Print through why and any fix.

Discussion in 'Fiberglass and Composite Boat Building' started by ArAKern, Sep 8, 2018.

  1. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Prior to the pics I would have said what you are seeing is normal for a "roving only" laminate. Roving is about the biggest offender when it comes creating print through, hiding it can be tough even when CSM and other things are used to bury it deep enough to not show.

    But, after looking at the pics I'd say you have something very different going on there, more like an issue with paint and primer products.

    Better pics will help, but this looks like a hands-on cause investigation project.

    Test the hardness of the surface, even just a sharp nail will give you an idea of which layer is deforming.
     
  2. ArAKern
    Joined: Feb 2018
    Posts: 9
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    Location: Southampton UK

    ArAKern Junior Member

    I will test the hardness at the weekend but this is only affecting some sections of 2 panels other 2 other panels are totally understand affected.

    I would assume if it was a painting/paint related issue all panels would have been affected.?
     
  3. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    I would assume if it was a painting/paint related issue all panels would have been affected.?

    I don't think there was any incompatibility between the paint products used.
    I believe you are experiencing crazing.
    Your stated schedule allowed ample time for off gassing of your foundation coats. You didn't mention significant pauses while applying the 2K products. I assume they were applied in quick succession to each other.
    The amount of orange peel in second pic tells me that your painter is heavy handed. It is extremely lickly that minor flaws in the 2K color or early 2K clear coats were sanded. Although dry to the touch, they world not have been fully cured. The scratches allowed solvent from successive coats to be reintroduced in to the uncured core; causing it to swell. It is this uneven swelling that you are calling print through.
    Ondarvr's nail test should reveal failure in the 2K layers. These paints are meant to be applied in quick succession to maximize inter layer bonding; but they must not be distributed between coats. You see the result if they are.
     
  4. ArAKern
    Joined: Feb 2018
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    Location: Southampton UK

    ArAKern Junior Member

    The 2k base coat and clearcoat were shot all in one session as per the datasheet just with the required flash of times. I was in the booth at the time there has been no sanding or flatting back the finish in the photos is straight of the gun. The orange peel section was my first attempt at spray painting I just included the photo because you asked if I was confusing it with print through.
     
  5. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    I don't see any roving pattern in the pics, if it was the actual glass panel the roving would typically show itself.

    Pics are sometimes misleading, but so can explanations when we all aren't using the same terms to describe a defect.
     
  6. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    Assuming it stabilizes, you might fix the warbly areas by blocking and fairing additional clear coats while avoiding any sanding into the glitter. When it's fair, buff to a shine.
     
  7. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    2K clear first time spraying: impressive.

    I can't fathom substrate issues causing your current visual problems.

    How close to ideal were your booth conditions? Temperatures? Humidity? Are the problem spots in areas which had a different environment than the good spots? Greater/lesser ventilation? Sunlight thru window or shady spot?


    Regardless of cause, you have few solution options.

    +live with it as is
    +hope all issues are close enough to surface to be wet sanded and buffed out
    +wholesale sanding and repaint
     

  8. ArAKern
    Joined: Feb 2018
    Posts: 9
    Likes: 0, Points: 1
    Location: Southampton UK

    ArAKern Junior Member

    Just to close out this thread.

    Managed to show it to a master laminator for a very well respected local boat building company and he confirmed it as "Strike through" in his words which I assume is another term for Print through.
    He also got one of their painters to have a look and in his opinion there was nothing wrong with the paint application or hardness etc.

    Also got some feed back from another forum that confirmed it is fairly normal for this to happen when it gets hot did see the panels reach 170 degF when in direct sunlight for a while.

    BlueKanr / SamSam you are totally correct in your solutions (In hind sight just wished I had rolled straight over the gelcoat with a matt colour and been done with it)

    In full disclosure here is what the panels are from (did not want to mislead anyone but forums can be fickle places and I did get the best answers by far from the boatdesign hive mind)
    Bodyworks.jpg https://drive.google.com/file/d/1XwkrnS8vU7Wn1NowZHw4ZezjPffI-y_z/view?usp=sharing

    Many thanks to all
     
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