Polyester resin drying?

Discussion in 'Materials' started by jawnn, Aug 17, 2015.

  1. PAR
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    PAR Yacht Designer/Builder

    CDX is literally the lowest grade of plywood available. Again, every Lowe's/Depot in the country has real "Exterior" grade plywood. The labels are usually stamped on the surface and also on the end grain, which can be read while it's stacked on a pallet. CDX has no place on a boat. Yep, eating plywood adhesives is bad for you, though with a little garlic, not too bad really. Sand the polyester a bit, before the epoxy goes on, to insure good adhesion. Use a fair coarse grit (60 or less). 3 gallons of epoxy will cover a lot of sheets of plywood.
     
  2. SamSam
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    SamSam Senior Member

    This isn't a boat.
    If it was mine, I'd be tempted to put a bunch of latex paint over it to seal off the **** you already put on it, cover it with some cheap carpet and see what happens. It doesn't sound like it's worth putting too much effort or money into it.
     
  3. PAR
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    PAR Yacht Designer/Builder

    Oops, though CDX is still crap. I too would simply take the easy way out and seal it up with some go and toss some carpet over or something.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Chipboard is rubbish, but so is gypsum wallboard. Both disintegrate on contact with water.
     
  5. PAR
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    PAR Yacht Designer/Builder

    CDX is an exterior exposure 1 grade, with a lousy good face and the other side much worse. It has minimum veneer count, lots of voids, defects and patches throughout the panel. It's common to see overlapping veneers and other sins with these panels and they're only rated for static loading.
     
  6. jawnn
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    jawnn jawnn

    I am going to a different lumber yard tomorrow, and they will be glad to sell me something more expensive... but ai do not need a better surface, I can fill the voids with epoxy.....I need to show them the label that you posted.
     
  7. jawnn
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    jawnn jawnn

    OK I got the cheaper CDX looks ok to me.

    I need to know if the epoxy has any difficulty in drying?

    I have one piece of wood that has a slightly tacky feel from the penetrating epoxy... maybe I did not mix it well enough?

    Does the epoxy need to be kept above 60 degrees?

    And how much of the Ospho residue needs to come off?
     
  8. gonzo
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    gonzo Senior Member

    Penetrating epoxy has a lot of solvents and is not a really good product. Depending on the formulation, it will need different minimum temperature to cure; check the label. Also, some epoxies will chemically bond with moisture more than others, which may prevent them from curing in high humidity conditions.
    Where is the Ospho on?
     
  9. jawnn
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    jawnn jawnn

    The Ospho is on what is left of my metal sub-floor. And it looks like I will have to remove some of it at least the waxy part. actually it is impossible to scrub off all of it. the rust really ruffed up the metal.

    The rains have returned so I will have to epoxy in sealed room with wood heat.....hope it is not explosive fumes. better to keep one window open.

    I should get the epoxy today. Hope it has instructions on the label.


     
  10. SamSam
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    SamSam Senior Member

    I am imaging a school bus, as I've had a few. The 'sub-floor' is the metal frame of the bus, and that supports the ply. I can't see any reason at all to wonder whether epoxy will react to ospho coated metal. Just screw or bolt the ply to the metal. Why epoxy is even involved in this project to begin with is a wonderment, but the floor has to be screwed or bolted to the frame, the only concern with epoxy should be whether it will put out toxic fumes inside the bus.
     
  11. jawnn
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    jawnn jawnn

    I am sure it will put out toxic fumes until it is dry to the touch... but there is no other way to keep the floor from rusting away completely.

    there is not enough metal to screw the ply wood to. I will have to glue it in place with the epoxy. Oh the misery of this project.....any one else would just take it to the recyclers....


     
  12. jawnn
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    jawnn jawnn

    how exacting does the measure of the epoxy have to be... I went a little over the with the resin and tryed to adjust for the hardener....probably a bit less hardener than I should have put in.... will this dry? or am I screwed again.

    I may just finish the top of the ply wood with Varathane....I am getting sick tiered of camping out in a tent. the rains have returned with a vengeance.
     
  13. gonzo
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    gonzo Senior Member

    Epoxies are a two part system that is very sensitive to mix ratio. The "hardener" is not like for polyester where more makes it cure faster. Too much hardener will stay liquid in the mix and the result will be soft and rubbery. The same is there is too little, some resin will stay liquid.
     
  14. PAR
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    PAR Yacht Designer/Builder

    Most epoxies can tolerate some misalignment of the ratio, but is depends largely on the mix ratio and which one you screwed up. For example, if it's a 1:1 mix and you're off by a bit, you'll likely be fine, but if it's a 3:1 or a 5:1 and you screwed the hardener amount, the amount you messed up with is a multiple of the ratio, so you're off by 3 or 5 to 1 on the hardener side.

    In the end, time will tell, but generally, you want to use pumps if you're a novice at this sort of thing or at least graduated containers. Guessing or eyeballing at chemical ratios, will usually just piss you off.
     

  15. jawnn
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    jawnn jawnn

    the thing I am worrying about now is fumes after the epoxy cures....well if I can't small it , I hope it is not going to be bad enough to hurt me ...????? I am going to have to use the varathane on top of some of the ply wood, even cover the epoxy with it....


    but I keep getting a bit of stick from a small patch where I covered the polyester resin with epoxy....may have to grind it off.....

    this project is driving me nuts! and I ran out of plywood and money so I had to use a piece of stand board, covered with epoxy both sides.
     
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