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epoxy thickening and coating question?

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  • smithriverranger
    3 questions: 1. Is wood flour ok for thickening epoxy to use as a glue? or is silica a better choice? 2. I m planning on building with mdo......Do i need to
    Message 1 of 6 , Mar 31, 2004
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      3 questions:

      1. Is wood flour ok for thickening epoxy to use as a glue? or is
      silica a better choice?

      2. I'm planning on building with mdo......Do i need to precoat the
      endgrain before i actually wet out the end let it tack and then add
      the thickened epoxy? Or can i do it all at once? Seems easier to not
      have to scrub the blush and from i what i have read i'm under the
      impression that it will be a stronger bond if i do it all at
      once...both a chemical and physical bond.

      3. If i have precoated wood with epoxy and it has fully set can i
      use gorilla glue to bond the 2 epoxy coated surfaces together? I'm
      real familiar with the gorilla glue plus it's much cheaper than
      epoxy so i'm tempted to use it in some circumstances.

      Epoxy is new to me, i've only built with titebond II and gorilla
      glue in the past. Longetivity is my goal here so a little over kill
      is ok by me.

      Thanks,
      Jason Stancil
    • Jeff
      Wood flour is a great filler for gluing. Silica would work but sands harder than the wood flour. I ve use a lot of wood flour in the past but have switched
      Message 2 of 6 , Mar 31, 2004
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        Wood flour is a great filler for gluing. Silica would work but sands harder than the wood flour. I've use a lot of wood flour in the past but have switched to Talc. It's relatively cheap, mixes easy, sands well, and can be found anywhere. Baby powder is pure Talc with Fragrance.

        Building the Sneakeasy as made my garage smelling like a new born baby. The local discount stores have the 22 oz sizes for $1.79. Just make sure you get the pure talc versions instead of the corn starch. I haven't noticed that the fragrance added to the Talc makes any difference but it sure is nice to work around!

        Always pre-coat end grain regardless of what your doing. If gluing, it'll stop the end grain from wicking away epoxy and creating a starved joint, and it needs to be pre-coat to water proof. The end grain always soaks up a fair amount of epoxy.

        Any time I'm planning on putting extra coats of epoxy on, I always try to add another coat before the previous sets to much. I always use the finger print rule. If you can still leave your thumb print in the epoxy but it's not excessively tacky, that's the perfect time to put on another coat. You can get by for around 24 hours but sometimes the blush can set on over night. Usually you can pull it off every 4 - 6 hours.

        I use RAKA epoxy at about $40.00 gallon and a 16 oz. bottle of Polyurethane is $10.00 or almost double the cost of Raka epoxy. I really like the Elmer's Polyurethane equivalent of the Gorilla glue and use it anywhere I have to glue a none critical item and can leave the fasteners in place. It's just so much more convenient and less hassle than epoxy but certainly not cheaper.

        Jeff

        ----- Original Message -----
        From: smithriverranger
        To: bolger@yahoogroups.com
        Sent: Wednesday, March 31, 2004 3:16 PM
        Subject: [bolger] epoxy thickening and coating question?


        3 questions:

        1. Is wood flour ok for thickening epoxy to use as a glue? or is
        silica a better choice?

        2. I'm planning on building with mdo......Do i need to precoat the
        endgrain before i actually wet out the end let it tack and then add
        the thickened epoxy? Or can i do it all at once? Seems easier to not
        have to scrub the blush and from i what i have read i'm under the
        impression that it will be a stronger bond if i do it all at
        once...both a chemical and physical bond.

        3. If i have precoated wood with epoxy and it has fully set can i
        use gorilla glue to bond the 2 epoxy coated surfaces together? I'm
        real familiar with the gorilla glue plus it's much cheaper than
        epoxy so i'm tempted to use it in some circumstances.

        Epoxy is new to me, i've only built with titebond II and gorilla
        glue in the past. Longetivity is my goal here so a little over kill
        is ok by me.

