Repairing Crazed Gel-coat

Discussion in 'Fiberglass and Composite Boat Building' started by LMB, Nov 3, 2008.

  1. LMB
    Joined: Nov 2008
    Posts: 52
    Likes: 2, Points: 0, Legacy Rep: 37
    Location: North Carolina

    LMB Junior Member

    I find myself routinely researching materials and methods to ensure that we are delivering the best in terms of workmanship and efficiency. A nagging concern for me is a method to repair crazing in aged gel-coat surfaces. This problem is sometimes severe, as we have seen with a number of old Boston Whalers. The owners don't want to junk these boats, in fact they are very interested in making them new. I don't think it's practical to completely strip the gel-coat and lay new glass. The alternative would be to resurface the boat with resin based fairing materials that would hopefully fill,seal and bond the old cracking gel-coat and effectively resurface the boat. This has been our approach in the past and I have advised my customers on no long term guarantees. One of the worst cases we have repaired, is holding up well after 3 years, but it has only been used 6 to 8 times. I run an honest business and want to offer customers solutions and practical advise ( although restoring an old boat really isn't practical). Do you have any opinions on repairing this type of problem?

    We have used Duratec's vinyleseter primer, and I'm looking at epoxy products as an alternative. Marine Tex's Gluvit is marketed for exactly this purpose, but there is no technical data and few professionals seem to use it. Adtech makes an epoxy high build primer, but I'm not so impressed with there technical data. Is it all in vain? P.S. - look for my other post concerning technical data.
     
  2. ondarvr
    Joined: Dec 2005
    Posts: 2,093
    Likes: 186, Points: 63, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    There's no good and easy way to fix crazing and it can have several causes, each cause pretty much requires the gel coat in the crazed areas to be removed for it to be succesful
    Crazing can be from poor cure, gel coat being too thick, or too much flex in the laminate. The problem is if the cracks aren't removed there's a very good chance they'll be back soon. Epoxies can be used to cover the cracks, but you're relying on the epoxy to be strong enough to bridge over the cracks and not fail, but as soon as it gets stressed enough it will crack again.

    I hate repairing large areas of crazed or cracked gel coat, its a great deal of work and if the cause of the crazing or cracking isn't taken care of then its sure to return.
     
  3. bntii
    Joined: Jun 2006
    Posts: 731
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    Location: MD

    bntii Senior Member

    I have seen no sure method outside of grinding to base and fairing/painting.

    Cracks started by laminates 'hinging' about corners need the laminate reinforced.
     

  4. Deeman
    Joined: Jul 2006
    Posts: 50
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Enon, Ohio

    Deeman Junior Member

    bntii has got it right. Flexing of the glass causes the crazing. In my hot rod days I had a till front end/hood assy. It would always craze the paint and or crack. The only way we solved it was to put re-enforcement pieces in underneath those areas. That car is still around the show circuit here, same paint, and no more crazing issues.
     
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