Penetrating Epoxy kicked off

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  • jstafford
    Senior Member
    • Jun 2018
    • 157

    Penetrating Epoxy kicked off

    Had my first go with penetrating epoxy last night and it did not go as planned. I was using Jamestown Dist 2 part system. Measured very carefully and tried to move quickly. First I noticed my cup was getting warm, then came the smoke and then bam I had Jello. Checked my watch and it had been 12 minutes since I had stirred. The boat is wrapped so it was very warm. I think I got the 2-1 ratio correct. Should I use less hardener next time? Is it that temp sensitive? I'm guessing I did not get much penetration.
  • DeniseO30
    Thinks too much..
    • Jan 2009
    • 4674

    #2
    Epoxy needs to be exact measured not like polyester resin.

    mixing in a cup will almost guarantee it will kick way faster than necessary, as soon as you mix it transfer it to a shallow container.

    If you're working time and kick times can't overlap, look for a slower hardener not using less or more hardener.
    Denise, Bristol PA, retired from HVAC business, & boat restoration and building

    Comment

    • David G
      Senior Member
      • Dec 2003
      • 89688

      #3
      Re: Penetrating Epoxy kicked off

      This is confusing. Can you share a link to the specific product you used?
      David G
      Harbor Woodworks
      https://www.facebook.com/HarborWoodworks/

      "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

      Comment

      • Ian McColgin
        Senior Member
        • Apr 1999
        • 51639

        #4
        Re: Penetrating Epoxy kicked off

        Epoxies can go wildly, frighteningly, exothermic if mixed in a hot environment, if the pot is left in sunlight, and if the volume is the pot makes it essentially self-cooking. The easiest cure is to mix much smaller batches and spread it fast. A volume sitting around in a pot for twelve minutes is eight to ten minutes too long.

        Do not deviate from the mix ratio. That's not your problem.

        Comment

        • stromborg
          Senior Member
          • Sep 2010
          • 6319

          #5
          Re: Penetrating Epoxy kicked off

          Don't mess with the mix ratio.

          Yes, epoxy is heat sensitive and will set faster when warm, it also generates heat as it sets up so trying to keep it in a "cup" will lead to setting faster. Penetrating epoxy, eh? I'm guessing you are spreading it over a large surface. Pouring the mixed epoxy into a shallow pan helps. Or you could try pouring it out of your mixing cup onto the boat and smearing it around from there.

          I use System3 and have found it helpful to have their fast and slow hardeners on hand, once my shop goes from the usual mid-60s into the 70s I switch to the slow stuff. I don't know if there is a slow setting penetrating epoxy for use in warmer temperatures.
          Steve

          If you would have a good boat, be a good guy when you build her - honest, careful, patient, strong.
          H.A. Calahan

          Comment

          • Canoeyawl
            .
            • Jun 2003
            • 37698

            #6
            Re: Penetrating Epoxy kicked off

            The first dumpster fire I ever saw was caused by an apprentice mixing up a pint of epoxy in a quart jar. It quickly became to hot fot him to hold and started smoking. He was frightened and tossed it in the dumpster. Then it went off!!
            The trick for large amounts is to make it up in smaller batches and immediately spread it out onto a sheet of plastic film. Spread out thin like that you could get maybe an hour of work time. (West System has three different speeds of hardener)

            Comment

            • jstafford
              Senior Member
              • Jun 2018
              • 157

              #7
              Re: Penetrating Epoxy kicked off

              Does the pump set-up help with mixing up really small batches? Last night I only mixed up to the smallest markings on the mixing cup(maybe an ounce) they had sent me and ended up throwing half of that away. Sounds like I need a process for really small batches. Hopefully it also cools off a bit.

              Comment

              • bnaboatbuilder
                Senior Member
                • Jan 2013
                • 140

                #8
                Re: Penetrating Epoxy kicked off

                Purchase an inexpensive kitchen scale to measure by weight for small batches. Really only needed when mixing less than 3oz of equivalent volume though for 2:1 ratios. 3oz volume or more in marked cups is easy with pumps.

                Pouring the mixed epoxy into a wide flat tupperware container spreads it out and helps reduce the heat build up. Also any leftover cured epoxy in the plastic container will just pop out to reuse the container.
                Last edited by bnaboatbuilder; 09-18-2018, 10:03 AM.
                - John

                Comment

                • SailAR
                  Member
                  • Dec 2016
                  • 68

                  #9
                  Re: Penetrating Epoxy kicked off

                  ice bath

                  Comment

                  • Ian McColgin
                    Senior Member
                    • Apr 1999
                    • 51639

                    #10
                    Re: Penetrating Epoxy kicked off

                    For epoxies that don't have pumps and for batches too small for even the smallest pump, I mark small cups or even clear tubes used like a pipette. One for resin, one for catalyst, third wider for mixing. Fast, easy, accurate. Especially with a penetrating sealer like CPES, you don't need to worry about such things as getting it all down in one go.

                    Comment

                    • Tom Christie
                      Commercial Mariner
                      • Mar 2015
                      • 273

                      #11
                      Re: Penetrating Epoxy kicked off

                      Originally posted by jstafford
                      Does the pump set-up help with mixing up really small batches? Last night I only mixed up to the smallest markings on the mixing cup(maybe an ounce) they had sent me and ended up throwing half of that away. Sounds like I need a process for really small batches. Hopefully it also cools off a bit.
                      Check your measuring cups for accuracy.
                      Use water and an accurate measure from a kitchen measuring cup to check.
                      I have found some inaccuracies in my disposable measuring cups, adjusted and have had no problems measuring epoxy by volume.
                      Other than thorough mixing, measuring is the most important variable when working with epoxy.
                      I wouldn't wait for the weather to cool down, just get some "slower" ( higher temp ) hardener.

                      Comment

                      • David G
                        Senior Member
                        • Dec 2003
                        • 89688

                        #12
                        Re: Penetrating Epoxy kicked off

                        As always... reading the instructions helps. West System kindly makes all sorts of instructional info available as a free download. Use it. I esp. recommend "... on Boat Construction" for a comprehensive reference. At our shop, we call it 'the epoxy bible'.

                        The home of WEST SYSTEM marine-grade epoxy resins and hardeners for boat building, boat repair, home repair, and restoration.
                        David G
                        Harbor Woodworks
                        https://www.facebook.com/HarborWoodworks/

                        "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

                        Comment

                        • jstafford
                          Senior Member
                          • Jun 2018
                          • 157

                          #13
                          Re: Penetrating Epoxy kicked off

                          Forgot I took a couple pics. This is after it kicked off. I started off at the 1 mark.20180917_185710.jpg20180917_185648.jpg

                          Comment

                          • Arlc
                            Senior Member
                            • Oct 2017
                            • 285

                            #14
                            Re: Penetrating Epoxy kicked off

                            I use a $15 digital scale minus the tare weight of a disposable cup to mix epoxy by the gram. Accurate with any volume.
                            Why does anybody use the crude measurements of pumps and dispenser cups for mixing epoxy?

                            Comment

                            • Tom Christie
                              Commercial Mariner
                              • Mar 2015
                              • 273

                              #15
                              Re: Penetrating Epoxy kicked off

                              Originally posted by Arlc
                              I use a $15 digital scale minus the tare weight of a disposable cup to mix epoxy by the gram. Accurate with any volume.
                              Why does anybody use the crude measurements of pumps and dispenser cups for mixing epoxy?
                              Because I need a container to mix in anyway, why not measure it out in the same container, checked and calibrated for accuracy and with no problems.
                              That's why.
                              No need for a $15 dollar scale, that could fail.
                              But to each their own, carry on.

                              Comment

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