Preview: How to Use Epoxy, Part 3 – Sheathing Wood with Fiberglass and Dynel

27 Responses So Far to “How to Use Epoxy, Part 3 – Sheathing Wood with Fiberglass and Dynel”

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  michael huynh says:

  You mentioned that if you use peel ply after applying the filler coat of epoxy, you wont need to do very much sanding at all. What is the goal of sanding the filler coat of epoxy?

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    Eric Blake says:

    The goal would be to smooth the surface to prep it for paint. Epoxy alone has very little UV protection and will degrade over time if un protected. Paint or good exterior varnish has UV protection in them, and will protect the epoxy.
    Best, Eric

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  Thomas Graves says:

  Thanks for the great videos!
  What is the roller cover that you are using?

  Thanks!

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    Nate Rooks says:

    Hi Thomas – those yellow foam roller covers are solvent-resistant and come in a few different sizes, usually 1/8″ or 3/16″ nap and 3″, 7″, or 9″ widths. Here’s an example:
    https://shop.hamiltonmarine.com/products/roller-cover-foam-7–solvent-resistant-3-16–nap–2-pack–15090.html

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  Don Silsbe says:

  I am currently building a boat with a 3/4” square keel strip. I was thinking about sheathing just this strip with Dynel, to protect the wood from boat ramp abrasion. Good idea? Bad idea?

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  Terri Whittaker says:

  Good day. Planning on doing the bottom of a 16 ft. plywood dory, which is presently painted. Should I sand to roughen the painted surface or try to remove ALL paint? Also how many coats of resin do I need to apply? As you can probably tell…a real newbie here.

  Thanks

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    Nate Rooks says:

    Terri – yes, you should remove ALL the paint. Otherwise the epoxy and fiberglass will only adhere as well as the paint, which is to say… not very well. Yes, it’s one of the worst jobs, but it will be worth it in the end.

    If you watch our new series “Mastering Epoxy with Russell Brown,” you’ll learn more about glassing and how much epoxy to use: https://www.offcenterharbor.com/videos/mastering-epoxy-russell-brown-part-7-fiberglass-outside-hull/

    The basics are: one coat of epoxy when applying the fiberglass (part 7, linked above), another thickened coat as the “fill coat” (to be released soon), and then a final gloss coat before painting.

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  Mark Nowlan says:

  I’m loving these videos…so worth the subscription!

  Question though…i’d read or seen before (apologize but can’t find the reference) that it was a good idea to have already coated/primed the surface before the fabric is applied. Kind of in line with what Eric’s saying here in that he didn’t like putting fabric on wet surfaces…but i was of the understanding that you’d have let the prime coat of epoxy cure before fabric is applied? is this just saving a step? would you have rather have coated/cured and then fabric but did it this way for demonstration purposes?

  appreciate any feedback.

  tsk

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    Robert Collier says:

    Terrific videos. After over 50 years of using epoxy & fiberglass while building 3 sailboats, I still have learned so much—thank you. These videos are priceless! Some of the techniques I have learned by trial and error, but these videos would have been a god-send if they were available several decades ago. Your many articles are contributing so much valuable information to the boat building community. Again, thank you—
    Bob Collier, Dana Point, California

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  Doug Heisler says:

  Eric, Terrific series but I don’t understand one point: when you are demonstrating the 1208 biaxial cloth you say the woven mat side goes to the “cosmetic side” and the chopped strand mat side of the 1208 goes on the outside. I am adding a layer of 1208 to the the bottom of a flat-bottom skiff. Does the cosmetic side refer to the existing bottom of the skiff or to the finished 1208? i.e. do I lay the woven mat side against the bottom of the skiff? or do I put the chopped mat side against the bottom of the skiff? – I will also be using Peel Ply, Thanks, Doug

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  Konstantinos Lekkas says:

  Hi Eric. I have a rather stupid question since I am new at this. But let say you need on a deck or on the hull to make fiberglass repairs. Can you use multiple layers of fiberglass? Is there a limitation to the number or something else I need to take under consideration?

