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

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

  1. hansp77
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    To severely edit Steve's extensive (and great) elaboration, I guess this is one bit of information that we might be interested in (that is if we still want to try this sort of thing ourselves).
    There seems to be a lot of reasons why making it yourself can go wrong. And Steve provides some good reasons why his product being based on natural wood resins is superior.
    However, if some random-mix of solvents and some random-made epoxy can work to our favour, then this is the mix that we are after.
    Our job is to find out what mix of solvent and what mix of epoxy will work.
    It may not replace the real stuff for every job, but it certainly could for a lot of jobs. Not every job or purpose requires the best of the best.
    To borrow a term that Pashbe1 tought me, this might equate to 'guilding the lilly' (polishing the turd).
    So it would seem to me at this point that we could take as a good example of solvents the ones on the list that Roly provided (I can't seem to find any other examples of ingredient lists.)
    The solvents in order of highest percentage to lowest are

    Aromatic Naphtha
    xylene (common paint store solvent)
    toluene (common paint store solvent)
    isopropyl alcohol (2-propanol) (common, cheap rubbing alcohol)

    an example of a mix we might try is

    30% Aromatic Naphtha
    25% xylene
    20% toluene
    15% isopropyl alcohol (2-propanol)

    as far as the epoxy mix to use, I would have to open this up to suggestions.

    What would be better, something like a 50:50 mix epoxy, or something like a 5:1? why, and what is the difference here?

    I don't know.
    It makes sense that a slow hardener is what we would be after, so as to allow the maximum penetration and evaporation of solvents.

    I think that this can be done.
    For starters, if a few of us who are still game can get these solvents (aromatic Naptha seems to be the one we might have to order) and try a mix with the particular brands of epoxy that we already have, then we can report the results and hopefull find some that work and some that may not.

    Of course we will have to devise some tests.
    Steve mentioned the test of mixing the thinned epoxy with water, to see if it will de-mix.
    Of course we will have to use some real CPES throughout the same tests, to see what sort of results we are after.

    Now I should say at this point that I have never actually used Steves CPES product.


    What I have used is international evidure, and epiglass wood preserving epoxy.
    I guess these are some of the products that Steve is reffering to when he says that

    "The mechanical properties of the resin system of CPES is an almost
    exact match to the mechanical properties of natural wood.

    No other epoxy can make that statement."

    Now I and others have been pretty happy with these products, so, even if our DIY does not match CPES, then it may at least come close to some of these other products. And still, at a fraction of the price.
    Last edited: Jun 16, 2006
  2. Texas Boater
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    Texas Boater Member

    The Best Thing Since Sliced Bread?

    I have read all of the arguments from both sides of the CPES debate and done some research myself and the only thing I question is that when I contacted "Epoxy Manufacturers" that do not market a CPES-like product. as to why they were not in the market and if I could use their epoxy but thinned to achieve the same thing, they all said the same things: 1)They did not believe the "CPES" claims of being the same as the original wood and 2)Highly thinned epoxy was not as good a water seal as slight reduced viscosity epoxy (via slight thinning or warming of the wood) or non-thinned epoxy. :(

    If CPES was actually a wonderful as the sales-pitch says it is why are there no major competitors? Through recorded business history, anything that has such a strong market share and price structure as CPES, also has competitors and imitators! Also why is this copyrighted and patented (?) miracle cure sold under so many names: Smith&Co CPES, MultiWoodPrime, Lingu, RotDoctor CPES, LiquidWood? Why not just CPES, worldwide?:confused:

    I will probably end up using Steve’s product myself since it is so highly recommended by Don Danenberg, but it just appears that “marketing” is also one of the strengths of this product. I have to agree that keeping one type of epoxy and a couple of solvents around your shop makes a lot more $ense that multiple epoxies, solvents, sealers, fungicides, etc…:)
  3. Thin water
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    Thin water Senior Member

    Be carefull of the isopropyl alcohol (2-propanol) (common, cheap rubbing alcohol) bought at your local drug store as it contains a lot of water. This is why it says 70% or even as low as 60% in the discount stores. If water causes the seperation of resins this would be bad. Gasoline additives labeled "Water remover" and "Gas line antifreeze" are often pure isopropyl alcohol (read the bottles to get the correct chemical). Just don't buy a lot of this stuff at once or they will think you are using it to cook meth with :)
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  4. Roly
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    Roly Senior Member

    I agree!
    Depending what your primary use requirements are, I personally wouldn't bother trying to reproduce CPES. More cost effective to just buy the one that has already had the R&D done on it.
    If your boat is that rotted you think CPES is gonna fix it, well , good luck.

    IMHO, you are way better off replacing the compromised timbers and using heated regular epoxy. (For a sealer)
    Or, diy thinned epoxy with an unthinned overtop as soon as the solvent has blown off.