        Thanks,
        Jason Stancil




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      • cha62759@traverse.com
        Hi Jason, two answers: 1. Silica is better but clean up immediately. You will have a real time sanding it. If you are gluing uncoated surfaces use microfibers,
        Message 3 of 6 , Mar 31, 2004
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          Hi Jason, two answers:
          1. Silica is better but clean up immediately. You will have a real
          time sanding it. If you are gluing uncoated surfaces use microfibers,
          they prevent starved joints.

          2. When you are ready to glue uncoated surfaces, wet out first let it
          sit a while then use epoxy thickened with microfibers. As long as you
          are adding epoxy to not fully cured epoxy you don't need to worry
          about amine blush. A chemical bond is stronger than a mechanical bond.
          Try to do it all at once but be careful of starved joints.

          3. I don't know the answer to this one but I would avoid mixing
          systems and in critical applicatins I would absolutely avoid mixing
          systems. I'm not sure Gorilla glue is all that much cheaper but is
          easier to handle sometimes. I would only use Gorilla glue on bare wood
          joints.
          Bob Chamberland

          In bolger@yahoogroups.com, "smithriverranger" <jasonstancil@h...> wrote:
          > 3 questions:
          >
          > 1. Is wood flour ok for thickening epoxy to use as a glue? or is
          > silica a better choice?
          >
          > 2. I'm planning on building with mdo......Do i need to precoat the
          > endgrain before i actually wet out the end let it tack and then add
          > the thickened epoxy? Or can i do it all at once? Seems easier to not
          > have to scrub the blush and from i what i have read i'm under the
          > impression that it will be a stronger bond if i do it all at
          > once...both a chemical and physical bond.
          >
          > 3. If i have precoated wood with epoxy and it has fully set can i
          > use gorilla glue to bond the 2 epoxy coated surfaces together? I'm
          > real familiar with the gorilla glue plus it's much cheaper than
          > epoxy so i'm tempted to use it in some circumstances.
          >
          > Epoxy is new to me, i've only built with titebond II and gorilla
          > glue in the past. Longetivity is my goal here so a little over kill
          > is ok by me.
          >
          > Thanks,
          > Jason Stancil
        • John ONeill
          If you don t already have one, I highly recommend buying System 3 s starter kit for $10. It only has enough epoxy to play around with, but it comes with an
          Message 4 of 6 , Apr 1, 2004
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            If you don't already have one, I highly recommend buying System 3's
            starter kit for $10. It only has enough epoxy to play around with,
            but it comes with an easy to udnerstand book, thickeners, measureing
            cups, I think they even put gloves in it. It'll get you up to speed
            quickly and give you an idea what the stuff'll do and how to do it.

            My experience is that while there is a learning curve, epoxy is
            easier than you might think. Even the drawbacks, like long set-up
            time, can be used to advantage and turned into plusses. 'Plastic'
            epoxy, kicking but not cured, is easy to work. The stuff is
            incredibly versitle, glue, filler, fairing compound, undercoat for
            varnish . . . you can color it, sand it, even use it as a bearing
            surface. Both of my 5 year old Cartopper's stainless steel
            centerboard pins are loosly embedded in clear epoxy. They're as
            tightly fitted as the day they were made, no give, but still spin in
            their holes (solidly embedding ss in epoxy promotes crevace
            corrosion). I cured the epoxy right around the pins, which were
            coated with wax.

            My gut reaction is that Gorilla glue over cured epoxy might not be a
            good idea, but I don't know. However, I think once you start using
            epoxy the question of using Gorilla glue over it won't be an issue.

            Some pros won't use epoxy, as a glue, even over cured epoxy. If they
            have to they'll sand through the old coat and glue-up fresh wood to
            fresh wood. Think ahead and it probably won't be a significant issue.

