CPES vs boiled linseed oil for varnish base?

[Thorne]

I'm foolishly ignoring Bob S's sage advice to leave my dory all painted, and am sure I'll be sorry and have to grumpily paint over peeling varnish at some later stage...

;- )

However, I'm wondering about the differences between varnish over boiled linseed oil (the oil usually cut 50/50 with turps) and varnish over CPES.

I plan to coat the outside of the transom with CPES as that bit will be in the water somewhat. But the gunwales and seats are the only other parts that I've stripped the paint from and will varnish. The mahogany mast is coated with the linseed oil / turps mix and may not be varnished at all.

Can I use boiled linseed oil / turps mix for several coats on the fir/oak gunwales and fir seats, then varnish over that? Or would CPES be such a better solution that I should go that more expensive / toxic route?

I've read the threads on linseed oil, so it looks like the turps mix will work well to protect the wood. And the first coat of varnish will also be thinned with turps as recommended in those threads.

[Ian McColgin]

CPES makes a super sealer under varnish. Whether you want to bother or not - longer life but at a higher cost - is a question.

I'd absolutely use CPES under any of the modern water based clear coatings, like Sikkens.

For real varnish, I personally oppose any sealer at all. Start with a few coats of 1:1 varnish:thinner. For a super flat finish, fine sand by hand with a hard block under the sandpaper so's you're just knocking off the highs and tack with a rag well soaked with thinner so's you'll somewhat etch the deep parts of varnish that you've not reached with sandpaper. After maybe three coats like that, you can go to less and less thinner so by the sixth coat it's full strength and flowing on to a nice flat surface.

Linseed oil by itself is a poor sealer because it goes black with exposure and under varnish is a poor sealer that diminishes the varnish's grip on the wood.

So called "sanding sealers" will give you OK adheasion and much faster grain filling than three coats of thinned varnish, but at reduced ruggedness. Not good for spars or caprails, OK for cabin trunks and sheltered trim.

G'luck

[George Roberts]

I prefer epoxy under varnish.

[Bob Cleek]

CPES under varnish is the ONLY way to go. This is really what the stuff was designed to do. (Clear Penetrating Epoxy SEALER) I have found that with reasonable maintenance, a good varnish job using CPES as a sealer will last many times longer than the best job without it. I've been using it for maybe twenty years now, so it's stood the test of time. What it does is soak into the wood much farther than any other sealer. Then, if your first varnish coat is applied within three days or so, it molecularly bonds to the varnish as it cures. Makes varnish and paint stick like nobody's business. What destroys a varnish job faster than anything else is moisture getting into the wood and the varnish letting go. This happens first at any break in the varnish coat, like joints that move and screw holes and whatever. CPES soaks the wood and prevents that moisture lifting the varnish. It won't cure rot, or make a boat "waterproof," but it sure will make paint and varnish stick. That's all they ever intended it to do. Worth the cost. A little bit goes a LONG way. Very thin and spreads on like water.

[Bob Smalser]

CPES because your wood isn't in the best shape, given the amount of decay you've already found.

It's useless over paint, tho...you must wood the boat for it to do any good.

[Bruce Hooke]

For the true perfectionists...I did overhear a discussion at the WoodenBoat show that indiciated that varnish over CPES does not have quite the same "visual depth" as varnish over bare wood. But this is really only something that the true perfectionists need to worry about...

[Thorne]

OK -- but it looks like another expensive trip to Smith & Co is in the future...

;- (

Again, thanks for everyone's assistance! I'm trying to learn to do it right after too many years of just faking it, and this forum has proved invaluable in my "reform" process (such as it is).

At this stage I'll use CPES and varnish on the gunwales and transom; CPES and epoxy on the centerboard; CPES, epoxy and varnish on the rudder; and oil on the mast, other spars, and thwarts.

I picked up the WB Series _Planking & Fastening_ book at Powel's during a visit to Portland last weekend -- the articles on wood screws and bungs are incredible! The explaination of how and where to use SS vs Silicon Bronze was really clear, and I've already got the red lead primer from Kirbys to use as a lubricant.

[Bruce Hooke]

At least in my judgement there is not much point in using CPES under (or over) epoxy. I've never seen epoxy fail to stick to reasonably prepared wood, which would be the only reason I can think of for using it under epoxy. The whole point of CPES is for it to soak into the wood so there is even less point in using it over epoxy. But, others may disagree with me, especially on the first point...