    CPES really comes into its own in non-marine applications. As in,where you
    are not concerned with gaining original strength of the member you are trying to rejuvenate. Just preserving and densifying.

    If I was hell bent on an optimum DIY penetrating epoxy I think the base should have a cycloaliphatic hardner as a start. It is more moisture tolerant
    and therefore less likely to be compromised before the mixture cures.
    Also I would mix the resin and hardner, let sit until warming then add your
    solvent concoction and apply.

    CPES-If I could, I would buy it; For the limited uses I have for it.
    I can't,so I mix my own, "gut feel brew" ;)
    Paul has a good rational on epoxies. Url below.

    Same with acetone. Can contain water! Same with all water miscible substances.

    Time to shut up, I'm repeating meself!
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  5. hansp77
    Joined: Mar 2006
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    My intention here is to try to come up with the best possible way to make our own penetrating epoxy. Not to replace CPES.

    It seems there are a fare few people that are doing this already- probably some that are doing it well, and definately some that are doing it badly.
    Sure there are some problems involved, and for most people and the serious jobs, spending the extra money to simply buy the real stuff is probably well worth it.

    However, clearly there is enough interest for some people, for some jobs, to mix up their own.
    This is not necessarily about fixing a boat that is 'that rotten,' though for some people it could be (cheaply get a few more seasons out of it maybe?), but just about fitting the treatment to the job.

    I hardly percieve this taking even a small dent out of the market share of CPES and other penetrating epoxies.
    After all, it is probably pretty much only the people that are already doing this- with laquer thinner, acetone, or a random 'gut feel' mix of solvents- that will continue doing this. (It just means that we can be doing it better).

    For some jobs, CPES and other expensive products are certainly overkill and unwarrented.
    But for these same jobs, if we could flood the job with cheap homemade stuff, then why not?
    Whether it be a cheap dingy or tender to tie up under a jetty, or play boat for the kids, or getting another season or two out of a rotting deck before replacing the whole thing. The best product, is not always the best solution.

    Now to the specifics.
    Isopropol with water in it is a bit of a problem, (I think- chemists correct me if I am wrong here)
    so if this is what we need, then care will have to be taken to find the purest stuff. As far as I know, most alchohols even when called 100% are still only around 95%, I don't know the chemistry exactly, but that last 5% is very hard to get out- fractional distilation or something. Something we definately don't want to do.

    However creating anhydrous solvent (or drying our solvents) is very very easy.
    All one needs is common epson salts, dried in the oven for a couple of hours, then powdered.
    Then you fill a coffee filter with it, and filter your solvent through it. Acetone, toluene, and the likes.
    The salts will suck out the H2O from the solvent.

    To use the powdered epson salts again, just air evap the solvent, then oven dry again just before you use it.


    Well reaonably easy.
    Once the solvent mix was figured out, all we would have to do is to dry the solvents, then mix to the proportions we want, and seal up a big bottle of it, and store it in the shed untill needed.
    Once it is sealed, it will not get wet again.
    Then it is only a matter of mixing whatever type and brand of epoxy proves best (cycloaliphatic hardner maybe) and then splashing in a bit of your pre-prepared and mixed solvent.
  6. Texas Boater
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    Texas Boater Member

    What is the point?

    And the point of all this?

    It seems like we are going to great lengths to make a moderate substitute for a product that already exists, and by what I read does a fine job, only so that we can say we did it ourselves and maybe save a few bucks.

    It doesn't make sense and there does not seem to be any value added in all the risk.

    I would hate to read how some member of this forum blew himself up because he didn't wait long enough before reusing his epson salts and tried to dry then in his gas oven.:(
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  7. hansp77
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    Come on, seriously,

    anyone that is likely to blow themselves up from putting wet solvent in an oven probably shouldn't be getting on a boat in the first place, let alone trying to fix one.

    The point is

    people are currently thinning their own epoxy. Thus already taking risks.

    thinning your own epoxy could work well, or it could work badly. The aim is to work out the best method so that people that are going to do it, do it the best way possible.

    "we" if you are included, are going to "great lengths" simply to have more control of the processes and products available to us.

    If I had a need to use a penetrating epoxy on an integral peice of my boat then I would use the best stuff that money can buy.

    If however I want to smother a tender that I have built myself in a penetrating epoxy, of less than marine quality wood, that will only be used for paddling from a jetty to my swing mooring, then my own home made one will do me fine.

    As to how moderate the substitute will be, well that is the whole point of this excercise.
    To make it as good as possible.
    All of these products, if you believe every blurb, are each and everyone the best thing on the planet.
    We already know that fungicide in penetrating epoxy degrades the quality and causes problems. There are penetrating epoxies on the market that still use fungicides. Thus, a simple, well designed home made one could very well be better than some of the 'real' products on the market.

