Paint and Primer in one?

Discussion in 'Materials' started by TwoBirds, Aug 28, 2016.

  1. TwoBirds
    Joined: Aug 2016
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    TwoBirds Junior Member

    Hi

    using exterior paint on a rowboat and all I can seem to find locally are these 2 in ones, are they any good?

    2B
     
  2. ondarvr
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    ondarvr Senior Member

    What's the boat made of.
     
  3. TwoBirds
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    TwoBirds Junior Member

    sorry, it's made of tropical hardwood plywood, bs1088.

    2B
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The paint/primer products are for novices or lazy people and those that think they can by cheap. I've used them (several different brands) and none preformed nearly as well as a regular paint over real primer job. The last brand I used (a Valspar product), peeled off in sheets on previously painted and prepped drywall. Use exterior house paint, preferably "porch and deck" stuff, which seems a little tougher than the others.
     
  5. TwoBirds
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    TwoBirds Junior Member

    Thanks :)

    about what I figured, guess paints are like people, some can do two things at once but neither gets done very well. :)

    2B
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Self priming acrylics perform well. But not with one coat on bare timber.
     
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I've not seen a single brand of "paint/primer" all in one that stuck well to any substrate, especially raw wood. I had some success cutting the all in one about 15%, to get a reasonably peel test, but it was still less than a regular prime and top coat test. I also know of a few contractors, that tried to get away with this stuff on new construction over new drywall and they're eating redo's like crazy, with 1 year old paint jobs peeling off walls.

    I'm pretty sure it's the way they've formulated it. Previously, the primer would have a fairly high silica/mica content for stain blocking and sandability. Now, because they need to insure gloss retention, they're using isoparaffinic solvents to meet lower VOC requirements. In order to meet these low VOC rules, you'd typically increase solids (pigment and binder), but this makes the paint thicker, so they work on just a higher resin content, which is good for spraying, but the reduced pigment content tends to affect shear viscosity.
     
  8. TwoBirds
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    TwoBirds Junior Member

    I'll go with paint over primer, as you may guess from my forum handle the paint +primer would be my choice if I was sure it would preform well.

    I was doing some research and one guide said to use primer with no talc in it, is it a must?

    nobody here has even heard of such a thing.

    2B
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    Neither have I. Talc is a filler, I've not heard of it used in paint, it is usually undercoats that contain fillers, to smooth irregularities. I'd disregard that advice, I think. If you are unsure what the previous paint was, rub it with a cloth soaked in methylated spirit (denatured alcohol ? ), if it softens and comes off on the cloth, it is an acrylic, and best recoated with an acrylic. If not, you can recoat it with either acrylic or an alkyd enamel finish, always following the instructions on the can re primers required.
     
  10. TwoBirds
    Joined: Aug 2016
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    TwoBirds Junior Member

    sorry, it's a new boat, I'm still sanding, and sanding...

    hmm, I did see some primers that said they hide imperfections, maybe they have a filler.

    guess that would be "Filler + Primer" :D

    2B
     

  11. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Primer's adhesion isn't helped by fillers, the filler laden undercoat acts to smooth the surface for a gloss finish, which will accentuate any underlying faults. Modern paints that promise to do all three in one product are typically pandering to the lazy bawstard market, and are not so successful in arriving at a good finish.
     
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