Removing Gelcoat

Discussion in 'Fiberglass and Composite Boat Building' started by wesley Sherman, Aug 19, 2020.

  1. wesley Sherman
    Joined: Jan 2020
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    Location: New York

    wesley Sherman Junior Member

    I have an Alberg 30 I am restoring.. Winters I am inside and summer working the outer hull.
    This boat had extensive crazing. The surveyor look at the area I sanded down to gel coat and we both came to the belief its dry. Gelcoat So in an effort to stop the cracks from coming through the new paint. I have mostly removed the Gelcoat in some areas pretty much to fiber in most areas now its is just so thin a Gelcoat that you can see the grey of the fiberglass behind. 80 percent of the crazing cracks are pretty much gone. there are however some very light cracks that can be seen. when looking close.

    Any thoughts and ideas should I continue and remove most or all... of the Gelcoat. Speaking with Interlux a few times. I get varying thoughts. No one there at inter lux I've spoken to don't know if this thin of Gelcoat crack would print through 5 coats of 2000e. then the topcoat. No one won't say it will no one will say it won't.

    Wondering if anyone has any practical experience or thoughts in this regard. I am not replacing the Gelcoat. Above the waterline at all. The Gelcoat below the water line underneath about 6 coat of barrier that I can count from alternating colors and crazy thick ablative paint is fine. So boot stripe and above it is now history. Comments are appreciated if anything other than re Gelcoat it, as that is not happening. one last note.. the areas with the worst crazy was in areas that turned out to be so bloody thick Gelcoat.

    Interlux guys all pretty much said to use this process. Any impact crazing clear to fiberglass assess and if fiberglass structure and not severely damage lay a 6oz fiberglass over the area and use West 105 resin on it sand fair.

    Then a slightly thinned coat of 2000e Then about 5 coats of Barrier regular. Then topcoat of choice.
    I spent a lot of time and cussing but the current condition of the hull is very smooth and even. Almost feels as if the Gelcoat is on it other than the areas were I have to fix some slight impact areas. in the undamaged areas, I have faired any low areas and longboarded above the waterline. Just explaining exactly where I am at.

    Sorry for the long-winded post.. but thank you for your ideas and comments
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    You could try a test of the intended system on an area that is least conspicuous, but representative of the rest of the boat. Then decide.
     
  3. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    I'm glad you stopped talking to the Interlux sales team.

    2000E would eventually get the job done, but not affordably or efficiently.

    To give focused advice for you on your Alberg we need some more information, and lots of pictures.

    What is your intended level if finish. 0-10 start point to perfection
    What is your experience with paint application?
    What application technology do you intend to use?
    What types of sanders/grits have you been using?
     
  4. ondarvr
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    Location: Monroe WA

    ondarvr Senior Member

    The typical reason for crazing is an incorrect catalyst ratio, being thick compounds the problem.

    The physical properties of the gel coat are severely compromised due to this, and after several years the crazing begins.

    Any gel coat left on the surface has the potential to fail, so applying a coating over it has some risk.

    Nobody can give a true answer because there's no way to know just how the leftover gel coat on the surface will continue to age.

    It could survive fine for the next 50 years, or fail next week, both outcomes happen.

    Fortunately it's mostly a cosmetic problem, so do whatever let's you sleep well at night.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Interesting, ondarvr, when you say incorrect catalyst, do you mean too much catalyst ?
     
  6. wesley Sherman
    Joined: Jan 2020
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    Location: New York

    wesley Sherman Junior Member

    Crazing was in my opinion and many others that have looked at it due to sitting so long in the Sun.. the previous owner died and I found it by accident. I actually found a few pictures of it from the marina that had it and had photographed it to try and sell it long back.. There is a short history of the boat with some damage that had been repaired and I uncovered it and it was well repaired.
    Anyway, I digress. My intention is to cover it in 2000e and then to top coat. I don't want a glossy showroom finish.. just properly sealed and smooth matte is what I intend. I want a nice smooth hull. I will be sailing for months and months when I am done, and I don't want it hard to do repairs and nonsense when in other countries. So no fancy Gelcoat is desired.
    I have done a bit of painting on other sailboats over the years. My father was a custom boatbuilder back in the 50s. I did learn a lot from him. My paps and I sailed when I was a youth all over the pacific in a 43' wood ketch during the summers and once for near a year when I was home studied aboard. But that was many years ago and I was a youth. I know some and search for the answers I don't know.