  Thank you

  P.S. I am super excited for the rigging series as well as this one. Keep the boat craft DIY videos coming please!!!!

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    Konstantinos Lekkas says:

    Also was wandering. Can you use Dynel over your fiberglassed deck as an non skid surface? From the videos it looks like it would be just the thing

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  Steve Buck says:

  I would like to see more information on outgassing. What is it, what effect does it have on wood/epoxy/fiberglass composites, how to minimize the effect?

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    Eric Blake says:

    Steve,
    The only outgassing I am familiar with is caused by the temperature of the wood rising before th eepoxy cures, creating bubbles on a clear coat or bubbles under cloth. Typically this is from direct sun coming through a window and heating up an area. We try and cover all of the windows in the shop that would allow this to happen, and try and be sure the temperature in the room isn’t rising when we are doing any epoxy work.

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  Björn Nilsson Thafvelin says:

  Hi
  Where do you buy Dynel? We try to get it here in sweden

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    Eric Blake says:

    Hey Bjorn,
    I get it from the stock room at the boatyard. A quick search online should turn up a few sources. Defender Marine used to be the only place you could buy it but it is available at many more places now.

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  John Nelson says:

  I plan to add glass cloth and epoxy resin to the bottom and sides of a 16ft wooden, flat bottom boat (marine plywood). The angle of the sides to the bottom is pretty high (80+ -ish degrees). I’m planning on glassing the boat one half at a time (from the keel out/up to the rails). I’m guessing I’ll need to glass the sides separately from the bottom as the excess cloth towards the bow seem like too much to scrunch together. Does it make sense to use a heavier cloth on the bottom and a light cloth on the sides? Will the heavier cloth wrap around a softened 80 degrees corner? Any tips on how to overlap cloth to minimize bulk (and sanding), but maintain structural support? From the videos, it does not look like the Dynel is suitable for the bottom due to the texture, correct? Any advice is appreciated. Excellent videos. Love the peel and paint part. Thx

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    Eric Blake says:

    Hey John,
    It really comes down to how you tailor the cloth. Heavy on the bottom is good but you could also just do a second layer of the same cloth you are sheathing with so you don’t need to source two different materials. Dynel can work just like any other fabric, you just need to fill the weave with additional coats. Any overlap in cloth I tend not to go less than 1″ but the a decent size overlap especially along the chine isn’t a bad idea.

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  Jonathan Mc Donald says:

  I always like your videos. They are so informative. What do you clean your squeegee off with?

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    Eric Blake says:

    Hey Jonathan,
    We have boxes of clean white rags that we use a lot. You can just swipe it across the edge of a paint tray as well, if you are talking about getting excess of during the process. Otherwise wait until the epoxy cures and it pops off the next day like it was never there.

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  Paul Atkins says:

  Eric, I work alone often, and with time constraints and I need to get the second weave-filling coat on after it has cured. Not ideal it seems. Do you have any advice?

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    Eric Blake says:

    Hey Paul,
    The low blush 207 hardener we are using here doesn’t require any sanding or additional prep for up to three days after it has been applied. After that you would want to wash the surface with warm water and scotch brite before applying additional coats, to remove any amine blush that epoxy’s all develop once fully cured.

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  Steve Brookman says:

  Great info. I’ve been epoxying for years and now know that I’ve only been doing it partly right! Now on to #4….

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  Raymond Hurley says:

  Should mention out-gassing particularly when applying fabric to a real wood structure such as strip planking; less of a problem with plywood.

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    Eric Blake says:

    Hey Raymond,
    You make a good point. Thirsty woods such as cedars will off gas, I find we have the most problem with a rising temperature in the shop, and sun coming through the windows and heating up specific areas of the part. Best practice to apply cloth if finished clear with a constant or falling temperature, and pull the shades on the windows!

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  J.D. Bondy says:

  Great stuff, Eric. When rating fabrics such as “8 oz fiberglass”, I assume the 8 oz refers to the weight of a certain area of fabric so you can compare weights of different fabrics. Can you give more specifics on what that terminology means?

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    Eric Blake says:

    Hey JD
    Good question. Typically it refers to oz/ square yard of cloth.