[JGPierce]

Bob Cleek,

Looks like you're an advocate for CPES smile.gif I agreee that paint and varnish stick to it like no tomorrow. I've found that I have to give the CPES a light sanding before applying paint/varnish, which roughens it up. I was wondering if you do the same or get around this some how?

Thanks

John Pierce

[JC 72]

Thorne,
Good to hear you are coming along with your boat.I am a user of CPES as well under varnish and paint. Been driving up to Richmond since 1987 to get the stuff. It is great prep/prime for paints of all kinds. Are you planning to dry storing her or is she living at a berth? Covered or uncovered? The reason I ask is, if you want a mat finish that is very easy to touch up perhaps consider a oil finish. Teak oil or some such. If she will live in the garage, or driveway, covered. Hope to see her soon. John Carlson

[JC 72]

Sorry,
Forgot to mention that I would not use CPES under these oil products. And you would be reappling oil frequently. Just consider where she will live. JC

[Thorne]

JC -

I'll be keeping the linseed oil and CPES/varnish bits seperate. The boat is a '92 (ish) fir over oak 13' Chamberlain dory skiff and will be dry-sailed and stored under cover.

Bruce -

I certainly wouldn't use much CPES over epoxy, altho Smith & Co. claim it helps bind the paint or varnish. But underneath epoxy -- sure! The same chemistry that makes it a good sealer for varnish and paint is supposed to make it good for binding epoxy.

Smith's PR stuff is just that, but the technical information seem to indicate that epoxy over CPES is a good thing, and Smith himself says so too...

;- )

http://www.smithandcompany.org

[Bob Cleek]

Nope, I never had any problem with "slick" CPES. No need to "rough it up." The adhesion between CPES and paint and varnish isn't mechanical, it's molecular. The epoxy bonds to the top coating. While I've painted over fully cured CPES without any apparent ill effects, it seems to work just as well, Smith recommends the top coating go over the CPES within a day or two before the epoxy is fully cured.

[Richard Smith]

John,

RE: "I've found that I have to give the CPES a light sanding before applying paint/varnish, which roughens it up. I was wondering if you do the same or get around this some how?"

It is my understanding that it is a good thing to apply the first coat of paint/varnish while the CPES is NOT fully cured. I think Bob S referred to it as "Hot-coating." The thinking is that the coatings link to each other better.

Rot Dr. writes to me in an email:

"You can apply any second coating on top of CPES as soon as the surface becomes tacky to the touch, which can happen quickly in warm weather. The tackiness means that the carrier solvents have gassed-off."

"The above applies to wood in decent shape. On deteriorated wood where the CPES penetrating is deeper, a longer time period is required. We advise waiting for at least three days after the application of CPES to deteriorated wood before any secondary coatings are applied."

"If the surface shows 'slickness', then I would give it a rub with one of the 3-M pads or some very light sandpaper. Not much...just enough to give the surface a little tooth. Rubbed or not rubbed, the surface should be wiped down with acetone or xylol or lacquer thinner before additional coatings are applied."

[JC 72]

Thats right. That is why Smith makes different formulas.If you are dealing with rotten wood you need to follow his recomendations and use the slow cure formula, I think it even comes with a fungicide additive.It will migrate through the wood fibers for up to seven days. I treated all of my exposed DF rafter tails on the bungalow with it. Then I made cardboard forms and rebuilt the missing wood with Smith's fairing gel.That was over fifteen years ago and they still look like new. I've never had adheasion problems with oil based paints over CPES.Thorne I missed weather you are going to store her dry or wet.

[JC 72]

Sorry again. I see that she will be stored dry.
ADD and old age are cathing up.
I've sent to Iain for plans. AUK, TAMMIE NORRIE, and CALEDONIA YAWL.I've discovered why I don't feel fulfilled while doing all this pain staking renovation on the old house. In the end, it's still a house. John

[Wild Wassa]

One of the problems with using CPES over old degraded timber or even water stained timber, is a blackening effect cause by the CPES.

If you are going to varnish over CPES and the aesthetics are important, just beware that this can happen. I haven't tried CPES over a bleached timber (bleached to remove stains) this could be another option.

