Sanding out weave of fiberglass

Discussion in 'Materials' started by John Anthony Noble, Mar 2, 2019.

  1. John Anthony Noble
    Joined: Mar 2019
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    John Anthony Noble New Member

    I have recently purchased an ip24 boat and it needs a total repaint the problem is the whole outside of the hull has no gel coat and is rough weave fiberglass I obviously want a good smooth finish to enable a good looking paint job but I have no experience working with fiberglass so looking for tips please.

    Should I sand out the weave then reduce the grit size until smooth and apply coats of resin to the hull or are there other options ?

    I have attached a few photos below.

    Regards

    John. IMG_5988.jpg IMG_5989.jpg Screen Shot 2019-03-03 at 02.35.06.png IMG_5989.jpg IMG_5989.jpg Screen Shot 2019-03-03 at 02.35.06.png
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Don't sand it, at least initially, you should fill it, probably epoxy based filler that will sand easily, and sticks to just about anything, without dissolving the paint, or depending how rough it is , a high-build epoxy primer (paint) might be enough. Then you can sand with long-boards, and eventually get a surface good enough to paint over. What you paint with, might depend on what that blue stuff is, a two-part Polyurethane might attack it, but ordinary boat paint probably good enough, and will cover what you have, in all probability.
     
  3. JamesG123
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    JamesG123 Senior Member

    You can't "sand out" when you are already down to the glass. All you will do is keep going into it and strands will keep popping out. That boat was either a failed gel coat that someone decided to finish anyway, or someone tried to strip the paint off with chemicals and managed to remove the gelcoat too.

    Your only real option is to sand off that blue paint and then spray and sand a bunch of layers of epoxy to get it fair again. A ton of time and expense. Or just leave it ugly as sin as it is. I guess its PO decided on the later. Now its your problem.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    It just looks like a home job of glassing, never been a gel coat, the blue is paint, to my eye, I would experiment with a small area to see if epoxy filler sticks to it without misadventure. If it does, that is the way to go.
     
  5. JamesG123
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    JamesG123 Senior Member

    But if it is an actual Island Plastics 24, its hard to believe that they would have let that bad of a finish leave the workshop.
    I once tried to be lazy and remove a bad, thick, heavy, automotive metal flake paint job off a piece of chopped mat FG with some of that gel paint stripper. It produced a scar tissue surface very similar to the OP's pics.
     
  6. fallguy
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    fallguy Senior Member

    Very quickly; you do not want to sand this too far down.

    For a moment, if the boat had not been painted, you would add a fairing mix of some sort and fair the hull until a perfect smoothness and then paint or gelcoat.

    Unfortunately, the paint creates a less than ideal surface for bonding.

    And the exposure of the surface to the elements would give me pause on gelcoating.

    I would probably try sand just a bit with a random orbital sander and 40 grit...or sandblast with a media that removes paint without removing lotsa glass. Although visions of embedded sand also are not ideal.

    Then use thickened epoxy. Thicken with cabosil and balloons to fill it all. Something on the order of 1:1:2 ...epoxy,cabosil, balloons. A little bit wet and even use peelply to help with adhesion while avoiding runs.

    It will take a lot of work and quite a bit of filler.

    Limit epoxy batches to about 12 ounces of epoxy and use a hawk or board to keep the mix flat to avoid it kicking.

    After the initial fill; you would be able to mix subsequent batches a little less epoxy and skip using peelply, just sand in between.
     
  7. fallguy
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    fallguy Senior Member

    Mr E is correct. The adhesion might fail, so try a few areas first and try to remove them with a metal knife.

    Looks like someone stripped gelcoat to me and then just painted.
     
  8. Blueknarr
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    Blueknarr Senior Member

    John,

    Welcome to the forum.

    As you can tell from all the previous replies, you purchased a bit of a problem.

    The Blue paint poses several issues
    • It will be a weak link to any future coatings
    • It will be very difficult to nie impossible to remove
    Every method of paint removal (grinding, media blasting, heat and chemical strippers) posses dangers to the underlying fiberglass. Its a matter of picking your poison. Try the options in small tests to see which is most efficient with minimal collateral damage. Don't be surprised if one technique is best in certain areas while another in other zones.

    Fairing directly over the blue may work. Or might not. My worst fear is that the blue will gradually fail. Requiring frequent touchups.

    Hope you didn't spend a small fortune.

    Good luck
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    There's no sign of the paint losing adhesion. There might be an epoxy primer under the blue ( some kind of light coloured coat there). You could check the adhesion of the blue, by making an "X" with a razor blade, pressing on some cellotape, and peeling it off. If the blue does not lift with it, all should be well.
     
  10. Sparky568
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    Sparky568 Junior Member

    I agree with Blueknarr. Some testing will be required. Opinions are one thing results are real. As far as a filler goes I would use epoxy or at a minimum VE below the waterline with any of the fillers listed above. Above the waterline you can save some money by using a poly based fairing putty then spray or roll gelcoat. Either way you've got quite the project ahead of you. Best of luck and for the benefit of others post your resolution.
     
  11. JamesG123
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    JamesG123 Senior Member

    Look again. Most of the pics have places where the blue has been scraped off without much apparent effort (no sanding/scouring etc.). And it doesn't even look like a very good coverage either.
     
  12. BlueBell
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    BlueBell Ahhhhh...

    Is it sound?
    Was it layed up correctly?
    Very possibly not or it wouldn't look like this.
    That doesn't mean it's not sound, but the odds are against you.
    If you don't know it's history, you're going to have to do some testing.
    If it proves to be sound then either leave it as is, or soda blast the blue off,
    fill with thickened epoxy, fair (sand) and paint.
    As usual, the less work, the better.
    Good luck.
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    It looks like scrapes on the high points have scuffed the paint, which is not surprising, because it is concentrated contact on a raised point, not a flat area. And those raised points will have minimal paint. I doubt they even bothered to sand the "nib" before painting.
     
  14. Yellowjacket
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    Yellowjacket Senior Member

    Putting epoxy on top of paint like that is just compounding the problem. The epoxy will stick to the paint and the paint will peel off of the glass and it'll come off in chunks. Given that it was never faired properly you're going to have to use something like media blasting to get it off. The good news is that after you do that and clean it with a solvent the epoxy filler will stick like crazy.
     

  15. JamesG123
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    JamesG123 Senior Member

    More like a stucco job than fairing. lol.
     
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