CPES over stain

[Kelsey]

I would like to apply CPES over a "Chris Craft" Interlux stain on mahogany...but I was reading the label on the stain, and it mentions that the stain "may lift" if used with epoxy. Has anyone encountered this problem? Or is Interlux just protecting themselves...thanks!!

[Scott Rosen]

I think they mean that the stain may lift if you use it over epoxy.

The folks at Smith & Co. say you can use CPES over stain or oil. You may want to try a test piece first, just to make sure.

[Bob Cleek]

Not that I'd want to question anything George Kirby has to say about paint, but... yea, it's really a question of semantics. You definitely can use CPES over paints and stains, although what that really means is not readily apparent until you've been there and done that. What George meant, undoubtedly, is that AFTER a piece of wood was ONCE painted, you CAN put CPES down AFTER stripping and prepping the work. There just wouldn't be much point in putting CPES on top of a solid coating of paint because it wouldn't penetrate, which is what it is supposed to do. Your layer of CPES wouldn't be holding on to much more than the paint beneath it, rather than soaking into the wood and grabbing on. Stain is the same, but less so, since stain is not as thick or impermeable a coating as most paints and, in fact, is intended to let paint grab on. Now, CPES isn't going to penetrate the oil from the stain as well as bare wood, but it will hold better over stain than paint... But here's the rub.... CPES has solvents in it which are intended to permit it to dissolve the oils and resins in the wood surface to permit it to better penetrate the wood. Those solvents are incredibly effective and aggressive. Smith ought to can them and slap a "paint remover" label on them. When putting CPES over stripped wood, it is not uncommon to find the CPES lifting the paint remaining in the grain. Definitely test a patch of your stained material before slapping CPES on it. You wouldn't want to spend the time hand rubbing stain into the surface so carefully and evenly, only to have the CPES dissolve it and spread it all over unevenly and then kick off! Could be quite a mess. Some stains don't seem to do this, but others do. Definitely let the stain get good and dry before you attack it with CPES. Let us know your test results and what stain you used if you get away with it.

[Vindo Joe]

I used CPES over Minwax gel stain and it came out great! I will not use interlux stain again as just did not have good luck getting an even color.
The CPES did soak in and didn't lift the stain off. I would use it again in that manner.

[Concordia..41]

Watch that stuff indoors folks. Arm's length and down wind in the rule here, and I can still feel brain cells dropping like flies :eek: LOL - may explain a lot huh???

A caveat about CPES and stain: Remember we're in love with the CPES for its binding properties. I was bleaching Sarah's ceiling boards with Te-Ka Bleach – two part heavy duty stuff and the bleach was doing a marvelous job removing everything including engine grease, rust marks, AND the numbers I'd put on the reverse of the boards with Sharpie marker! I CPES'd and stained and when I wasn't happy with the the stain in some areas I thought, no big deal I'd just run them through the bleach and start over. Nada zilch zero nothing. After CPES kicked, the bleach had less impact than water.

BTW – here's our next debate: CPES then stain or stain then CPES. LOL

CPES first. You'll eliminate the great lifting issue and since CPES darkens the wood, it goes a long way towards evening out the color. You'll end up staining less and what you do stain will be easier because you've already closed the light to dark gap by several shades.

That'll be .02 cents please

:D

Cheers gentlemen!

[Raven 271]

We just applied CPES over Interlux stain(the
interior of a pram)and we had no lifting of
the stain.The stain must be completly dry,we
waited three days(in a heated cellar)before applying the CPES.
You can apply CPES before or after stain,but
I do not think the stain would penetrate into
the wood.
.............and does it SMELL!!!!!! It makes
acetone seem like Channel #5 !!! WE did apply
the CPES upstairs in my shop(it was five degrees
outside)but as soon as we were done,we carried the
pram out to my unheated garage.There is no way
that you could work in a room with a pram sealed
with CPES for any length of time.
After one day,most of the solvent has evap-
orated,and along with it,most of the smell.