The foils below (for a Laser II), are an extreme case. Once the timber was dressed it looked somewhat OK, until CPES'ed. They looked so cool with the water stains, that I put clear poly over them.

http://www.imagestation.com/picture/sraid144/pa069102d3eeb6baed46b44de20e7304d/f6838f83.jpg

Photo below. Rudder, the first daub of poly over a physically keyed epoxy, which is over CPES. The dagger, is just an epoxy coat, over a physically keyed CPES. Unless I physically key the CPES, I notice that the epoxy that I use (BP's), doesn't like to stick well.

http://www.imagestation.com/picture/sraid139/p88cb4e5b1e7673b2492b5e0d5d1b3257/f6fea072.jpg

CPES has turned water stains black, no matter what timber, I've used it on.

Warren.

[ 11-14-2005, 03:45 PM: Message edited by: Wild Wassa ]

[JGPierce]

To ask a naive question....what do you mean by "physically keying"? Is this roughing up the surface?

Thanks.

John

[Bob Smalser]

Originally posted by Richard Smith:
I think Bob S referred to it as "Hot-coating." The thinking is that the coatings link to each other better.

Rot Dr. writes to me in an email:

"You can apply any second coating on top of CPES as soon as the surface becomes tacky to the touch, which can happen quickly in warm weather. The tackiness means that the carrier solvents have gassed-off."

I've only done this on a couple old plywood boats now, and I'll defer to Warren on anything to do with paint...but I find applying a high-build epoxy primer over CPES that's still tacky makes the primer part of the wood almost like gluing on another layer of ply. Bump the boat into something hard enough to gouge it, and the topcoats chip but that primer stays put in the worst of dents.

When I'm finished with CPES at one end I begin with the epoxy primer at the other end. If the CPES has set up, I Scotchguard it lightly with coarse red for "tooth" or "keying" before priming...and that's the way I'd do it for varnish topcoats. Hotcoating only works "like to like"....I don't think it'll work hotcoating CPES with alkyd varnish.

[ 11-12-2005, 08:24 PM: Message edited by: Bob Smalser ]

[Richard Smith]

Thanks Bob for the clearification.

And, what are you using for an epoxy primer these days?

[Bob Smalser]

Originally posted by Richard Smith:
Thanks Bob for the clearification.

And, what are you using for an epoxy primer these days?Cheap USN surplus....expired shelf life....but there are several high-build epoxy primers out there.

http://pic3.picturetrail.com/VOL12/1104763/2595357/88346117.jpg

[Wild Wassa]

JGP, G'day.

A physical key is "roughed up," that is as good as it gets but not so aggressive, so that it is 'roughed up'. A physical key is advised when the surface has been allowed to cure well before applying the next layer of epoxy or paint ... but not that roughed up Skipper, if you are after a really fine finish. Too rough and the scratch pattern can be telegraphed through to all the above layers of paint.

I've just started fairing a keel prior to painting, that is showing an #80 grit rough-up through many layers of paint. In fact the paint has shattered because of the overly deep scratches.

In Bob's post above, with the approach that he mentioned, he has employed a chemical key to bond the layers of sealant and high build epoxy.

I'd like to think that if I'm trying to put a fine painted finish on timber (timber mostly) that needs to be physically keyed, I need a fine/uniform scratch pattern on a racing surface. I physically key almost every layer of paint. That's just my preference, when hand painting.

You can see the opalescent surface on the rudder (above), is caused by a uniform scratch. That is a very uniform scratch and was done with #400 grit. I don't scratch any finer than #400 (near top coats) or rougher than #220 (for foundation coats).

If I'm spraying paint, it is almost always chemically keyed. The next layer is going on as soon as the previous layer is tacking off.

http://www.imagestation.com/picture/sraid194/p5d2449c4b859c103e7a418c04165538a/f1763573.jpg

The keel that I started working on today. By the time I've finished repairing the surface, the boat will pick-up a 1/100th of a knot hopefully and there won't be a telegraphed scratch to be seen. The paint is not a semi-matte (or an egg shell) as it appears in the photo, but a glossy finish. That shows how badly, a poorly finished physically keyed foundation coat, can ruin the surface finish in the top coat.

Warren.

[ 11-14-2005, 05:39 PM: Message edited by: Wild Wassa ]

[neptoon]

if you have ever used epoxy as an undercoating for varnish..you would not admit it...or you just did it....repairs are impossible

[Wild Wassa]

Impossible neptoon? I say, it does creates more work at times Skipper but stick with it and tint the new varnish. The more difficult the painting job, the sooner you become skilled and nothing will seem like a problem.

