white fiberglass sheets from Home Depot?

Discussion in 'Boatbuilding' started by mmelnick, Aug 20, 2010.

  1. apex1

    apex1 Guest


    please tell us how a Epoxy barrier coating would make any sense on a Epoxy coat?

    No, you can´t.
    Just say you missed the point that we are talking Epoxy coating, not polyester, and your first post makes sense to some extend.

    And when you doubt my expertise on that topic, which is allowed, you might learn more in my Gallery (just click my name).;)

    You are the unknown quantity here, not me.
  2. Tim Judge
    Joined: May 2010
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    Location: Hudson River

    Tim Judge Tim J

    Why do they put silica in epoxy barrier coats? To keep water from moving through it.
  3. apex1

    apex1 Guest

    There is no water moving through Epoxy, don´t you get it?
  4. Tim Judge
    Joined: May 2010
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    Location: Hudson River

    Tim Judge Tim J

    "Microplates® in Interprotect 2000E create an overlapping barrier to eliminate any direct path for water migration. Lower emissions formulations available: Interprotect 2000VOC. Interprotect 2000E is now available in 3 gallon packaging to aid efficiencies in the boat yard."
  5. apex1

    apex1 Guest

    On Polyester buddy. On Polyester!

    and you should not buy every sales drivel you read...........
  6. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Whoa.......whoa.....let's take a breath........

    I think that you guys are misunderstanding each other (Richard/Apex and Tim). I've been reading this thread thread and it occurs to me that the coating that mmelnick wants to do on his canoe is pretty similar to the coating that I'm just now finishing up on my decks.

    Mmelnick, I'm restoring a 37 year old Silverton Cruiser just so you understand.

    It seems to me that the barrier coat that Tim is refering to is paint.

    Correct me if I'm wrong here Tim.

    Mmelnick, here's how I've done my decks. This procedure is (I think) in line with what both Apex and Tim are saying.

    1. Once you have your luan ready to go apply 1 or 2 seal coats of epoxy resin. I use a product called System Three Clear Coat for this. Clear Coat is a very thin (read watery) 100% solids resin product.

    2. After the seal coat(s) have cured (you may need more than one coat since different woods can vary in how they absorb the resin) sand them lightly. Just smooth them out, don't go crazy with the sander.

    3. Prepare 4 oz / square yard fiberglass cloth for attachment to the wood. Rather than write a book here I'll leave a link at the end to a resource that discusses how to do this. 4 oz cloth is very light and will add minimal weight but provide some good abrasion resistance and a bit of structual strength. You're not building a freighter, it's a canoe, I think 4 oz cloth would be sufficient.

    4. Once your cloth is ready lay it out on the wood. I mix up some epoxy resin (I use System Three General Purpose Resin, but any decent brand should do) and get ready to attach the fiberglass cloth. I use a squeegie (just like a window washer would use, a 12" wide squeegie with a rubber blade) to spread the epoxy onto the cloth. You want to press the cloth onto the wood and remove almost all of the resin. Done correctly you will see the weave of the cloth after this step is done. Once the glass is attached step back, admire your work and go away while the resin cures. BTW, I always use a medium or slow speed hardener for this step. This gives you time to work, to think and do a nice job. In no case would I use a "fast" hardener here.

    5. The cured cloth and resin will look a bit rough (see the weave?). Now, take a 1/8 inch foam roller and some epoxy resin (again I use general purpose) and roll on a thin coat of resin. Still see the weave? Well then, after the first "fill coat" has cured apply another thin fill coat. If you still see the weave apply a third coat. As a practical matter you'll probably only need two but you never know. Go easy with the roller, roll sloowly and without too much pressure. The idea is to not create too many bubbles in the coat. Oh, don't forget to sand lightly between coats, knock down any bubbles and smooth out any rough spots. You also want to wipe down your surface after each coat is sanded with damp towels and dry it thoroughly.

    I sand between coats with 120 grit paper and do a final sanding with 220. I use a random orbital sander for this job.


    By now you've morphed into a somewhat gooey, fiberglass and epoxy dust encrusted shell of the man you were a few days ago. If you're like me you're crabby because as good as your work looks it's never good enough and there is this little voice in the back of your mind telling you that in spite of all the safety precautions you've taken you've just given yourself a terminal illness.

