CPES- (clear penetrating epoxy sealant)- uses, and how to make your own…

Discussion in 'Materials' started by hansp77, Jun 6, 2006.

  1. DanishBagger
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    DanishBagger Never Again

    Thanks Michael,

    I _am_ new to epoxies. This project of mine is my first.

    Nice site - I am reading through it right now.


  2. GrouchyOldCoot
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    GrouchyOldCoot Opinionated Old Fart

    Wow - An Intelligent Boater


    Dude where have you been? I have been looking for an intelligent person with a logical mind, such as yourself, on any of the internet boat forums since I joined. Finally a ray of light!:D

    Now I realize the info comes from WEST and they have a vested interest in selling their epoxy BUT damn it makes perfect sense.

    How can CPES be doing anything if allows water penetration? Its just lightly epoxy coating some percentage of the individual wood fibers (and not 100%)

    Now I also understand that full epoxy coating of wood may trap moisture already inside the board and thus cause rot from within and yes if the epoxy coating is penetrated (crack, gouge, etc) the same could happen, but if CPES is letting in that much water, it really is not doing much. I have not read the info on your site yet, but I am headed off in that direction!

    There has to be something in-between CPES saturation and total epoxy encapsulation of wood? (Just like there must be something better suited to bottom bedding than 3M 5200 – which is a whole other debate!):rolleyes:
    Joined: Nov 2004
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    BOATMIK Deeply flawed human being

    Howdy Grouchy Coot,

    If CPES allows the water content of the timber to go up to 40%.

    And good quality epoxy systems allow the water content to go up to 8 to 10%

    Then you are after a material that allows the water in the timber to reach 20%

    Given that rot can start to be a problem over the low teens...

    I wouldn't recommend your desired approach :)

    The above is the downside of a logical mind!

    The other way to deal with the rot problem is the way the old time designers did it. Take huge pains over ventilation and drainage and things like protecting end grain. Epoxy coating allows any old chump to build a long lasting virtually rot proof boat.

    I have spent much of my life maintaining other people's boats - and it is the last thing I want to do with my own. So I epoxy coat and it cuts the maintenance by a very large amount. With the price of paint and varnish these days (the marine ones are more expensive per litre than the epoxy - it is probably true of gallons too) by the time the boat is two or three years old I am starting to pull ahead of the game on financial grounds - and so far ahead on labour that there is no comparison.

    Most of this is because the epoxy simply stops the moisture from getting in so the wood doesn't "move" - so joins, plugged screwholes and the like don't crack the paint - which is when the deterioration starts. Actually I prefer to use no nails or screws at all for just this reason.

    Best Wishes to All
    Michael Storer
  4. GrouchyOldCoot
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    GrouchyOldCoot Opinionated Old Fart

    Thanks for the valuable experience.
  5. Aquamagi
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    Aquamagi Junior Member

    Boat builder

    Paul Oman who posts on "epoxyproducts.com" says that xylene is a good thinner to make the epoxy penetrate. I would really like to get a clear statement on this. Does anyone know.

    Hans A.
  6. Ramona
    Joined: Feb 2007
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    Ramona Senior Member

    I simply use methylated spirits to thin. Up to about 40%. Also use metho to clean brushes.
  7. PAR
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    PAR Yacht Designer/Builder

    Aquamagi and Ramona, there's no debate here and this is a well discussed, tested and debated subject on a 5 year old thread.

    There is absolutely no reason to thin epoxy with any solvent. If you're cutting epoxy 40% they you are so far off base that you really shouldn't be asking people to pay you for your efforts.

    The bottom line is two fold; first is when you dilute epoxy with a solvent, like denatured alcohol (methylated spirits), you dramatically reduce every aspect of it's physical properties. A 15% dilution with denatured alcohol, will reduce epoxies compressive strength by about 40% and it's tensile and peel strength by 50%, plus it's ability to waterproof (the second point) goes right out the window. You might as well use straight alkyd varnish, which would have a better moisture resistance then epoxy thinned at 40%. At 40% you have bubble gum that doesn't resist moisture and has no meaningful strength.