... although I'm squeegeeing on a 'flowcoat' today, around compound curves. Let's hope this one goes on seamlessly, unlike your 'friends' patchy varnish? Otherwise I might be cutting the flowcoat until doomsday. I'm planning my day early, before I stuff this day right up.

I once read about a gentleman painter who only painted in his tweed suit, cool. It would have to be varnish ... it's been a long time since I've seen a (real) gentleman paint. The painters nowadays are such a scruffy lot, daubed in poly.

Warren.

[ 11-24-2005, 12:24 PM: Message edited by: Wild Wassa ]

[Rick Clark]

Either varnish over boiled linseed oil>
50/50 with turps not so for the first coat, should be 25/75 turps this will soak in and adhere much better, then go to 50/50 and hope for a hot day as it takes a long time to dry to the inside, at 50/50 don't apply second coat untill dry and sand in between coats. Yes I am a painter for 35 years among other things. Just that I have always had good luck in this process. Anyway have fun. Rick ;)

[ 11-26-2005, 12:19 PM: Message edited by: Rick Clark ]

[bischoffboatworks]

I'm kinda old fashioned as well. Got trained by an old shipwright and a violinmaker. They both taught me to use 50/50 and bring the mix to a boil, apply very hot. It soaks into the wood like crazy. If a couple coats are put on each year, it can go decades with heavy weather exposure and no stripping.

[bischoffboatworks]

meant to say couple coats of varnish each year. ADD for me too.

[Wild Wassa]

'Fat over lean' or 'thick over thin' they are the terms for reducing the turps or increasing oil in each layer.

I couldn't agree more with the comments above.

That is the only technique with oil based materials that I use. Allowing the layers to harden before moving on to the next guarantees an increase in the longevity in the paint, when hand painting (spraying is speed painting and can be different).

Concerning the violin. After painting, a violin is stored for 1 year before being used? That's what I like to do with the boats I have a free hand on ... I put them away to cure properly.

Commercial work still takes time but doesn't have the luxury of being allowed to cure properly (for all bases but mostly oil based materials) at the insistance of the owners. I certainly warn the owners (after I've painted a working surface) to allow more time than they wish, before the painted surface becomes a working surface. Some don't listen and the phone rings, "I've damaged the new paint."

Back to why oil based materials need to be allowed to set and then harden ... oil based enamel and varnish do not actually dry, not in our life times anyway. They oxodize, then set, then harden and then polimerize but they do not actually dry (reason why we use oil based materials, the oil stays flexible). The four stages overlap as the paint cures.

The three images are of oil based paint, the warnings were given but the owner new best.

Image below is why a violin is stored after painting. The owner and his mate needed to move the boat so the shed could be used for other work. The owner told me the paint surface felt dry and put his hand on the spray job to turn the boat over after 12 hours. I put a lot of work into this boat ... shame about what happened after I finished with it. Looking at the drip mark, they have attempted to hide the damage ... close but just not good enough.

http://www.imagestation.com/picture/sraid195/p7faa85b394a38d85c8246d942890a7dc/f144f875.jpg

This boat could have sat for another month before it even had to move but the owner, a very impulsive character, neeeded to go sailing and trailered the boat after three days of curing. He was warned.
http://www.imagestation.com/picture/sraid195/p450e29aed7449c628a1df2073c907685/f144f87e.jpg

http://www.imagestation.com/picture/sraid195/pe1cd49a7ba0a01e8fabf94f015d28214/f144e558.jpg

The yellow has changed because of the three different light sources (daylight, fluro and late afternoon light) that I photographed the boat under, to best show the texture. Using flash would have hidden the detail.

Warren.

ps, I didn't put this on the "Oooops ... never mind" thread because I did mind after doing so much work. I told the owner how to fix his boat.

[ 11-29-2005, 05:51 PM: Message edited by: Wild Wassa ]

[Thorne]

Does anyone just leave it as an oil finish? A friend is having a super-trad dory built out of local woods with only an oil finish inside and out.

I may do both for some parts of the dory, probably leaving the trad mast and boom oiled as well as the underside of the thwarts. The topside of the thwarts I've started varnishing (well, testing with 40-year-old+ varnish) over a very dry coating of oil/turps.