[Dale Lewis]

I used cpes over Mahagony filler and stain on the transom of my boat. I was very pleased with the results. There was no noticeable lifting or transfering of the stain. I waited until the next day before applying the cpes. I rubbed the transom down real good and hard before applying.

[Concordia..41]

Raven brought up a good point. The really liquid stains did NOT penetrate the CPES'd wood. The Minwax gel product line worked wonderfully though.

[Seth Wood]

While we're on the subject of CPES odor, the guys that make it tell me that smell can be a good indicator of whether it's cured or not. If you can smell the solvents, it's not quite cured.

This is helpful since you don't want to wait FOREVER to put on the paint or whatever goes on top of it. Naturally, don't go inhaling the stuff until you can't smell it in the air -- which may take a couple days in cool damp weather.

Yep, that's me carefully sniffing my backbone timbers. When I can smell oak again, on goes the paint.

[thechemist]

Originally posted by Seth Wood:
While we're on the subject of CPES odor, the guys that make it tell me that smell can be a good indicator of whether it's cured or not. If you can smell the solvents, it's not quite cured.
<snip>
The solvent evaporation process would not have anything to do with the chemical curing reaction, for that product or other paints and coatings. The solvent diffusing out of typical wood probably takes place at a rate which happens to be about the same as the chemical curing reaction of the A and B resins combining with each other, and that would be why one is a useful indicator of the other.

[paul oman]

Keep in mind that you are simply coating the wood with epoxy thinned approx 70% with a cocktail of solvents (and thus using solvent damaged/weakened epoxy).

Generally solvents don't remove dried/set staining. If you have any concerns you can use similar products containing more epoxy and much less solvent such as ESP 155.

ESP 155 (http://www.epoxyproducts.com/marine.html)

paul

[John Blazy]

So Paul and Mr. Chemist, while we're on CPES & solvent content, what would be so bad with thinning WEST or other 100% solids epoxy with some acetone/toluene about 20% and applying to a well heated substrate for penetration similar to a 50% dilution? Smith & Co doesn't want this brought up, but after getting a five gallon pail of West, I am tempted to use my own solvent blend for seal coating with the 207 special ctngs hardener. I understand that CPES may have reactive diluents to react into the molecular matrix a bit, but how much less performing is my solvent blend? Depth of penetration will certainly be less, but a higher solids product will "in there", at a substantial savings. Yet this still may be good enough for many rot repairs, methinks. Sorry for opening up a can o worms. - JB

[John Blazy]

sorry Paul, for not reading your test results and observations before that last post (saw the link in "CPES over Pine". I'm in total agreement with you, and sorry I didn't buy your epoxy. I just so happen to have a gallon of Xylene, and didn't know it would do well to thin epoxy. Thanks a ton for your research. - JB

[Bob Cleek]

We've talked about thinning WEST System epoxy with acetone, etc., a lot in the past. I've done it, though for the purpose of thinning the googe, not for penetrating epoxy purposes. It does work, although WEST disavows any endorsement of the practice. In my experience, you get a much different result. The EPOXY in CPES seems to penetrate along with the solvents, which drive it in. It is very thin stuff. Thinned WEST goes on smoothly, but the EPOXY seems to just stay on the surface, although in a thinner layer. Different epoxies, me thinks. Besides, I really don't think it is cheaper. There's a lot of comment about the price of Smith's CPES, and, no doubt, retailers are now adding to that. No question it costs more than the booze I used to drink, but a little CPES really goes a LOOOONG way.

BTW, just a comment about the use of it on a swim platform... dunno if you had intended to varnish the platform (that's gotta be a tedious job!) and I doubt you'd want to (too slippery?), but you will have to put something on top of the CPES that has a UV inhibitor because CPES doesn't and will go to pot in a very short time (months if not weeks) if left uncovered in the hot sun.

[thechemist]

Smith has some reasonably scientific tests of what one of their products does to wood, published at www.woodrestoration.com. (http://www.woodrestoration.com.) It is an open standard for evaluating what an epoxy-treatment of their sort does, and anyone could easily compare one product with another using that method.