    In short, thinning, even just a little ruins epoxies ability to do much of anything. The truth about the issue, which has been born out in many tests, is the amount of "penetration" has absolutely no bearing on a coatings ability to waterproof! What all the tests have proven is, it's the quality of the coating, not the amount it penetrated the substrate that matters.

    Lastly, unless you have a chemical understanding of what you're doing to a molecule when you screw around with it's formulation, you're just guessing. Clearly anyone using a reactive dilutant like denatured alcohol or xylene hasn't the foggiest idea what they're doing. There are a few ways to effectively reduce the viscosity of epoxy, for substrate penetration, wetout or what ever, but solvents aren't the way folks. The most commonly employed technique is called the hot on hot method, but you can also use a non-reactive modifier in the formulation if desired, though again, you have to have a clue about the molecule you're screwing with.

    I hate to be so harsh, but I just can't believe people are still doing this. Epoxy is nothing like polyester or vinylester resin systems. These resins you can "play with" using solvents and all sorts of stuff, but epoxy is a wholly different animal and shouldn't be treated like the poly's.
  8. fg1inc

    fg1inc Guest

    Thanks Par.....again! I just don't understand why people continually want to take an incredibly good product and render it useless.
  9. Stumble
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    Stumble Senior Member

    I think people want to try and thin epoxy for a couple of pretty reasonable intentions, but without really understanding what it is.

    First they look at the cost of decent epoxys, then at the way encapsulating is applied, and think, well this is like painting, so why shouldn't I be able to thin it like paint?

    Of course the reason is that EPOXY IS NOT PAINT. It is a highly engineered product that requires precision in working with, and very tight controls to maintain its properties. Plus the fact that the 'penetrating epoxy' market has somehow fooled people into believing that the thinner the epoxy is the better it enter the wood. While it would be nice to get epoxy deeper, the fact remains that the viscosity of the epoxy has almost no effect on how deepely into wood it penetrates.
  10. PAR
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    PAR Yacht Designer/Builder

    This isn't correct. The lower the viscosity, the deeper the penetration into a porous substrate (like wood). Temperature and non-reactive modifiers are the usual methods to reduce viscosity. Some epoxy formulations have less viscosity (the non-reactive modifiers thingie), such as Raka. Others can be heated quite a bit and still offer reasonable working times, such as West System extra slow 209, which can be easily taken to 100 degrees and you still have 30 minutes working time (45 minutes at 95 degrees). I have a proprietary formulation that's even better and can tolerate 110 degrees for 30 minutes (45 minutes at 100 and about an hour at 95). At these temperatures the epoxy is thinner then water and sucks into wood like a sponge. If the wood is hot (and cooling) when you apply the goo, it penetrates even further. This is the hot on hot method.

    Agreed Stumble, the penetrating epoxy market has been whipped up by good advertising hype. I know people who swear by these products, but then again they don't get to repair and/or disassemble this things 5 years later to find the net result of these snake oil sales. For the most part repairer/restorers have realized what's going on and have backed off using these products, if not entirely, quite substantially. I very rarely find a need for thinned epoxy, though every once and a while I have a use for it. I made a reusable gasket out of thinned epoxy, the last time I made some up. I know the chemistry very well and have my own recipe, that doesn't do nearly as much damage to the physical properties, as most of the major formulations do (Smith's is a 37% cut, for example).
  11. ondarvr
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    ondarvr Senior Member

    Thinning polyester and VE does about the same thing as in epoxy, you end up reducing just about every physical property. They become less water, UV and crack resistant in the best cases, some solvents will inhibit the cure dramatically and leave you with junk. The % range of monomer for best physical properties can be very narrow in some formulas and it's not wide in any of them.
  12. spenance
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    spenance Junior Member

    Do not thin epoxies. Are are CPES and WEST compatable as a team?