The head of the rudder, gunwales, centerboard case and transom will be new marine varnish over CPES, and the rudder blade may be just epoxy or maybe glass cloth with epoxy topcoats.

This boat will be dry-sailed and stored under cover, so I'm hoping the UV element won't be too much of an issue, but the varnish is marine grade with UV protection (such as it is).

[ 11-28-2005, 09:31 PM: Message edited by: Thorne ]

[Thorne]

So here's another related and probably equally foolish question -- why use varnish over CPES? Would it be solely for the UV protection, or will a basic varnish job provide more protection for the CPES than another coating of CPES? What if you put a final coat of pastewax over the CPES for scratch protection?

If looks are not an issue (other than being bright vs painted), why not just use multiple coats of CPES? (I'm not comparing multiple coats of CPES to a professional deep varnish job, just basic "bright" finish looks)

These folks deliver their custom wooden blocks with just CPES unless paid extra for varnish over that:

" All products are finished bright w / Penetrating Epoxy, unless otherwise noted.
Add 10% per item per two coats of varnish ( your choice of varnish )"

http://www.woodwater.com/productsp2.htm

[ 11-29-2005, 09:23 AM: Message edited by: Thorne ]

[Ian McColgin]

CPES is very thin, just a grain sealer, and will not build up at all. I see little harm in ending up with just CPES on covered interior surfaces, though in bilges and engin rooms and such I'd still put some paint down I think. For any surface exposed in any way, you want more to protect the wood than just raw CPES.

[Thorne]

I'm using Smith & Co. Low Temp / Winter formula for CPES, and it seems to build up quite nicely on new white oak. I can see layer, drip and fingermarks quite well!

Here's a pic of the centerboard case coated in several coats of CPES. You can't see the finish but it is nice and shiny...

http://www.luckhardt.com/cb-case5.jpg

Major downside to it is that it "outgasses" very rapidly and you MUST use it outdoors or in an extremely well-ventilated workspace.

Is the varnish layer to give mostly UV protection to the CPES, or other types of protection like against scratches?

[ 11-29-2005, 01:10 PM: Message edited by: Thorne ]

[Wild Wassa]

I know what you mean Thorne. When I've put CPES on new timber I don't want to ruin the surface by going any further either. Varnish will certainly change what you have.

Have you considered using Deks Olje #1 over CPES? If you don't want the yellowing, the darkening and the increase in gloss that you get with using varnish, Deks #1 retains the sympathetic look that CPES has.

If you find Decks #1's surface too flat, Deks #2 can be mixed with it until the surface gloss is to your choice. Deks Olje #2 has a very glossy surface when used as a top coat. Not much of #2 needs to be blended with #1, to start the gloss off. I only use Deks #2 to increase the surface glow/gloss of #1. 75/25 will give a similar surface to CPES, test the blend from there. Blended 50/50 Deks will give a gloss, similar to a poly/oil blend varnish.

Deks Olje stays soft for a while and needs to be allowed to cure well before it becomes hard enough to be a working surface.

If you follow Smith and Co's directions and allow the solvents to fully dissipate during cold weather, you need to physically key the CPES before the next coat of 'anything' goes on, I find.

75% (?) of CPES are dissipating solvents, it would cost a small fortune to balance the CPES coat levels and to uniformly coat the interior of a boat with CPES to a fine finish, no matter how small the boat.

Deks Olje is as easy as CPES to get right, easy to coat and just as easy to recoat, unlike varnish for some.

Warren.

[ 11-29-2005, 05:38 PM: Message edited by: Wild Wassa ]

[Rick Clark]

Differnt colors on the finished boat can come from having the wrong color of primer, and not having the primer the same over the entire boat.
I just explained this to a genteman at coffee this afternoon, he is restoring an old (1932 Chevey pickup).
Most people don't realize that you can tint the primer the same color as your going to paint the boat, this will hide different shades of work that you have put on the boat. ;) ie

[Rick Clark]

Different colors on the finished boat can come from having the wrong color of primer, and not having the primer the same over the entire boat.
I just explained this to a gentleman at coffee this afternoon, he is restoring an old (1932 Chevy pickup).
Most people don't realize that you can tint the primer the same color as your going to paint the boat, this will hide different shades of work that you have put on the boat. ;) ie