Black painted fibreglass?

Discussion in 'Fiberglass and Composite Boat Building' started by JordieS, Nov 10, 2011.

  1. JordieS
    Joined: Apr 2011
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    JordieS Junior Member

    Hi everyone,

    I wasn't exactly sure where to put this but I have heard that if you have a fibreglass boat/vehicle and paint it black, when left in the sun it could cause the bodywork to heat up so much that it deforms/melts.

    Has anyone painted a fibreglass boat black? I've seen boats with black sides but never seen any with a black deck.

    Apart from being hot to touch, if a boats deck was black would it cause deforming, melting?

    It is probably a stupid question but I just want to know

    Thanks
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Melt, definitely not. Deform, unlikely. But probably not practical in warmer climes.
     
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  3. michael pierzga
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    michael pierzga Senior Member

    Dont paint it black.
     
  4. Jeremy Harris
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    Jeremy Harris Senior Member

    It's potentially a big problem, painting GRP black, or even a dark colour, depending very much on the resin used and the cure schedule.

    Most resins start to soften at fairly low temperatures, less than 100 deg C. A black painted, reasonably well insulated (underneath) surface can easily reach this temperature, maybe a lot higher in really bright sunshine with little breeze.

    The result is that the composite softens and loses significant amounts of stiffness and strength when it's hot. The main problem for a boat is likely to be "structural relaxation", where a composite component that is under stress may deform when heated and then remain deformed when it cools and re-hardens.

    It's a big issue with composite aircraft, where they both ensure the skin is a light colour and use resins with a high transition temperature to get around the problem. Unfortunately, to get a high transition temperature usually means curing the resin at high temperature. Even then, getting a transition temperature much higher than 120 deg C is challenging without using special resins (usually epoxies, rather than polyester or polyvinylester).
     
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  5. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    ...yes, painting a boat black will certainly cause problems in the hot areas especially, beside not being able to walk on the deck......
     
  6. tunnels

    tunnels Previous Member

    Last black boat i painted was for a french man . Stood out on the water but yes it got really hot up round the islands and that was just because the hull that was black ,never heard from him again after he set sail for home !
    You would have to be AUSTRALIAN to think of painting a deck black !! If you have friends and kids they will never love you again !!
    Go paint two big panels ,one black and the other white and put them in the sun for a hour or so !, Then drop your pants and your undies and sit on the black one first !! After you climb out of the neighbours tree and hobble back then do the same on the white panel if you dare !! you can decide why you should never paint a deck black or any dark colour , blue ,green , red or black while yourwife is peeling the burnt skin of your back side !! :(.
    I am being kind and not calling you a idiot :D
     
  7. Poida
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    Poida Senior Member

    Hi Tunnels

    When I was in the paint industry, I thought it would be a good idea to manufacture a light coloured roof paint, even a white one.

    We use to do coatings for a roof tile manufacturer who basically only produced dark colours. I asked one of their marketing people why they didn't sell white tiles to reflect the Sun's heat.

    He told me that they made some light coloured tiles as a market research when people chose what coloured tiles they wanted for their house. Noone wanted them, they all chose dark colours. In our heat.

    Tunnels, Australians are not mad, we're F^#*ING stupid.
     
  8. michael pierzga
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    michael pierzga Senior Member

  9. JordieS
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    JordieS Junior Member

    The heat wouldn't be a worry as if I do it I would install Tek-Dek decking in the areas you would walk (mainly up the bow for dropping anchors, tying up bollards etc). Also the boat is only 20ft long so touching isn't really an issue, only not melting/warping is an issue.

    Thanks
     
  10. JRD
    Joined: May 2010
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    JRD Senior Member

    Some of West Systems light weight fillerers are recommended not to be used under black paint due to their intollerance to heat.
     
  11. sean-nós
    Joined: May 2010
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    sean-nós Senior Member

    There are only two colors to paint a boat, black or white, and only a fool would paint a boat black.
    -Nathanael G. Herreshoff :D

    I'm in Ireland so no worries about the heat :D
    [​IMG]

    [​IMG]
     
  12. JordieS
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    JordieS Junior Member

    Is that gelcoat? And did you spray it on or brush it on? Because it looks quite smooth.
     
  13. sean-nós
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    sean-nós Senior Member

    It's just paint over fiberglass and was put on with a roller and sanded between each coat then sanded with 600- 800-1000-1500-2000 wet and dry and then buffed to give a piano black finish.
    I hate sanding :D
     
  14. JordieS
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    JordieS Junior Member

    What did you use to sand it?
     

  15. JordieS
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    JordieS Junior Member

    Is it Gelcoat or just normal paint? Did you have to clearcoat it?
     
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