paints

Discussion in 'Wooden Boat Building and Restoration' started by urisvan, Oct 25, 2014.

  1. urisvan
    Joined: Nov 2005
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    urisvan Senior Member

    i want to paint some parts inside of my boat but i dont know the type of the existing paint. is it ok if i paint with polyurethane paint or do i make a mess if the undercoat is not convenient? As i know, polyurethane can be painted over epoxy or polyurethane primers but what happens if the undercoat is a synthetic or acrylic paint? Is it possible that, the chemical inside polyurethane attacks the undercoat and make a mess?

    And what do you think about acrylic paints? they are cheaper. Do they give good results?

    Regards
    Ulas
     
  2. gonzo
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    gonzo Senior Member

    If it is not compatible, the previous paint will soften and peel off or just get sticky. I have had really good results with acrylic latex paint. The type made for bathrooms is steam and fungus proof.
     
  3. urisvan
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    urisvan Senior Member

    i think undercoat is a stupid synthetic paint. actually i dont want to use any synthetic paint again. it comes out very quickly. and there are many layers, so cleaning all the previous layers is also quite difficult and it will make a lot of dust, maybe it can be a project when i am in shipyard again but now i am sailing and i dont want that mess.

    is acrylic or polyurethane paint compatible with synthetic paint? or what do you suggest?

    best regards
    Ulas
     
  4. messabout
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    messabout Senior Member

    A good primer of water based acrylic type, followed by a water based acrylic house paint is practical, reasonably priced, durable, and easy to apply. It is unlikely that it would attack the undercoat. If you want a glossy finish then this is not the solution, but it is available in semi-gloss finish.

    Primers in the US have brand names like Kilz. It apparently sticks to almost any clean surface. I have had very good results with the primer/acrylic finish coat applications on numerous boats. The only admonition is that that kind of paint needs a seasoning interval of time of ten days or more before serious exposure to water.
     
  5. gonzo
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    gonzo Senior Member

    There is a water based graffiti covering primer that sticks to almost anything.
     
  6. PAR
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    PAR Yacht Designer/Builder

    Scrub the area of old paint with denatured alcohol and on a rag. If you get some color on the cloth, it's an acrylic, if not it's an alkyd or polyurethane.

    I'm not sure what you mean with "synthetic" paint is, but there's really only three basic paint type, acrylic (water base) alkyd (oil base) and polyurethane (modified oil based).

    Considering your location, you very probably have an alkyd paint, possibly (likely) with lead in it.
     
  7. urisvan
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    urisvan Senior Member

    thank you very much for your answers.

    messabout, actually i will use it inside the boat so semigloss or even no gloss is better for me. and it will not meet with water so acrylic seems likeva good solution as i understand. is it easy to clean?

    PAR, i really dont know much about paints but i have a stupid paint that unfortunately used it for the toerails. you use "synthetic thinner" to make it thinner. that is why i used this term "synthetic paint". it is very bad paint. it comes out very easily if something scrubs on it. what is that actually?

    Regards
    Ulas
     
  8. urisvan
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    urisvan Senior Member

    there are paints which use cellulose thinner for make them thinner. which kind of paints they are? some car paints are like that. i used some of them some time ago and they were good as i remember. So for me paints are two types: ones use synthetic thinner and ones use cellulosic thinners.
     
  9. PAR
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    PAR Yacht Designer/Builder

    Cellulose thinner known as laquer thinners in some countries, and typically contains methyl isobutyl keytone. This is an old chemical concoction and was used with enamels, before less "hot" solvents where developed. In most western countries, they haven't used this stuff in decades. The paint is still an alkyd and reacts the same way. It's not very hard which is why it rubs off easily, tends to yellow and crack in time too, so you'd be best advised to remove what you have, so the next coating has a good base to attach to.
     
  10. urisvan
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    urisvan Senior Member

    thank you very much PAR,

    Are acrylic paints better than alkyd paints? i think both of them are soft. acrylics are water soluble, alkyd are using some other solvents?

    messabout says that (as i understood) , acrylic is better and can be even used in topsides. doesn't come of easily when you rub it for example. is it right?

    i think for outdoor use on my toerail it is better to remove my existing paint, and use epoxy and polyurethane over it. i guess it will be a good solution. what do you think?

    for indoor use, i will take out the loose paint and make a good sanding and use some acrylic paint over it. i will not use alkyd. does it sound correct? or alkyd is better?

    sorry for many questions, i would like to understand the story.

    Regards
    Ulas
     
  11. gonzo
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    gonzo Senior Member

    Do you mean acrylic latex (water solvent) or acrylic enamel (hydrocarbon solvent with a hardener)?
     
  12. urisvan
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    urisvan Senior Member

    another thing to learn.
    the water soluble sounds very weak?
     
  13. gonzo
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    gonzo Senior Member

    Not at all. They will last decades in an interior application. For exterior, like in a house, they need repainting every 4-8 years depending on the climate.
     
  14. urisvan
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    urisvan Senior Member

    so perfect,
    water soluble acrylic paint looks like a perfect solution for me. i guess they have less odor after you paint. Though i read that it can take a month untill it completely cures. does it smell meanwhile? i dont want smell during the Atlantic passage!

    and i guess i can paint it over most of the substrates. isnt it?

    i also dont want gloss look interior.

    And is it easy to clean with water, detergant and sponge?

    again many questions, sorry, life is so difficult, one need to be also a chemical engineer if he is sailing.

    Regards
    Ulas
     

  15. gonzo
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    gonzo Senior Member

    Acrylic latex paints dry in a few hours.
     
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