    But....I digress....it's time to paint!

    6. Your paint is only going to look as good as the surface that you are painting. In other words if you've done all the previous steps well and have been thorough and patient your painting will be a relative breeze. I like to use the two part polyeurethane paints like Interlux Perfection or Awlgrip. My wife say's I like these paints because I'm self destructive and in spite of the numerous safety precautions I take she thinks I'm secretly trying to hasten my own demise (sorry, I digress again). But, many people who I trust have posted here that there are many good paints out there so you can probably use any good quality paint and get good results.

    For the record though I apply two coats of Interlux Epoxy Primecoat per the manufacturers instructions and then two coats of Perfection, again following the manufacturers instructions to the letter.

    There, you're done. Depending on weather conditions this job can take you a week or more from start to finish. Whatever you do be patient, be thorough and think about what you are doing. My advise would be to practice on a small section of scrap ply to get some experience and to build some confidence. Think of it this way, you'll get many years of use out of a boat built right and have pride of ownership. The hours you spend learning proper finishing techniques are the price you have to pay.

    Here's that link I was talking about:


    Download and read "They Epoxy Book". It will help you out.

    All kidding aside, use respirators, chemical resistant gloves and follow all safety precautions, please!

    Good Luck,

  7. Tim Judge
    Joined: May 2010
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    Location: Hudson River

    Tim Judge Tim J

    If the epoxy coating was 100% water proof then no microplates would be needed. Yes polyester (gel coat) allows water to pass through it, so does epoxy, but to a significantly lesser degree. You might want to reference:
    Kotlik, P., Justa, P., and J Zelinger The application of Epoxy Resins for the Consolidation of Porous Stone. Studies in Conservation 28 (1983) 75-79. The addition of certain types of dilutants (agents that reduce cure time...slow hardeners), such as 1,4-butanedioldiglycidyl ether decreases the viscosity of the epoxy and increases its sensetivity to water.
  8. Tim Judge
    Joined: May 2010
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    Location: Hudson River

    Tim Judge Tim J

    Thanks Missinginaction...yes but a barrier coat/primer on the fiberglass with the epoxy resin. This will help prevent moisture from getting to the wood....and making your hull soggy. Apex is right that epoxy is for the most part waterproof.
  9. apex1

    apex1 Guest


    I build in wood epoxy since 35 years, and I do it at the uppermost end of the quality (and price) scale.
    We process several hundred tonnes (metric) of Ep per annum.
    Please stop telling me when the water boils.


    nobody applies a barrier coat on a barrier coat. True?
    Neat poxy resin is a barrier coat. The stuff promoted so violently here therefore completely useless.

    And no, I have not misunderstood that our "expert" here tries to tell a novice that his epoxy surface will have voids and lets water in, no matter how he does it.
    He is just talking nonsense and promoting BS.

  10. apex1

    apex1 Guest

    Thats drivel............

    not one single boat I built got ever soggy, and that have been a few thousand now.
  11. Tim Judge
    Joined: May 2010
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    Location: Hudson River

    Tim Judge Tim J

    Apex...best of luck to you and your business. I mean no harm and no disrespect to you and your expertice.

    Mmelnick...good luck with your boat.

    Missinginaction...thanks for a voice of sanity.
  12. apex1

    apex1 Guest

    over and out......
  13. Steve W
    Joined: Jul 2004
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    Steve W Senior Member

    Apex,youve got that right about the commercially available "barrier coats" being a joke,they are a PAINT and contain solvents which evaporate out as they cure leaving microscopic pinholes hence the need for many coats,we use interprotect on customers boats only because they have already been marketed to and want it ,i stick with 100% solids epoxy resin as a barrier coat on my own boats thank you very much.
  14. mmelnick
    Joined: Jul 2010
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    Location: Colorado

    mmelnick Junior Member

    For me it's more about the money. I just don't see why I would want to spend more money to seal the sealer.

    I'm going to make sure to seal the glass with epoxy, and then it's getting a coat of exterior paint . After all, it's just a canoe that I'll fish from a few days each summer and maybe duck hunt from for a few days in the winter. I doubt it will see more than about a week in the water over the period of a year.

  15. apex1

    apex1 Guest

    More than sufficient for that use! Your coating scheme will last for a long time.

    Good luck, and post some pictures here when done.

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