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Re: [Cedar Strip Canoes] fiberglassing

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  • J. R. Sloan
    ... the hull such that it is an extension of the hull, not a protrusion, which means that the fiberglass should lay over it without much difficulty. 2.
    Message 1 of 13 , Apr 8, 2007
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      --- In cedarstripcanoes@yahoogroups.com, charles.k.scott@... wrote:
      >
      > --- You wrote:
      > >Thanks Corky
      > Can you tell me how is the glass laid upto or over the stem ,Do you
      > trim the glass to the very tips of the stem or fold them both over
      > slightly .
      >
      > Mike
      > --- end of quote ---
      >
      > Mike, two things: 1. The outer stem is pretty typically faired into
      the hull such that it is an extension of the hull, not a protrusion,
      which means that the fiberglass should lay over it without much
      difficulty. 2. Several of the websites I've culled through show how
      the outer hull fiberglass is laid up, they do slit the part that lays
      over the bow and stern curves, then trim that such that it follows
      the curve of the hull line, but overlaps by 3 inches or so on both
      sides. The bump this creates when the resin cures is eventually
      filled in with successive coats of resin with some sanding in
      between. If it's not possible to manage that, then the long edge
      should overlap the short edge. The short edge is still long enough
      to overlap, or fold all the way over the leading edge and lay on the
      opposite side, but the long edge should then overlap it, which will
      hold it down.
      >
      > The same thing happens with the interior fiberglassing, again ably
      demonstrated on John Michne's website.
      >
      > Speaking of fiberglassing, there are several schools of thought
      regarding the process. Some folks recommend coating the hull with a
      coat of resin and letting that partially cure prior to laying on the
      blanket of fiberglass. Then the fiberglass is laid on and coated
      with resin which then bonds to the first coat. But timing is
      critical here. If you do not apply the fiberglass within the proper
      time, the sealer coat will cure to the point where the fiberglass
      will not properly bond to it. But attempt to lay on the fiberglass
      too soon and you could run into problems with the fiberglass sticking
      to it. Leave it to cure for too long, and you will have to resand
      the entire hull to give the next coat something to bond to. But a
      chemical bond may be achieved by laying on the fiberglass before the
      sealer coat has fully cured. This is as opposed to a mechanical
      bond, which is achieved by roughing up the first coat to give the
      next coat something to grip.
      >
      > Some folks say it's just too much trouble to seal the hull prior to
      fiberglassing and recommend laying the fiberglass on the bare hull
      and then just applying the resin to bond the fiberglass directly to
      the hull. That does work, no question, but there are issues. The
      resin can wick into the wood, especially if you have some fairly
      porous cedar, pulling the resin away from the fiberglass and leaving
      it white rather than transparent.
      >
      > But either way works.
      >
      > Finally, I've noticed from ads in "The Wooden Boat" that there is a
      vendor advertising really thin resin that wets out the fiberglass
      well. That's important for the first coat, you want it to wet out
      quickly so you can apply it to the entire project before things start
      curing. It is not important that the weave be filled with the first
      coat. The thing that needs to happen is for the fiberglass to bond
      properly to the cedar. The later coats can be thicker, or more
      viscous so that they fill the weave to make the outer shell smoooooth.
      >
      > But I'm not sure I want to be the pioneer who tries it when there
      are plenty of systems that basically do the same thing and are well
      proven. But I won't be there for several months so I have plenty of
      time to think about it.
      >
      > If you have the time and the days lined up, you can do all the
      coating without any sanding, if you use a resin that doesn't cure for
      24 hours or so. But check with the manufacturer to be sure and
      remember, the hotter it is in the shop or wherever the project is,
      the faster the resin cures.
      >
      > Finally, from accidental experience, the blessing of fiberglass is
      that almost any mistake can be fixed with lots of sanding and
      application of a patch. With further coats of resin and maybe
      another thin layer of fiberglass you can fill in almost any gouge
      such that it blends in seamlessly with the original fiberglass.
      >
      > But beware, some are allergic to the particles of fiberglass and
      especially to the cleaners such as Acetone or Laquer Thinner. These
      solvents are extremely toxic so wear a proper mask when using them
      and wear gloves.
      >
      > Corky Scott
      >
      Really great response, Corky!
      JR
    • J. R. Sloan
      ... is that ... stick to ... the fiberglass after the initial sealer coat. The epoxy resin cures to a non tacky touch LONG before it s fully cured. Once
      Message 2 of 13 , Apr 8, 2007
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        --- In cedarstripcanoes@yahoogroups.com, charles.k.scott@... wrote:
        >
        > --- You wrote:
        > One comment to add to Corky's great dissertation.
        > The one problem that concerns me with the partial cure sealer coat
        is that
        > the more un-cured the resin, the more likely the glass cloth with
        stick to
        > it and make it tough to position properly.
        > Alex
        > --- end of quote ---
        >
        > It's actually not very difficult to figure out when you can lay up
        the fiberglass after the initial "sealer" coat. The epoxy resin
        cures to a non tacky touch LONG before it's fully cured. Once it's
        dry enough to touch without it feeling tacky, you can then lay on the
        fiberglass sheet and apply epoxy and the new application of epoxy
        then bonds with the not yet fully cured initial coat, without needing
        to rough that first coat up with sandpaper.
        >
        > It looks like using a slow cure epoxy for the first coat may be a
        good idea here. Another good idea is to discuss this with the
        manufacturer to make sure that the epoxy you intend to use will not
        full cure for 24 hours or so, giving you the window of opportunity to
        lay up the second coat before the first coat is fully cured.
        >
        > This isn't an experimental technique by the way, it's commonly
        used. But it can make for a couple of tiring days.
        >
        > Corky
        >
        At our house, we have the "skeptical spouse" technique for laying out
        fiberglass on fresh hulls. That's when the person who's been telling
        you that you've been making too many piles of sawdust and tracking
        stuff into the kitchen comes out and grabs the other end of the
        fiberglass fabric and helps you lay it out nice and smooth over the
        full length of the hull, and then offers advice on where to cut the
        darts (a sewing term known to persons familiar with power tools that
        have needles instead of blades) so the fabric lays straight.
        Amazing how a project gathers respect when participation by more than
        just one household member is applied.
        JR
      • charles.k.scott@dartmouth.edu
        ... Amazing how a project gathers respect when participation by more than just one household member is applied. ... I have actually asked for help from my
        Message 3 of 13 , Apr 9, 2007
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          --- You wrote:
          Amazing how a project gathers respect when participation by more than
          just one household member is applied.
          --- end of quote ---

