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Thread: Resealing Lexan glass in a hatch I made

  1. #1
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    Default Resealing Lexan glass in a hatch I made

    Was having trouble keeping the glass sealed, maybe cause it's Lexan. Plastic is 1/2 inch thick, one side is UV coated.

    So decided to try another way. I used sikaflex flowable concrete sealer, and 1/4 inch polyethylene backer rod on a roll from Amazon as a springy gasket seal.
    So far it has held for 3 months without coming loose. I figure the Lexan moves more than the wood hatch stressing the sealer, which did not want to adhere so the springy backer rod should move too and keep it watertight.

    I also painted with spray paint primer, and Minwax polyurethane gloss under he gray to help seal the hatch


    Lexan laid in hatch with sealer


    Here I am forcing the backer rod into the space. One continuous piece all the way round. Slipped in easily.


    Weighted down to let it set a little.



    Sikaflex from H Depot wa $8


    Scrubbed, wet Sanded and cleaned up excess. I probably should have used painters tape, but this Sikaflex cleans up next day with a scrunge and soap on the gray, carefully cleaned the Lexan, I may have used a solvent like 90% alcohol. Sikaflex takes a few days to fully cure.
    I then painted it with Rustoleum gloss topside white. If I did again, would have used a white primer, takes too many coats of white to cover gray. but it was heavily thinned paint.


    https://photos.google.com/share/AF1Q...U4M0sxS1JVNUpB
    Last edited by sdowney717; 07-10-2017 at 05:40 AM.

  2. #2
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    Default Re: Resealing Lexan glass in a hatch I made

    Hope it holds well for you. I tried 5200 to seal my lexan windshield after scuffing lexan edges to give it something to grip to. Came loose while trailering down the interstate, duct tape to the rescue.

    https://www.flickr.com/photos/134722...posted-public/

  3. #3
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    Default Re: Resealing Lexan glass in a hatch I made

    I did sand the edges. but Lexan seems to be slippery stuff. The springy backer rod will save the day here, I think.
    And the concrete seal is soft and very stretchy.
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    Could you see the pictures inline?
    I can see them in Chrome, but not in Firefox.

  4. #4
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    Default Re: Resealing Lexan glass in a hatch I made

    First picture, yes others no.

  5. #5
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    Default Re: Resealing Lexan glass in a hatch I made

    Ok, doing test to see if I can see it in firefox.
    I see it in Chrome, will edit to say about Firefox.

    Got a shared picture link from google photos, then add ?.jpg and posted it here.

    Yes, that works, add ?.jpg to all picture links from google photos, I see it in firefox now.

  6. #6
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    Default Re: Resealing Lexan glass in a hatch I made

    Post 5 is visible on Chrome, no others.
    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

  7. #7
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    Default Re: Resealing Lexan glass in a hatch I made

    Quote Originally Posted by PeterSibley View Post
    Post 5 is visible on Chrome, no others.
    I see it in Firefox, but I also did log into my google photos account, I will log out and see if it goes away.
    In firefox, logged out of google photos, and still see the picture.

  8. #8
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    Default Re: Resealing Lexan glass in a hatch I made

    Many new, production powerboats feature Lexan/ acrylic/ plastic windows set into fiberglass rabbet. No frame or stop. A line foreman at one builder I know said they use Sikaflex 295 for that job.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  9. #9
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    Default Re: Resealing Lexan glass in a hatch I made

    Pictures not visible in Firefox.
    The sikaflex PU and alcohol cleaning worked so far. It might not be the PU Sika recommends, but it is hard to argue with success. I think the backer rod was a very good idea. RTV glop-in-a-tube usually needs to be exposed to moisture in the air and will not cure well in a deep section, regardless of type or brand. It also helps with movement if there is a backer rod to give a more favorable geometry.

    Bonding polycarbonate is not easy. For the most part, some polyurethanes work well, but not all. To make matters more difficult, PC is sensitive to a number of solvents, such as acetone that will cause it to crumble. Something about recrystallizing the plastic that it becomes brittle after exposure. Loctite threadlocker causes cracks.

    From https://multimedia.3m.com/mws/media/...-tech-data.pdf
    3MTM
    Marine Adhesive/Sealant 5200 is not recommended fo
    r the installation of glass, polycarbonate or
    acrylic windows that are not also mechanically fast
    ened with a system designed by the manufacturer.
    Inconsistent adhesion of these unprimed substrates,
    specific design of the window, and movement due to
    thermal expansion and flexing, may cause application failure. It is strongly recommended that the
    customer contact the window/port light/hatch
    manufacturer for recommendations on proper sealing
    procedures.

    Other 3M caulking tube products: that are recommended seem to need a primer. There is a 2-part 3m Scortchweld 3532 that should work.

    Sika recommends sikaflex 295 UV with some precautionary comments about different brands of PC.