It would therefore seem that some mauufacturers of some products with some solvents produce some epoxies which are not weakened by solvents for some applications.

You should look to whomever makes their stuff and see what they say. Then try someone's stuff and see if it does what is advertised, and if that is what you want. Look to others and see if they have gotten similar useful results in the same application.

I am not here to sell Smith's products.

Paul has some tests of his stuff soaked into sponges, and Paul seems to be here to sell his products.

This forum has a rule against self-promotion, and it is designed to keep merchants from blatantly hawking their wares so that the entire place does not become what Miscellaneous sometimes does. I have held my tongue about this for quite a while, but since this discussion seems to be devolving into a debate in which one of the parties has not only a vested interest but is arguing the very unscientific generality of "epoxies" and the generality of "solvents", and thus is on very shaky ground, for no such generality is valid, I feel moved to point this out.

West tested their product with some amount of some solvent or blend, and found they should recommend not to do that with their products. Paul presumably found the same with his product(s).

That does not prove that Smith or Raka or whomever might not make some epoxy product that is not damaged by some solvent.

Heck, West itself contains Benzyl Alcohol, a solvent. Go look at the MSDS.

What all this proves is that "epoxies" are different, and "solvents" are different, and chemists who formulate such products are different.

Some of those will make products that are commercially successful because they do something useful, and others may not.

[John Blazy]

I always learn great stuff from you guys - Thanks

[Kelsey]

I actually got through to the folks at Interlux today, and they said that epoxy breaks down the stain on a molecular level...hmmmmm, somehow disolving it. I forgot to ask them this question (maybe someone will know the answer): If this happens, is it immediately apparent? Or is this something that you'll notice a year or 2 later.

[cdm4]

CPES over filler stain followed by many coats of varnish is very common with runabout people. Most manufactures tell you not to use anything they don't make just to CYA. CM

[thechemist]

Originally posted by Kelsey:
I actually got through to the folks at Interlux today, and they said that epoxy breaks down the stain on a molecular level...hmmmmm, somehow disolving it. I forgot to ask them this question (maybe someone will know the answer): If this happens, is it immediately apparent? Or is this something that you'll notice a year or 2 later.Once again, a generality that is false data.

Epoxides do not react with the polyether polymers that are the cured varnish-type-resins that are the binder for the stain pigments.

It IS possible that the strong amines that are in some epoxy-mixes as the curing agent, could react with the ester linkages of those triglyceride oilseed resins. However those amines only exist until the "epoxy" has reacted with them, and the strongest amines go first. West has those, and I doubt they survive twenty minutes after mixing.

Those folks at Interlux may have had some bad experience with some particular product of theirs, in conjunction with some particularly sensitive stain formulation of theirs, maybe even an acrylic-resin-binder "stain", and created in defense that blanket generality.

[paul oman]

It makes sense (cents) to make your own penetrating epoxy using a low viscosity epoxy and nearly any solvent. However, the results of solvents in epoxies can be rather frightening. I suggest you mix up a batch of your favorite epoxy and make some samples cut 0%, 10%, 20%, 30% etc. with solvent . Put about 1/4 - 1/2 inch or so of each blend into a plastic or paper cup and let cure. Now examine the results. You might even put in some 'end grain wood' into the test blends check absorption/pentration at different solvent cuts.

Anyway, you will probably find that cutting more than about 10% or so produces a rubbery mass.

I've have had experience with "old fashion" solvent based industrial epoxy paint too. It too doesn't become completely hard, a thin flim of it maintains its flex - probably not too bad a thing with a 'paint' but certainly not for something structural.

Note that solvents do more than aid penetration ( a good thing), they can result in damage to underlying coatings or finishes (a bad thing), however, to the experienced epoxy user that allow the epoxy to flow off the brush or roller more 'smoothly'. I compare it to using a $6 paint brush vs. a $1 paint brush. I've generally found all the solvents work about the same for the end user, however it appears that MEK works really well for removing non-hardening epoxy better than the other solvents and that Xylene will cut epoxy best for spray application and will not 'degloss' the epoxy (at say 10-20+ % solvent) the way other solvents will.