    I will get some pictures of the hull when I am back home again. I am starting to believe that I best just remove all to bare glass. Right now the Gelcoat is so thin you can see fiberglass under it, how thin it is on most places that it not already bare.
    Its been a lot of work, sanding Gelcoat is not about joy. I guess part of me was wanting to stop the sanding at this point due to the time involved and the extreme boredom. So basically was looking for hope that I could sand out most all gelc cracks and the others being so fine that the crack might not affect the 2000e and show through. I have to say the gelcoat is not weak in any means or deteriorated much. The several hundred sanding discs will attest to. LOL

    I used 40 grit inline sander with a flexible sanding head that conforms to the shape of the boat to grind through most the Gelcoat. Then I went to work with an Air Sander 6" with soft backing with 80 grit. After that, I've finished it off to where I am now with 60 to slow the removal. I've also long boarded the above the waterline ( a bit too early if I need to remove all the gel)

    My intention is to apply all the barrier coat epoxy in one long shot.. I have my RV and do it all in one very long shot. I will or thought I should apply and extra 1-2 coats because I will sand out any eggshell for the most part so that when I spray the top coats it will be smooth. I am using or was going to use west system epoxy filler or watertight interlux for any fairing before the painting.

    To answer the question that blue made about inter lux and affordability and efficiently. Could you expound on that information? I use interlux I suppose because I know it well and feel comfortable with it. Not saying I am an expert at all, I am not. But I've been comfortable with it due to many uses. And never had anything I used it for fail or not turn out well. But that being said I am not close-minded to options and new information.

    Last but not least, I don't think I know anything, I learn by trial and error and realize there must be better ways or new ways.
     
    Last edited: Aug 20, 2020
  7. ondarvr
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    ondarvr Senior Member

    It can be either under or over catalyzed, both situations lead an undercured condition. Rarely does gel coat craze from age or sun, although extremely thick gel coat can.

    Normally its a combination of catalyst and thickness.
     
  8. ondarvr
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    ondarvr Senior Member

    What grit are you sanding with, and what type of sander?
     
  9. wesley Sherman
    Joined: Jan 2020
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    wesley Sherman Junior Member

    Ondarvr all that info is in my last post.

    Ive sanded Gelcoat in the past on other boats but this boat was crazy thick on the fatest areas of the boat... the prow and aft were relatively unaffected by the crazing. These areas the gelcoat took half the time to sand. And to mention again the crazing wasn't from any impacts. There is an obvious difference. Thank you
     
  10. ondarvr
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    ondarvr Senior Member

    sorry, I didn't go back and check.

    I normally test a couple of different grits to see which sands quicker, not every gel coat will sand the same.

    24 grit typically wears out too quickly, so 36 tends work better, but the type and quality of the grit plays a huge part. 80 is the finest grit I used, and that's only when I didn't need to remove the gel coat.

    Start with whatever removes it the quickest, when you get close to having all the gel coat removed, then pick a method and tool that preserves the surface profile.

    But don't necessarily go with a finer grit, you don't care about the scratch size or depth, just ease and speed of removal.

    I had my own business that did this type of work, we would grind for days on end before refinishing whatever it was we were working on.
     
  11. wesley Sherman
    Joined: Jan 2020
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    Location: New York

    wesley Sherman Junior Member

    Thank you ondarvr...
    I could have used 40 all the way to the place I am it doesn't remove fast at all, it good paper doesn't foul out very fast. I had figured 40 grit would eat it up but that wasn't the case. Ill probably use the inline air sander with the flexible head that forms to the boat hull to remove the last bit. As I have decided I have come this far, might as well put in the few more hours per side.

