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Thread: Bottom paint adhesion to 5200

  1. #1
    Join Date
    Sep 2000
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    Chemist or anyone,

    I have an area on my boats bottom which for complex reasons (swelling of different adjacent surfaces and unusual shape) I am not sure how to seal. A maybe crazy thought which came to mind is to cover the area with 5200 and paint. So the question is how well will bottom paint adhere to a larger area of 5200? The area is 2 to 3in X several feet long. I know there are more traditional approaches but the situation is more complicated than it sounds.

    Thanks in advance,
    Dave

  2. #2
    Join Date
    Feb 2002
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    Duncan, Vancouver Island
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    Originally posted by Dave Williams:
    Chemist or anyone,

    I have an area on my boats bottom which for complex reasons (swelling of different adjacent surfaces and unusual shape) I am not sure how to seal. A maybe crazy thought which came to mind is to cover the area with 5200 and paint. So the question is how well will bottom paint adhere to a larger area of 5200? The area is 2 to 3in X several feet long. I know there are more traditional approaches but the situation is more complicated than it sounds.

    Thanks in advance,
    Dave
    Hi Dave. I haven't the foggiest answer to your question but why not humour us? How complicated is it? Also, there are several anti-pychotic medications on the market that might be more effective than 5200. (joking [img]smile.gif[/img] ).

  3. #3
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    Sep 2000
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    JimD,

    Thanks for your interest. Not sure I can describe the problem on the computer. A combination of previous owners (some very knowledgable) giving it their best shot and my own lack of knowledge. People much more talented then myself have given it some thought.

    Anyway it was just a thought.

    Plus since I started this rebuild I have tried all the anti-psychotic medications and nothing has worked. (Joking also )

    Here's to kindness,
    Dave

  4. #4

    Post

    4200 is a low-modulus version of 5200. 4200 is softer and stretches more easily thus for a given amount of movement has much less tendency to tear off the surface.

    If you paint the antifouling paint on before the 4200 or 5200 has really cured, which-is-to-say-slightly tacky, the isocyanates in the elastomer should bond to whatever in the antifouling paint, and a couple days later the result should be that the bottom paint would be glued down by the sealant. If you wait until the 4200/5200 is fully cured you will get not-as-good adhesion of the paint to the [cured] sealant.

  5. #5
    Join Date
    Feb 2002
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    Originally posted by Dave Williams:
    JimD,

    Thanks for your interest. Not sure I can describe the problem on the computer. A combination of previous owners (some very knowledgable) giving it their best shot and my own lack of knowledge. People much more talented then myself have given it some thought.

    Anyway it was just a thought.

    Plus since I started this rebuild I have tried all the anti-psychotic medications and nothing has worked. (Joking also )

    Here's to kindness,
    Dave
    Aw, what the heck does Chemist know about antipsycotics

  6. #6
    Join Date
    Sep 2000
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    Bump again. I'm trying to keep these 5200 4200 threads together. What is the difference chemically between the two. My test with 5200 and bottom paint was very satisfactory. Is oil based enamel over 5200 a different animal.

    Sure would like to know since tomorrow I'd like to do it!

  7. #7
    Join Date
    Sep 2001
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    USA
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    I and a lot of others in the same marina used 3M 5200 and painted with soft bottom paint and never had a problem. Sometime the paint was applied within minuits of applying the 5200 other times it was days or even weeks after. Never a problem.

    But as they say, "Your milage may differ"

    G

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