Epoxy squeeze-out: removal

Discussion in 'Wooden Boat Building and Restoration' started by NoEyeDeer, Sep 6, 2014.

  1. NoEyeDeer
    Joined: Jun 2010
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    NoEyeDeer Senior Member

    Ok, so I'm facing the dreaded cured solid epoxy clean-up time. This is all the squeeze out that I couldn't get to while the boat was upside down on the strongback.

    I already know the approved method is to wave a heat gun around until the epoxy starts cooking, and then scrape away. I'm a bit concerned about using this method due to the lightness of the construction on the boat in question.

    Heat doesn't just soften epoxy. It also softens wood (which is how steam bending works). The planking on this boat is 3mm ply, which means the face veneer is only 1mm. No margin for error. Also, I'm a tad worried that the amount of heatgunning required to soften the epoxy could result in heat transfer into the glued laps, etc since the thermal mass of the (small) structural elements is quite low. This would not be good.

    Brainwave: since I'm only wanting to remove fairly small blobs and beads along lap lines, etc I only need to heat small volumes of pox. So, how about using a soldering iron? This would produce heat right where I want it, with pinpoint accuracy, and should mean effectively zero heat going where I don't want it.

    Has anyone ever tried this? Can anyone see any potential disasters?
     
  2. NoEyeDeer
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    NoEyeDeer Senior Member

    Hmm, ok. I just remembered I have a hot melt glue gun, which generates similar temperatures to a soldering iron (which I don't currently have). So, I figured I should experiment.

    Pulled the glue stick out, heated the gun up to operating temperature, wiped all the old melted crap off the end of the gun so it was just clean metal. Then, got a paint scraper ready and applied the tip of the gun to a bead of cured squeeze out.

    It works. :D Just held the tip of the gun on the bead for a few seconds and the epoxy in that small area softens enough to let go of the timber with no damage and no apparent residue. The timber right next to it is still stone cold. I think this is a winner. It wont be a fast procedure, but it'll be clean and easy. Will make a more concerted effort tomorrow and see how it goes.
     
  3. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    Well there you go then! The old saying "necessity is the mother of invention" rings true again.
     
  4. NoEyeDeer
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    NoEyeDeer Senior Member

    Gave this idea a pretty good run yesterday. Some observations are:

    The hot melt glue gun works well, except that its tip is too bulky for some areas and it doesn't generate enough heat to deal with bigger blobs quickly.

    So, I bought a basic 80 watt soldering iron and gave that a run, in combination with a 2" (50 mm) stainless steel paint putty knife. This is very good if use with care. If not used with care, the tip of the soldering iron will burn the timber.

    There is an optimum temperature where the epoxy softens just enough to let go of the timber cleanly, but without breaking down the epoxy too much. This is what you want to aim at because it gives the cleanest results. At its best, the result is as good as if there had never been any squeeze out at all. It looks perfect.

    The best technique I found was to use the tip of the soldering iron on top of the putty knife blade, close to the leading edge and just outside the bead of rock hard poop. This enabled me to slide the knife along the poop slowly, with light to firm pressure and without forcing it, and peel it off nicely. The area of the putty knife blade dissipates the heat from the soldering iron to the point where the blade wont burn the timber, but is still hot enough to deal with small beads of poop quickly. Bigger blobs take a bit more time, and sometimes it helps to touch the iron directly to the bigger blobs to cook them up fast.

    Anyway, after all that I have had another brainwave. What I am going to try is getting a scrap of knife blade and welding that to one of the tips that came with the soldering iron. The cunning plan here is to take a two-handed job and turn it into a one-handed job. It might even work. If it doesn't, I can still use the two-handed method.
     
  5. messabout
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    messabout Senior Member

    The Berz-O-Matic torch people have an option that includes a flame that heats the knife at whatever temperature that is dialed in. This is one of the accessory options that that the manufacturer offers. It is marketed mainly as a paint stripper. It might very well function as an epoxy skimmer. I never thought of that as an option. Good option in case of need.

    It seems to me that eliminating the blobs in the first place would be the most preferable method. When, at the time, the epoxy is exuded from the clamped joint it can be easily wiped away with lacquer thinner or acetone on a rag. Timing, of course, is essential.
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Heat the blade on a multi tool (torch) and run the multi tool on the lowest vibration setting . . .
     
  7. NoEyeDeer
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    NoEyeDeer Senior Member

    Well hey, that had just never occurred to me at all.

    This is to deal with the stuff I couldn't get to when the boat was upside down on the strongback, with clamps and temporary bracing and everything else in the way while the epoxy was still semi-solid. Obviously I clean it up before it cures when I can. Sometimes this is not possible.

    A lot of the time you don't even need acetone or thinner on a rag. All you need is a standard putty knife, assuming the surface is going to be painted anyway and a bit of pox in the pores is not an issue.

    I've also found that sometimes it is better to wait until the epoxy is semi-cured (still a bit rubbery) and then take it off with a sharp chisel. This leaves a clean surface (if done properly) and can be a lot less trouble than trying to clean up uncured epoxy when there are clamps and whatnot all over the place. I sometimes use this for jobs where the glue line is not going to be under stress during the build. Glue the thing up, get rid of all the clamps after 12-15 hours, then do a clean up with the chisel. Rubbery bits come off cleanly, without smearing and dripping everywhere.


    Don't have one. ;)
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Pick one up, you'll get spoiled pretty quickly. Pick up a good one, as the cheap ones don't have any nuts.
     
  9. Westfield 11
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    Westfield 11 Senior Member

    Does that mean that they are screwed instead?
     
  10. NoEyeDeer
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    NoEyeDeer Senior Member

    Not if they don't have any nuts. :D
     
  11. PAR
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    PAR Yacht Designer/Builder

    Yep, pretty much, unless you employ an "appliance" . . . :)
     
  12. Wayne Grabow
    Joined: Aug 2003
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    Wayne Grabow Senior Member

    "This is all the squeeze out that I couldn't get to while the boat was upside down on the strongback."

    "Well hey, that had just never occurred to me at all."

    Thanks for the humor. Can't say you didn't try to explain the situation.
     
  13. messabout
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    messabout Senior Member

    N-E-D, I was not impugning your intelligence or craftsmanship when I suggested cleaning the blobs before it hardens.

    I have created a few kilograms of blobs myself, especially in places inaccessible at the time.
     
  14. NoEyeDeer
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    NoEyeDeer Senior Member

    You are welcome to impugn my craftmanship. I know where all the dodgey bits are. :D
     

  15. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    There always seem to be a few hard to get at bits of gunge left when building upside down. I try and protect as much as possible with masking tape and poly sheet if I can, especially to stop sticking to frames and formers. Worth it on build too when peeling off after half set, can save a lot of time later.

    The multi tool I have was a boon for removing half the transom (internal solid) off a Mirror a year or so back. Would have taken ages with just a 1" chisel and hammer, done in 40 minutes. Buy a good one, then you will swear by and not at it. Not sure what brands you have, but I went for the Fein one which has taken all the abuse I have given it well. Briliant for chopping into FRP hulls with holes in (done by owner or collision) and preparing the repair surfaces as well as sanding glass reinforcements prior to gelcoat etc.

    Yup, slicing with a sharp chisel is a good way of getting the worst of any errant lumps off. Note the diagonal action gets best results, though I'm sure your familiar. The fillers are the killer for knocking the edge off though so keep the stone handy.
     
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