about this. It's very important to put the first coat of varnish on before the CPES cures completely; the window is from the time you can’t smell the solvent any more, up to 72 hours, if I remember correctly. I sand a little after the second coat of Cetol to level things out a bit, and apply four or five coats. It’s not as pretty as varnish, but it sure does hold up better.

[Ian McColgin]

I would love to know which things successfully "chemically bond" and which do not.

Hot coating varnish is just plain dumb.

GluVit, a marvelous epoxy sealer, will not chemically bond with any paints, even epoxy paints, I've ever tried over it. It needs to be thoroughly cured, washed and sanded before painting.

I imagine some product lines are compatable with uncured CPES - surely Smith's own ClearCoat is ?? - but I've not dared coating withou first curing-washing-sanding.

The product DeksOlay mentioned further up (this thread? memory sags like an overheavy coat of varnish on a muggy afternoon) is designed to have many coats slapped down on top of each other, especially the DeksOlay 1. CPES is like that as well - you can keep soaking till the grain is full. But that's different than chemically bonding.

[Keith Wilson]

Yes, hot-coating varnish, or paint, or just about anything that cures by oxidation (or solvent evaporation) is dumb. Epoxies, however, including CPES, cure by a reaction between the two parts, and will keep curing no matter what you paint over them; it's not hot-coating in that case. Hey, I'm not The Chemist (and where is he when we need him?) I'm just repeating what Steve Smith says in his literature is the right way to use CPES, or my understanding of it anyway; I could be wrong. It's worked for me.

[ 03-07-2005, 11:20 AM: Message edited by: Keith Wilson ]

[Venchka]

"And now, for something completely different."

Cetol alternative: Epifanes Rapid-Clear over C.P.E.S. on mahogany. Epifanes also makes a more pigmented product called Rapid-Coat. I haven't seen it.

Deks Olje alternative: Norwegian Varnising Oil (from Covey Island Boatworks in Nova Scotia) applied to bare spruce and northern white cedar per the instructions on the can.

The finished product here:
Elisabeth Grace (http://www.imagestation.com/album/index.html?id=4290472089&page=1&g_Offset=16)

Wayne
In the Swamp. :D

[Ian McColgin]

Of course CPES cures chemically. My point about compatability is that while an epoxy will cure just fine between and bond to most stabile materials - wood and metal and what not - and will certainly bond with more of the same epoxy -

Epoxies do not always bond with a covering that is itself going through its own cure.

Were I tempted to hotcoat over curing epoxy, I'd to a test patch with exactly those two products first.

[Con LanAdo]

can anyone comment on Smith's 5 year Clear from experiance?

[paul oman]

I know some boat maint folks that would never epoxy 'prime' their wood - could be a problem for future repair/maint projects.

On the other hand, I've found some boatbuilders recommending just varnish, but thinning the first few coats 50% or so to aid in penetration, etc. - which is about how the CPES works.

paul oman
progressive epoxy polymers

[John B]

As you may know, we have quite strong UV characteristics here in NZ.
Varnish is nice, I use it on all my spars, but to use it and keep it on coamings and the like you have to be prepared to cover it.

Deks Ole drops off. It was soul destroying for me.

Cetol is astonishing in its ability to maintain a finish and can be kept up with a fresh water wash and re application every couple of years or so.
Granted, the cetol isn't going to produce the mirror finish some people like but it soaks in and protects the timber and looks fine to me.
Orange? I don't know where that comes from.never experienced it.