Some Paint Advice

Discussion in 'Fiberglass and Composite Boat Building' started by fallguy, Dec 30, 2019.

  1. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    We painted Epifanes 2 part poly two coats last week using roll and tip.

    We rolled with 7" x 1/8"nap rollers using a thinner rate of 10% which is Epifanes max.

    We tipped with a cut in half the long way foam roller 9" wide.

    The lines left by the roller modified to a tipper failed to lay down well.

    Our atmosphere was a bit cool; like 65F; the humidity was about 54% which we drove up for tacking off cleanly without static buildup.

    I am driving the heat up to 75F or a 10 degree pickup. And considering going avove manufacturers thinner rate from 10 to 15%.

    Any advice appreciated. We sanded it all flat with 220 then 320 and are trying again tomorrow.
     
  2. BrissoDamo
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    BrissoDamo Junior Member

    2pac pu always spraying, this is why they do pre painted paneling
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    2 part PU will brush OK, but you need brushing thinner.
     
  4. fallguy
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    fallguy Senior Member

    We use brushing thinner at 10%, but we are taking it to 15% tomorrow.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    That's a bit of a jump, 10 to 15%.
     
  6. BrissoDamo
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    BrissoDamo Junior Member

    stroke the run line?
     
  7. BrissoDamo
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    BrissoDamo Junior Member

    is it flat or vertical?
     
  8. missinginaction
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    missinginaction Senior Member

    No way should you go to 15%. I use Interlux Perfection all the time (essentially the same product) and use far less brushing thinner than the max. I think your problem is that you tipped with a roller. I get what you tried to do but that method is going to leave lines. Get a good China bristle brush for your tipping and have the guy tipping work right along behind you. One of the biggest mistakes I've seen people make with 2 part LPU's is overthinning. At the 65 degree temp you mention I typically use about 5% and at higher temperatures use less. In the upper 80's I use a splash to none at all. Rollers can also be a problem. I had a supplier for good rollers a few years back. Then, suddenly the rollers started to fall apart as I was using them. Turned out the manufacturer changed the adhesive. I now use Wooster 1/8" nap rollers.
     
  9. fallguy
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    fallguy Senior Member

  10. fallguy
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    fallguy Senior Member

    we had solvent pop at lower thinner rates; it was frightening to watch; think a thousand fish eyes per sq ft

    think it was the environment; probably was 20%rh in the testing area
     
  11. Blueknarr
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    Blueknarr Senior Member

    FG

    The humidity is high. Especially, with the lowish temperature. Poly has issues with water and humidity. Should be below 50%. Close to 40% is even better.
    Why the heavy t"ween coat grit?
    What problem are you trying to fix?
     
  12. missinginaction
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    missinginaction Senior Member

    You mention fish eyes. That makes me think of surface contamination or incompatibility between the finish coat and the surface. You are using the manufacturers recommended primer, right?

    I've seen fish eyes when someone forgot to check and puts down an epoxy prime coat over some cured resin that had blushed a bit. I've never seen it with a 2 part LPU that went down over it's recommended primer.
     
    Last edited: Dec 31, 2019
  13. Blueknarr
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    Blueknarr Senior Member

    Ditto to Missinginaction!!
    15% reducer will be way to much. You will be trading roller tracks for sag lines.
    What did you tack with? Unfortunately, some tack clothes cause fisheye! I don't trust them and now use untreated washed microfiber towels.
    You driving up rh suggests an issue with tack clothes.
     
    missinginaction likes this.
  14. Blueknarr
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    Blueknarr Senior Member

    I don't have the screen resolution to see either roller tracks or fisheyes. If you have thousands of eyes\square foot, then you have a serious adhesion problem and the whole coat needs to be removed. It is the fail point. It will sloph off taking any overcoat with it. Like paint on top of masking tape.
     

  15. fallguy
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    fallguy Senior Member

    There were no fish eyes! Solvent pop. Look it up.

    I explained the heavy 'tween coat' was the only way to cut down the lines left from the paint not flowing out.

    stop with the fish eyes; good heavens, I need advice; not misdirections

    solvent pop is when the paint skins over before thinners flash; this happened at lower thinner rates of 5%
     
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