Tips on applying (by brush) & sanding gelcoat

Discussion in 'Materials' started by mrdebian, Oct 12, 2021.

  1. mrdebian
    Joined: Apr 2021
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    Location: Greece

    mrdebian Junior Member

    Hi all,

    Is it possible from your experience to sand the gelcoat as seen in the picture (it is quiet thick) in order to get a smoother appearance and ger rid most of the brush lines?

    Am I right if I sanded with 100 grid and then polish it or there is a better procedure?

    Any help is very much appreciated.
     

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  2. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    There are ways to finish gelcoat. I am not the expert.

    I would say you need to share more about what we are looking at..did you gc over a seam?

    100 grit will be dreadfully slow if you are very high above the desired; maybe start with 60 until you get closer or wait for some gc guys to advise

    @ondarvr is really wise on gc
     
  3. mrdebian
    Joined: Apr 2021
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    Location: Greece

    mrdebian Junior Member

    The picture shows the bow of a kayak; the small red part is the deck and the white the hull. The join made with one aramid tape inside and one glass outside. Above the outside tape (after sanding) is been applied the gelcoat but is very ugly as I don't have experience with it and trying my best....

    Thanks
     
  4. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    I would put some masking tape down on the original side; maybe two layers before you sand so you know if you are hitting the old. You don't want a low grit against the old stuff or it'll scratch.

    But wait for some better advice.

    I would use a sanding block and keep working it with 60 grit until it is even with two layers of masking; then raise the grits, but I have very little gc experience; so wait for others.

    Is the tape proud of the other gelcoat? If so, it can never be fair.
     
  5. mrdebian
    Joined: Apr 2021
    Posts: 21
    Likes: 4, Points: 3
    Location: Greece

    mrdebian Junior Member

    @fallguy I'm not following you about the "proud of the other gelcoat". What do you mean?
    The first layer sprayed but the result wasn't good (very thin and many small holes maybe from air pressure or gun settings) and the 2nd layer applied by brush with a lot of gelcoat in order to sand it afterwards.
     
  6. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    Protect the original finish after with duct tape over blue masking tape. To prevent sanding thru original gelcoat.

    Start sanding with 100 grit on a stiff block.
    Work to finer grits.
    Remove protective tape at 240 grit.
    Wet sand with a flexible board from 400 to 1000 grits.
    Polish
     
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  7. mrdebian
    Joined: Apr 2021
    Posts: 21
    Likes: 4, Points: 3
    Location: Greece

    mrdebian Junior Member

    @Blueknarr can I use a sander tool or it needs to be with hand? At least the first 100 grid to save some time.
     
  8. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    I would not bother with power tools for a repair of a only a few inches by a foot or so.

    You will be surprised by how fast 100 grit will cut down those brush tracks.
     
  9. mrdebian
    Joined: Apr 2021
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    Location: Greece

    mrdebian Junior Member

  10. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    I didn't realize that the repair extended beyond the photo.

    The use of power tools for fairing comes up often. Power tools can be used--but they usually do more harm than good.
     

  11. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Run the power until you hit the tapes then switch to hand tools.
     
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