I believe every epoxy out there contains benzol (sp?) alcohol. Pure epoxy is tar thick and useless without this sovlent additive. Epoxy formulators do not consider this a solvent as it becomes part of the structure and not subject to evaporation - all 100% solids (0% voc) epoxies contain b. alcohol, including the epoxies I have work with that are FDA approved for food contact. Thicker, higher end epoxies, such as novolac resins and/or the cycloaliphatic curing agents are especially thick to start with.

Nonyl Phenol is a common (low cost) epoxy thinner (use with both the base or the curing agent) that is not considered a solvent but does thin and cheaper most epoxies. I haven't tested raw Nonyl as a penetrating agent.... perhaps I should.

Back to epoxies over stain: This topic has come up several times in the boatbuilding newsgroup (rec.boats.building) The lasting impression is that epoxies will bond to oil or water based stained wood without problem.

Seems like this seemingly harmless thread regarding epoxy over stain has expanding to cover penetrating epoxy characteristics and in so doing has (as this topic always does) ruffled a few feathers. Truth is that there epoxies come in lots of flavors, fortunately for those of us that build, sail, row boats (and are in the business) the differences usually are not great enough to mess up anyone's project not matter what products they use or believe in. Perhaps that's way there is such strong debate and differing views, they all work well enough that everyone can be at least partially right!

paul

[capt jake]

Wow! I have learned a lot here on this thread! Thanks folks, and that includes you Mr Oman and Mr Chemist! Oops, forgot Mr Cleek!! Heck, thank you all.

thanks!! smile.gif

[ 01-25-2003, 11:12 PM: Message edited by: capt jake ]

[thechemist]

Originally posted by paul oman:
<snip>I believe every epoxy out there contains benzol (sp?) alcohol. Pure epoxy is tar thick and useless without this sovlent additive. Epoxy formulators do not consider this a solvent as it becomes part of the structure and not subject to evaporation - all 100% solids (0% voc) epoxies contain b. alcohol<snip>I do not believe that every epoxy out there contains benzyl alcohol, and I do not believe that they are useless without it. My employer's company does not use it at all. I am not permitted by my masters to discuss specific formulation technology, so suffice it to say that I and many other chemists do not need to use this material.

Further, it is false data that benzyl alcohol becomes part of the structure and not subject to evaporation. This was promoted twenty years ago by Pacific Anchor Chemical Company [before Air Products bought them, because they were a LARGE user of this chemical in their cycloaliphatic formulations which do not cure at room temperature without large amounts of it in the mix. The California Air Resources Board did not buy that, and found that it did evaporate out of a formulation, albeit slowly.

The California Air Resources Board classified it as a VOC.

You can take any such product containing benzyl alcohol and cure it in a a puddle a sixteenth of an inch thick. Make about a hundred grams of it, and put it in a 200 degree F oven with circulating air and an exhaust, and weigh it every twelve hours on a scale with ten-milligram resolution. You will find that easily half of the formulation content is gone in a week or less.

[paul oman]

Lighten up! No one is attacking your technical knowledge.

Very few of us go boating or boat building when the temps hit 200 degrees F. Benzyl Alcohol is a common epoxy component in solvent free epoxies. And at normal temperatures does not come out of the epoxy mixture. Repeat your test at real world temperatures and you will not see a weight loss. Look at the solvent free (0% VOC) marine epoxies (nearly all of them) like from WEST, Progressive Epoxy, System 3 etc. and on all their MSDS you will see benzyl alcohol. I'm often wrong about a lot of things (just ask my wife or my mother!), but I have several chemists/formulators (like yourself, but self employed) that make my epoxies and they would stand behind me on this one as would the FDA lawyers who obtained food contact approval for one of our epoxies with unusually large amounts of Benzyl Alcohol. If that bothers you, better stop drinking milked purchased at the store.