            John O'Neill

            --- In bolger@yahoogroups.com, "smithriverranger" <jasonstancil@h...>
            wrote:
            > 3 questions:
            >
            > 1. Is wood flour ok for thickening epoxy to use as a glue? or is
            > silica a better choice?
            >
            > 2. I'm planning on building with mdo......Do i need to precoat the
            > endgrain before i actually wet out the end let it tack and then add
            > the thickened epoxy? Or can i do it all at once? Seems easier to
            not
            > have to scrub the blush and from i what i have read i'm under the
            > impression that it will be a stronger bond if i do it all at
            > once...both a chemical and physical bond.
            >
            > 3. If i have precoated wood with epoxy and it has fully set can i
            > use gorilla glue to bond the 2 epoxy coated surfaces together? I'm
            > real familiar with the gorilla glue plus it's much cheaper than
            > epoxy so i'm tempted to use it in some circumstances.
            >
            > Epoxy is new to me, i've only built with titebond II and gorilla
            > glue in the past. Longetivity is my goal here so a little over kill
            > is ok by me.
            >
            > Thanks,
            > Jason Stancil
          • Paul Lefebvre
            I met a guy in Puerto Rico in February who is building a catamaran that has a stripped lower hull and ply uppers. He taught me a new trick - when he ripped his
            Message 5 of 6 , Apr 1, 2004
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              I met a guy in Puerto Rico in February who is building a catamaran that has
              a stripped lower hull and ply uppers. He taught me a new trick - when he
              ripped his strips he saved the sawdust, then put it through his wife's food
              processor to make his own 'wood flour' - I saw some of it, looks just like
              the stuff Raka sells, perfectly even and very fine, only in his case the
              color matches his wood perfectly....

              Paul Lefebvre


              >>.... If you use sawdust, try to figure out a way to use only the really
              finest stuff.
              The particle size really seems to affect the handling properties of the
              epoxy mix.
            • Lincoln Ross
              ... Works fine. I still like to add a little silica as it makes the stuff behave a little better. But wood flour alone is not bad. Probably much better than
              Message 6 of 6 , Apr 1, 2004
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                See below:

                >Jason Stancil wrote:
                >3 questions:
                >
                >1. Is wood flour ok for thickening epoxy to use as a glue? or is
                >silica a better choice?
                >
                Works fine. I still like to add a little silica as it makes the stuff
                behave a little better. But wood flour alone is not bad. Probably much
                better than silica if you end up breathing a little bit of it. Sometimes
                I will hold my breath while adding the silica until I walk outdoors with
                it to do my mixing. A really good mask may be better. If you use
                sawdust, try to figure out a way to use only the really finest stuff.
                The particle size really seems to affect the handling properties of the
                epoxy mix.

                >2. I'm planning on building with mdo......Do i need to precoat the
                >endgrain before i actually wet out the end let it tack and then add
                >the thickened epoxy?
                >
                I think I would coat once, wait five or 10 minutes, and come back. And
                if it works with your building sequence you could come back in a while
                (like 30 minutes) and add the thickened epoxy. You may be worrying a bit
                much here. Probably depends on just where the end will be in the
                finished boat.

                >Or can i do it all at once? Seems easier to not
                >have to scrub the blush and from i what i have read i'm under the
                >impression that it will be a stronger bond if i do it all at
                >once...both a chemical and physical bond.
                >
                People say it will still be a strong bond if you come back the next day.
                Blush comes off easily, tho I guess the water might take a while to dry
                out of the end grain. You shouldn't be depending on good strength from
                end grain butt joints. That only works, as far as I know, with very
                precise joints with Titebond in very light balsa. Not something you'd
                see on a boat.

                >
                >3. If i have precoated wood with epoxy and it has fully set can i
                >use gorilla glue to bond the 2 epoxy coated surfaces together? I'm
                >real familiar with the gorilla glue plus it's much cheaper than
                >epoxy so i'm tempted to use it in some circumstances.
                >
                You'd better sand that epoxy. Haven't tried it myself. Any Gorilla Glue
                I've seen is MUCH more expensive than epoxy bought in bulk. Try raka.com

                >
                >Epoxy is new to me, i've only built with titebond II and gorilla
                >glue in the past. Longetivity is my goal here so a little over kill
                >is ok by me.
                >
                Just be careful not to get it on you! (you can clean your tools with
                vinegar, but don't let the stuff get on you)

                >
                >Thanks,
                >Jason Stancil
                >
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