    Blue said before "2000E would eventually get the job done, but not affordably or efficiently." is there a better system to seal the boat that I had intended? 2000e and a matte topcoat. I should say I am only talking about the above the waterline boot strip up.
    One question I do have is maybe it's my imagination it seems when most the tan Gelcoat is removed there appears to be a another white layer of something is this some sort of Gelcoat seal when they molded the boat

    I really appreciate everyone's time and input.
     
  12. ondarvr
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    ondarvr Senior Member

    Whatever color is sprayed first has over spray behind it from the other colors after it.
     
  13. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    Westley
    Your experience with Interlux is precious. Well worth the slight increase of cost. I shan't try to diswade your use of their products.

    I was coming from the perspective that most of the boats that I have seen where the gelcoat was removed would require closer to 50 coats of paint. Your description of your process leads me to believe that you won't need quite that many.

    As Ondrvr said, the remaining gelcoat will fall off of the hull eventually.

    You keep saying "smooth". Are you looking for simply smooth?Or smooth and fair?

    My approach:
    Remove remaining gelcoat with 60 grit.
    1/8 - 3/16 inch thick coat of epoxy fairing compound.
    Fair with 60 then 80 grit on a longboard.
    Three coats of 2000E
    Smooth with 300 grit.
    Interlux top coat of your choice
     
  14. wesley Sherman
    Joined: Jan 2020
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    wesley Sherman Junior Member

    Thank you Blueknarr

    I am not looking for a 10 finish at final what i want is a hull that doesn't show up waves or undulation just not shining. It's a boat that will serve me not show off to anyone, kinda a nice workboat? But looks like it was done with pride make any sense.

    I have to ask about the 1/8 fairing you suggested. I asked this to Interlux and they said no need for this... not that they know everything that is why i am seeking practical knowledge, not office technical stuff.

    The last guy i spoke to said this.. fix any cracks that need to be fixed with west 105 and 6 oz cloth.. sand and fair... then when ready to coat, thin with interlux thinner 10% and roll on. Then sand lightly and recoat with the same formula within 4-6 hours.
    sand lightly and wash then let dry and then wash with a wipedown can't remember the name right now. Then do 5-6 coats of 2000e. He did say if I plan on smoothing it you smooth to remove the eggshell then I might want to do another coat then sand.
    He suggested we do this all in a close time frame not the max time between coats.

    Another tech said the same thing but added in to paint the first two coats with high build primer the interlux hs then the 5 coats of barrier coat, then topcoat. We won't even say what the first guy said.. cause the other two said they were going to speak to this person for his advice.
    I also spoke to the son of a well-known boat builder a year or so ago, said pretty much the same thing. This advice came because of what he asked me i wanted to do with my boat and what I expected from my boat.


    And it is this. I am 54 I when I finish will be traveling a lot offshore for months at a time. I want a boat that is durable, easy to repair paint. Want solid boat that will serve me well but not have to do Gelcoat repairs etc or extensive cosmetic work to make it look like a boat that sits in a marina. I don't mind some imperfections, they don't bother my ego. Don't want it to look like a mobile home in a park of alcoholics either lol

    Why I am seeking advise from the practical use community for things and knowledge they gained from use not just tech stuff.
     

  15. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    The Ilux guys get paid to sell Ilux. They don't get paid to sell fairing compound. Ten coats of 2000e will be about the same thickness as one coat of fairing. But cost about five times as much and take five times as long to apply.
    10% is a lot of thinner. Why thin when the goal is to add thickness? More commission for Ilux sales team

    Don't get me wrong. I have used Ilux. It is good stuff. Ilux makes it easy to achieve great results.

    Paraphrasing Ondrvr
    -Remove dead gelcoat with as coarse of grit and an agressive sander but be careful to not lose the surface profile. ( I mentioned 60 because I thought it was what you used before)
    -Restore surface profile with fairing compound (not primer)
    -Prime and paint.

    I believe that you are using greater care than most. Your goal could be reached with less (1/16" of fairing compound)

    Edit
    Checked the specs for the film thickness of the 200E. Interlux recommends 2.5-5.4 mils dry film thickness. At 3 mils it takes 20 coats to achieve 1/16 inch thickness.

    Why are they recumending their most expensive anti-osmotic blister preventing primer for above the water line use?
     
    Last edited: Aug 21, 2020
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