    I feel like I'm beating a dead horse here.
    But want to add my experence with this.
    Way back when I was in boat building school I had a wonderful old teacher that told me to never screw with products weather it be paint, epoxy, Dolphinite, or 3M5200. He said these product manufactures have paid chemist, testers, etc to develop there products to be the best as is and no one should ever screw with altering what they have worked so hard to perfect. Never compromise on materials and strive to be the best as can be as a boat builder and crafstman and you will always keep a good reputation.
    I ran my own business since the early 80's and lived true to this belief. I never thinned epoxy and have used Smith's as solely a primer for paint and varnish.
    I will admit I did concoct a "sealer" that I used mostly for varnished teak, swim platforns that cosisted of 1/3 lidseed oil, 1/3 turpintine, 1/3 Peddit high build. Longgevity at least doubled some lasted 3 years on swim platforms.
    In the 30+ years of building and restoring boats I started with pumping out as many west system bottoms as we could. it seemed to be the answer to all the boat owners with old leaky bottoms. After 20 years many of these bottoms started falling apart and we did much learning what we did wrong.
    Now we build many more traditional bottoms, a combo of, West in the laminations, 5200 in the traditional joints, cpes in the wood surface to make an excelent bond wood to paint and varnish. The point of it all is that there are excelent products strait out of "The Can" that each do there job very well and there is no product out there that "Does It All".
    We used very little "thinners" (No one wanted to breath this stuff). Positive air masks are highly recomended or industrial disease will result.
    We found it more cost effective to use products as is, not wast time to mixing and thining and cleaning brushes was a large cost to the customer we could do with out.
    My main question to you all would be (Perhaps this should be a new thread)
    When useing CPES as a "Primer" for a coat of WEST epoxy. How compatable are the two together as a team? At times these products need to work and blend together and these two need to be compatable.
    I have always wondered if any of the 2 companies or independant testing have been done?
  13. PAR
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    PAR Yacht Designer/Builder

    CPES and West are compatible, but you have to ask yourself a simple question. What's the difference in peel strength between the two, on the same substrate? If you apply a penetrating epoxy to a substrate first, then apply an epoxy over it, the bond is totally (okay mostly) dependent on the peel strength of the penetrating epoxy's grip on the wood. This is the big butt kicker of perpetrating epoxies, particularly Smith brothers.

    Independent testing has shown that penetrating epoxies are mostly marketing hype. In fact the major brand, has been involved with a number of law suits over the advertised claims, they say it can do. In fact, they had to change their name to reflect these law suit conclusions.

    Most of the penetrating epoxy formulators, now are focusing their products as a bond promoter, which is dubious at best, but as yet uncontested, mostly because the testing data can go both ways.

    Simply put, penetrating formulations are effective only in a few instances and these instances, can be easily be out performed by more conventional techniques. In short, there are reasons to use a thinned epoxy, but not in the concentrations typically seen, by the major players (some exceptions are notable). Particularly dense hardwoods can benefit from a very light "cut", before finishing, but there are other techniques that work better.
  14. Roly
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    Roly Senior Member

    G'day Paul, hope this finds you & family well.
    A quick question for you.
    How do barrier coats (as in Interlux 2000) work if they are so loaded with solvent?
    Never could get my head around that, so I flow coated (at 0.5kg /m2) 100% epoxy on
    with boat upside down. Gotta get conditions right for that. Fast hardener & 25deg C. Came out like a mirror!
    Then, hi-build, epoxy primer two grades, "barrier coat", International tie coat primer & finally International 900 series 2 Pac.
    Phew! Just finished, came out pretty good.
    Ok for new build, but not the sort of option available to most repaints.

  15. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Epoxy paint, though using all or part of the epoxy molecule, isn't the same thing as the goo we use to attach cloth with. Don't get confused with the marketing BS. Epoxy is a big selling point for some products and if just part of the molecule is in the formulation, you can call it epoxy. This is how single part paints get away with it, like "Easyposy". It's not really an epoxy, but does have some elements in it. 2 part paints can be real epoxies, but also need to do more then the typical laminating resins we use, so it has fillers, pigments and/or dies and lots of other stuff, some of which are solvents to lower viscosity, elongation modulus, etc. and increase profit margin (solvents are cheaper than resin).

    Using a straight epoxy is a great barrier coat and something I do fairly regularly. I'll usually do the first coat straight and the second with some filler, so final smoothing (it should already be fair) has something to eat into, without affecting the barrier coat.

    How you been Roly?
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