          I have actually asked for help from my significant other several times. I needed her to assist with the first couple of strips. Her job was to wipe off excess glue as it squeezed out. Needless to say, she wasn't hugely thrilled to be doing that.

          But she has lately glanced at it and grudgingly remarked that it's looking pretty good at this point.

          Corky Scott
        • Mike Neeb
          Thanks everyone for the input . Last night we epoxyed the stems and keel on ,we ll give it a couple days to cure out and sand every thing back to nice smooth
          Message 4 of 13 , Apr 11, 2007
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            Thanks everyone for the input . Last night we epoxyed the stems and
            keel on ,we'll give it a couple days to cure out and sand every thing
            back to nice smooth lines ,saterday is the big day . we plan to start
            in the morning and go tell its done .
            wish us luck
            Mike

            -- In cedarstripcanoes@yahoogroups.com, charles.k.scott@... wrote:
            >
            > --- You wrote:
            > Amazing how a project gathers respect when participation by more than
            > just one household member is applied.
            > --- end of quote ---
            >
            > I have actually asked for help from my significant other several
            times. I needed her to assist with the first couple of strips. Her
            job was to wipe off excess glue as it squeezed out. Needless to say,
            she wasn't hugely thrilled to be doing that.
            >
            > But she has lately glanced at it and grudgingly remarked that it's
            looking pretty good at this point.
            >
            > Corky Scott
            >
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