At elevated temperatures epoxies can break down and release gases etc. This is not the same as regular solvent release. At elevated temperatures solvent free items like wood, plastic, and even people, all outgas (some of us outgas too much even before we're roasted. I always thought it was the chili beans I used to eat at lunch!). I would rather be in a burning building full of epoxy rather than a burning building full of tupperware.

Anyway the debate over benzyl alcohol in epoxy is a meaningless issue to the epoxy end user. How about accepting a flag of truce?

paul

[thechemist]

Benzyl alcohol is a solvent. I offered it as a counterexample to your false data that all solvents damage epoxies. You gave other false data that all epoxy products use benzyl alcohol and are useless without it [or whatever you said earlier].

The fact that our government approves as "food grade" products that contain it does not mean much. They have also approved for food-grade tank linings epoxy products whose curing agent is methylene dianiline, an excellent carcinogen.

The fact that boatbuilders do not roast their boats at 200 degrees does not mean that it is not a VOC. You said it was not. It is. The California Air Resources board has classified it as such, and uses an elevated temperature oven test to make that determination. They found that it does evaporate out of products that contain it, just not very fast. You have been given false data and are forwarding it.

[ 01-27-2003, 04:22 PM: Message edited by: thechemist ]

[Peter Malcolm Jardine]

I found this in the archives while I was looking for CPES threads. Man, I miss the Chemist.

[Bob Cleek]

Not only do I miss the Chemist, but I miss threads like that which actually provide some useful information. WAY too much newbie BS these days. Not that everybody has to get a start somewhere, but wading through dozens of posts from people who don't know their ass from a hole in the ground about what they are saying to find a nugget of wisdom here or there gets tedious.

Okay, flame away!

[yzer]

Very interesting posts.

I just use a couple of coats of Pettit Clear Sealer over Interlux filler stain followed by varnish. I allow the stain dry at least three days before sealing. Two coats of clear sealer can be done in a day and then I'm ready to varnish the next day. I've never had a problem with lifting or disturbed stain. My exterior varnish is well maintained and now going into year 14 with the boat kept in a covered slip.

[GRussell]

...wading through dozens of posts from people who don't know their ass from a hole in the ground about what they are saying to find a nugget of wisdom here or there gets tedious...
From my knothole, all this verbage seems somewhat homogenous and I find it very difficult, if not impossible, to separate the nuggets from the alleged BS. What to do?

[Feazer]

WAY too much newbie BS these days. Not that everybody has to get a start somewhere, but wading through dozens of posts from people who don't know their ass from a hole in the ground about what they are saying to find a nugget of wisdom here or there gets tedious.

Very well put and the reason I am inclined to not waste anymore of my time here. You can offer advice distilled from years and years of hands-on experience and in five minutes it is run over with some of the most preposterous statements from responders with no technical depth other than the last issue of WB and eventually buried to the point where nobody can find it or use it. What's the point. Only so many hours in the day and I for one am not going to waste it arguing or retorting to this kind of chatter.

[KAIROS]

Tangential comment on CPES from recent experience:

Probably all epoxies lighten and become somewhat opaque if not protected from UV light by your choice of finish. I have seen it on some non-boat projects for which the appearance did not matter. If it happened to a piece of wood I had spent much effort to get looking beautiful, it'd be discouraging.

We sealed our raw-wood cabinsides (ribbon mahogany) with CPES. In two places where the CPES was applied, when the boat was inside a shed, shafts of sunlight did reach the unfinished surfaces. Those areas are noticeably lighter and the finish more opaque now......and there was only 2 or 3 days between when the the first coats of CPES went on, and when a UV-protective finish was applied 'hot' over the final coat of CPES.

Maybe this is not surprising to others, but this change in the appearance of the final result, with such a short bit of UV exposure, happened much faster with the CPES than with regular epoxies I've used in the past.

[KAIROS]

.....I can always get a different take, and although I might use my original solution, I usually get some helpful advice......