    The excuse to save a few bucks, can sound pretty desperate.
    But then- why do any work yourself on your boat, or learn any specialist skills, instead of just paying the experts?
    Welding is not for everyone, nor is epoxying, nor painting, nor building or drying ones own solvent. Everysingle thing you can do on or to a boat has its risks and dangers if you do it wrong. But if anyone inclined wishes to take the time, and has the ability, then any of them can be learned.

    As I have said, this is not aimed to be a process to replace a product, but rather to provide the information and techniques for people who are interested and have a use of it, to make their own.
    Or more to the point, make their own in a better way than they have previously done so.

  8. bilgeboy
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    bilgeboy Senior Member

    Give me a break, Ivan. How much is 'saying you did it yourself' worth? Hard to put a number on that, isn't it?

    I couldn't agree with Hans any more.

    This is one of the best threads going on the site. Granted, we are not organic chemists, but certainly no one is going to blow themselves up experimenting with homemade penetrating epoxy.

    I do much "dumber" stuff every day- like driving over the speed limit.

    Your attitude, Ivan, is certainly not one of the cutting edge innovator. The exploration of the unknown is what drove naval expeditions from the beginning, and I believe is so deeply rooted in the psyche of the true sailor, that to remove this would rob him of any sense of adventure and (I cringe to use the word) romance. I encourage Hans to keep trying. He may find something better. Way cheaper is better, but so is a better product. He is never going to put Steve out of business.

    Sure do appreciate your input, Steve. I read your post once, missed the part where you told us how to thin epoxy well, but I'll read through it again.

  9. hansp77
    Joined: Mar 2006
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    You know I think I missed that part too:confused:
    Not that I blame Steve,
    In fact I commend him for even entering into this discussion.
    At least for our sake he did drop the reference that while everything could and should go wrong, it just might maybe occasional not...;)

    Thanks for your support.
  10. Roly
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    Roly Senior Member

    Don't bother with the toluene, it aint water soluble. You should be able to separate by taking the top level off.
    Heat it at your own risk.....(tri-nitrotoluene---TNT):D
    BTW.. Everybody knows that all these solvents are not good for your respiratory system, right? I had to get out a manufacturing business in polyesters owing to styrene.

    This one of the redeeming features of epoxy 100% solids;No styrene monomer.
    Then we want to load it up with toxic solvents?
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  11. Grouchy Old Coo
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    Grouchy Old Coo Opinionated Old Fart

    No Place for a Texan

    Texas - Obviously these boys think they are a heap smarter than Steve Smith or any of the other chemists that work at countless epoxy companies. And they won't be happy until they have micro managed this subject to death, developed the most expensive poor performing CPES take off they can and either ruined a boat or hurt someone.

    I'd say its time to stand down and let these boys play.:p
  12. hansp77
    Joined: Mar 2006
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    :p :p :p

    Anyone would think we were talking about brewing up out own bird flue vacine in the bath tub :p

    Well 'boys' I would say it might be time to let the 'men' stand in line and purchase their product.
    Then I remembered that we have never tried to get 'them' out of that line :eek:

    I really do welcome constructive criticism Grumpy, without it this thread would have gotten no where.
    (oh and welcome to this forum- you might want to beware of micro-managing though :p :p :p it is pretty dangerous for stuff like that here- PEOPLE here generally like to TALK about things that they are going to DO- strange as that may seem)

    But to even address the things that you have said in very first post here would break one very cardinal rule... (thanks stonebreaker)
    A rule that I think I may have already broken.

    Attached Files:

    Joined: Nov 2004
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    BOATMIK Deeply flawed human being

    If Penetrating epoxies don't stop water getting back into the wood - what are they acheiving?

    This is from the WEST site. It shows that timber can get up to serious levels of moisture content if Penetrating Epoxies are "protecting" the timber.

    Note the much lower moisture content of the samples coated with WEST.

    Other High Solids Epoxies (High Solids means almost no solvents in the mix) will also outperform the Penetrating Epoxies.


    The penetrating epoxies allow the moisture content go up to 40% - you can expect the rot to continue.

    The problem is that when all that solvent evaporates out of the epoxy matrix it leaves big holes that the smaller water molecules use to access the timber underneath.

    Penetrating epoxy was the best technology in its time - but things have moved on.

    Best Regards to All
    Michael Storer
  14. DanishBagger
    Joined: Feb 2006
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    DanishBagger Never Again

    Ah, nice one, Boatmik - that eases my mind, as I decided early on to simply use "proper" epoxy and UV lacquer. No CPES.

    Joined: Nov 2004
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    BOATMIK Deeply flawed human being

    Howdy 'Bagger,

    There I have put together some of the information I have written over the years on

    If you are new to epoxies there might be some helpful stuff there that will save money and time.

    Best Regards
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