    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  10. #10
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    Default Re: Resealing Lexan glass in a hatch I made

    Sika 295UV is the industry standard for installing polycarbonate and acrylic panels. There are primers that should be used also. The link is to the application guide. Organic panels are polycarbonate and acrylic (lexan and plexiglass) Mineral glass is glass.

    The thickness of the caulking is important too thin and the expansion and contraction movement of the panel will break the joint. The length and width are the dimensions that are used to calculate how thick the caulk should be. On a resent job the panel was over 8 ft and required being spaced 3/8" from the frame.

    https://www.google.com/url?sa=t&rct=...dCfKXOFqfs5W-Q

  11. #11
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    Default Re: Resealing Lexan glass in a hatch I made

    I just use dolfinite anymore . Wax was working until it got too hot. All small windows though.

  12. #12
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    Default Re: Resealing Lexan glass in a hatch I made

    I put my 1/2 lexan windows in with Sika 295UV + primer. Worked great. The are set in a frame with a small gap between the frame and the edge of the lexan. There is about a 1" wide glueing surface in the frame.

    The safest place to stand in the boat is probably behind those windows!

    Glad to hear there is UV protection on the outside. Mine have no protection, biggest mistake I have made yet (that i know of ) . This is the result of direct sun after 5 years. With the nice bedding job in the Sika, they are not coming out. I'm going to try to polish them soon.


  13. #13
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    Default Re: Resealing Lexan glass in a hatch I made

    No pictures displayed here, using Chrome on an Android tablet.

  14. #14
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    Default

    Quote Originally Posted by ulav8r View Post
    No pictures displayed here, using Chrome on an Android tablet.


    I can see his pictures, using Tapatalk app on iPhone.

    Kevin


    Sent from my iPhone using Tapatalk Pro
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  15. #15
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    Default Re: Resealing Lexan glass in a hatch I made

    Quote Originally Posted by Jim Ragsdale View Post
    I put my 1/2 lexan windows in with Sika 295UV + primer. Worked great. The are set in a frame with a small gap between the frame and the edge of the lexan. There is about a 1" wide glueing surface in the frame.

    The safest place to stand in the boat is probably behind those windows!

    Glad to hear there is UV protection on the outside. Mine have no protection, biggest mistake I have made yet (that i know of ) . This is the result of direct sun after 5 years. With the nice bedding job in the Sika, they are not coming out. I'm going to try to polish them soon.

    Can't get em out? WTH , Lexan gets messed up , years fly by.

  16. #16
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    Default Re: Resealing Lexan glass in a hatch I made

    Generally speaking Acrylic holds up better than polycarbonate in marine environments. Polycarbonate with UV and scratch resistant coating may do better, but have been prohibitive from a cost factor when I've done estimates, more expensive than tempered mineral glass. I've never installed 1/2" Lexan (polycarbonate) and never seen the call for that kind of strength in a glued in application. Side panels in 50' sport fishing boats (10' X 3') have been tempered plate glass 1/4" (that is a different type of caulk/glue, but same process). I have made hatches and doors out of 1/2 and 3/4 acrylic but there was no additional frame around the panels.

    To remove the glass/plastic panels the caulk must be cut, much like automobile glass. Fein super-cut tool with knife/scraper type blade is what I use.

  17. #17
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    Default Re: Resealing Lexan glass in a hatch I made

    Quote Originally Posted by wizbang 13 View Post
    Can't get em out? WTH , Lexan gets messed up , years fly by.
    They will come out, but it would be a lot of work. Then I will have to clean the frames and bed new panels.

    The multimaster sounds like a good idea. I thought about working wire behind the lexan and sawing them out with a garrote.

    And yes 1/2 is definitely overkill. If I had it to do again, I would go with 3/8 acrylic.

  18. #18
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    Default Re: Resealing Lexan glass in a hatch I made

    I used 1/2 inch for my hatch. I bought the Lexan on Ebay for cheap. A prior owner had screwed acrylic on top and the acrylic plexiglass was cracked at the screw holes, plus was very cloudy, worn out.

    The Lexan I got had one side UV protection coated, which helps keep it clear. And It has stayed clear for many years. I ended up just remaking the entire hatch so as to drop the lexan into the rabbit without using any screws.

  19. #19
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    Default Re: Resealing Lexan glass in a hatch I made

    There are a couple of things that might help here for fogged plastic:
    Mothers polish plus 303 protection spray, (they only make a brief mention of 303 at the end): https://www.youtube.com/watch?v=A_yd1bbXswM
    3M paint protection film. Some videos look easier, thid one seems to need a steamer. https://www.youtube.com/watch?v=c6rcnMaR0sc
    Film, 12 mil
    http://www.3m.com/3M/en_US/company-u...2322949&rt=rud
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

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