Yes, keeping your mind open to a broad range of ideas is important, whether from newbies or those of vast experience. Wading through it all may be tiresome, but essential if you are going to feed your mind and let it glean the wheat from chaff. Several times when working in my field of expertise (not wood boats, obviously), I have been startled at a newbie's perspective on something I had been working on for months. I have to fight that seemingly natural progression toward a closed mind, which comes with age, daily.

My signature, below, sums up my point.

[Feazer]

This thread and Bob Cleek’s remarks earlier today rang the bell with me. So what I am about to say are not the words of bitterness but disappointment. I have spent the major part of my life either working on or advising yacht and ship owners here in the states and overseas and out of necessity I have grown a thick skin along the way. The older I get the more important time becomes so if I go to the trouble of offering information that I have learned with my own hands and eyes or have taken from those with more experience than I it is important that at least its considered and not buried in a shower of BS. I have found that all too frequently more and more of these threads become fly swatting contests and we all know what attracts flies. For me such a distracting environment becomes too much effort for too little yield . The Stainless Steel Fastener thread comes to mind. It’s like a bucket of muddy water— there is some good solid information in the bucket but it’s heavier and is laying on the bottom. Those who want or need this information have to be able to filter and go to the work of dredging it out. If you lack experience and you really want to learn the effort can be tedious and fraught with misdirection. If you are new and looking for answers it is not easy figuring out who knows what.. Those who have read my few posts know I call them as I see them and if this runs cross grain to somebody I tend to favor insight and experience over decorum and hope I don’t offend somebody. I do however feel bad for those new wooden boat owners that innocently get sucked into following bad advice and soon find themselves and their familys overwhelmed and struggling just to get out on the water safely in a boat of their dreams and hard work.

Google has made everyone an expert these days and this site is a very good example. I wish I had an answer for this condition but I don’t —it’s the human condition I guess and so with a few key strokes anybody can feel authoritative and not have to deal with the consequences of such behavior. How cushy it is. And it’s not just the neophytes, there are some frequent old time posters on this site that continuously offer bogus advice and because this is a chat room more than a library it often gets tacked to the mast with all the weight of a station bill. In my world it’s just me and the hull and if I blow it I get immediate feed back and pay the consequences. Working with risk keeps you honest and humble. I have to tell you that most of the really savvy old time hands I know don’t even have a computer and may have never read a Wooden Boat so there is a major disconnect between today’s information network and the old school shipwrights and boat builders. Those who get published seem to be those who know how to get published. We should all ponder on just about how much old fruit is still hanging on the tree before it gradually falls off to rot and waste. It makes me sad to think how much wood hull wisdom will be lost in just the next decade and conversely how many dilettante expertise books pop up every year and will come to reside on future bookshelves as the answer when honestly many of these authors don’t even understand the question. I never offered my name up on this site for the sole reason that the waterfront is really a small world and the wooden waterfront is even smaller . I have some hard bark on me from years in the marine trades and a sense of humor and demeanor that doesn’t always work well on the internet so the risk of being misconstrued or labeled made this decision easy.

So now I’ve said it— no hard feelings — pass the bottle

Good By and good luck

[Lew Barrett]

I am sorry to read this, as I always read your answers Feazer. You would qualify as one of my...as Peter might say....twenty guys. The fact that you don't always get satisfaction from your considered responses doesn't mean that somebody else hasn't. I've learned a lot from you and would ask you to reconsider. I don't have to ask Bob because I have every confidence he'll be here with good advice for me when I need it. I hope that's right, Bob.

Something I have learned here is
1. When I am wrong, somebody will correct me and in the end that is sometimes more useful than being right ....and.....
2. When I have something useful to offer, it can come back to me (often in odd ways, not necessarily directly through a forum posting in the clear) that somebody found my experience useful.

Being largely self taught, I have some bad habits/wrong headed ideas that sometimes need correction. I have always found it done gently here by my peers, and I think you are one of the people I could learn things from.

Reconsider.