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Thread: Sealant comments please

  1. #1
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    Default Sealant comments please

    I was at the local Ace Hardware buying stuff. I bought a 2.8 oz. tube of "Star brite" marine silicone sealant. It claims to be good above and below the water line.

    I have been reading here that Sikaflex (sp?) is the good stuff but I was there and the price seemed right, about $6.00. I will be using it to seal around deck fittings. Any comments?

  2. #2
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    Default Re: Sealant comments please

    The synthetics work well for a time but, often, end up letting go. In doing so, they are also prone to taking wood with them creating more work for the repairer!
    I really like Dolfinite Bedding Compound. Hard to find now, it has to be smuggled into states that ban it. I don't know about your area but California is the worst place to obtain thre right stuff for a wooden boat!
    Jay

  3. #3
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    Default Re: Sealant comments please

    For hull fittings ( a.k.a., skin fittings) below the waterline. I prefer a polyurethane adhesive sealant. The most well known among consumer boaters of these is probably 3M 5200, but Sika and others make equivalent products. I like the adhesive qualities because;

    a. I don't plan on removing skin fittings often.
    b. These fittings may be subject to some stress from grounding/ trailering and I find the adhesive property good insurance on top of the mechanical fastening of the fitting itself.

    Like every thing else, choosing a goop is all about your specific application first, and then, secondarily, also about your attitude toward things.

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

  4. #4
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    Default Re: Sealant comments please

    Silicone products tend to leave a stick proof residue making rebedding problematic
    Good luck

  5. #5
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    Default Re: Sealant comments please

    Bedding Hardware With Butyl Tape (LINK)



    TL;DR
    #1 It never hardens and remains at the same thick consistency for well over 30 years.

    #2 Because it never hardens it always remains flexible.

    #3 It is multiples more flexible than a cured polyurethane.

    #4 It sticks extremely well to clean gelcoat, plastic, aluminum, bronze or stainless.

    #5 It's NOT a glue, and for through bolted deck hardware you do NOT need a glue. This thinking I know is contrary to the brain washing we have received by the polyurethane marketers like 3M, but it's true..

    #6 You can easily remove hardware bedded with butyl tape in the future without destroying your decks.

    #7 When you open a $16.00 - $20.00 tube of Satan's Glue or similar, and don't use it all, it quickly goes bad and gets hard. Butyl tape can still be used ten+ years later. I bought two cases back in 1997 or 1998 and was still using those rolls this past spring with no problems what so ever. That is a HUGE cost savings..

    As I mentioned butyl tape is VERY, VERY flexible. This photo represents well over 1000% elongation of the original squished thickness and the butyl is still stretching and much of it has not yet failed.

    You will also notice that it is still perfectly adhered to the deck and the cleat and never let go of either despite its very low 10-20 PSI bond strength. When compared to Satan's Glue/3M 5200 and its gelcoat destroying 700+/- PSI adhesion you can see why this ridiculous level of adhesion is 100% unnecessary.



    Here is a look at the below deck view of that cleat pictured above.

    This cleat had been bedded 29 years prior to this photo with butyl, and frustratingly, with no beveling of the holes. Despite the lack of countersinking/beveling it was used for 29 years covering over 50k+ nautical miles and never once leaked a drop. Butyl is an exceptional sealant and the deck, even after 29 years and 50k+ miles, was still 100% bone dry, not delaminated and confirmed dry with a moisture meter and soundings.

    You can see the pure white core and no signs of moisture damage.

    Last edited by sharpiefan; 07-18-2017 at 12:47 PM.

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    “What use is a house if you haven’t got a tolerable planet to put it on?”


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  6. #6
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    Default Re: Sealant comments please

    As noted above, silicon is evil. Throw it away and get something else.

  7. #7
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    Default Re: Sealant comments please

    I remember now that silicones creep invisibly and stealthily and will form an invisible coating that cannot be washed off and will prevent anything else to bond. I will return it.

    Thanks guys.

  8. #8
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    Default Re: Sealant comments please

    I bed just about everything with Sikaflex 291lot. You pay a bit more for it but a taped over open tube will last about a month (lot= long open time) And it is great stuff. The only issue is that it does not always take paint when fresh (the first season).

  9. #9
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    Default Re: Sealant comments please

    Fixtech is good and it lasts forever in the tube.
    My take is that if you poke someone with a sharp stick they'll get annoyed, if you smile and shake their hand they will be your friends.

    John Welsford

  10. #10
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    Default Re: Sealant comments please

    3M 4000 is also quite good. I even started using it on the shower stall in our bathroom because the hardware store calks wouldn't last. Never put silicone products on anything which you ever intend to paint or varnish. You can scrub it, sand it off, and even solvent wash the surface (or all three) and your paint or varnish will still probably fisheye on you in those areas.

  11. #11
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    Default Re: Sealant comments please

    Quote Originally Posted by Paper Moon View Post
    I bed just about everything with Sikaflex 291lot. You pay a bit more for it but a taped over open tube will last about a month (lot= long open time) And it is great stuff. The only issue is that it does not always take paint when fresh (the first season).
    Put the polyurethane tubes in the freezer, and they last forever it seems to me.

  12. #12
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    Default Re: Sealant comments please

    I have used dynaflex 230 for sealing deck fittings. Squirt onto screws and into screw holes.
    I just replaced my deck fuel fills and sealed to the deck with black dynaflex 230. Cleaned up excess with a rag and a little water.

  13. #13
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    Default Re: Sealant comments please

    Forget about using anything "to seal around deck fittings." Fittings must be "bedded," not "sealed around." They aren't bathtub seams. The fitting must be removed and the bedding compound (as Jay, I wouldn't use anything other than Dolphinite... if it can still be found) spread on the faying (faces that come together) surfaces. The fitting is then fastened and any excess bedding that squeezes out (as it should) removed with a putty knife (and wiped clean with mineral spirits if you use Dolphinite... Good luck with that if you use anything else! Mask instead.) You can squirt gunk and goop around the edges of a fitting all day long and you will never achieve any sort of really lasting seal, not to mention that it will look like crap.

  14. #14
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    Default Re: Sealant comments please

    Dolfinite.
    My local chandlery has it in THREE flavors!

  15. #15
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    Default Re: Sealant comments please

    Absolutely put the sealer under the fittings, and wipe off the excess. And I don't use any silicone sealers.
    Dolphinite will dry out and crack?
    My old boat someone had used it and there was this clay like hard dried out putty substance in various places.
    I figure it was a good 30-40 years old at least, whatever it was.

  16. #16
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    Default Re: Sealant comments please

    I just pulled apart some hinges bed in Dolfinite 40 years ago. Still soft and sticky. My sons dog found where I had thrown the rolled up chunk and chewed it like delicious gum.
    I re bed them with ...Dolfinite. WHITE designer dolfinite!

  17. #17
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    Default Re: Sealant comments please

    Quote Originally Posted by Todd Bradshaw View Post
    3M 4000 is also quite good. I even started using it on the shower stall in our bathroom because the hardware store calks wouldn't last. Never put silicone products on anything which you ever intend to paint or varnish. You can scrub it, sand it off, and even solvent wash the surface (or all three) and your paint or varnish will still probably fisheye on you in those areas.
    +1
    Only comment on this, NOT to argue with using 3M 4000, just a FYI: There is one hardware store silicone that will stick to the shower stall. It is GE-55 in a red tube and located with the plastic windows at Home Depot. They don't stock it with the rest of the caulks. It will stick well to acrylic and glass and did not peel like all of the others from my shower. It only comes clear and does not have a mildew inhibitor.

    Silicone for anything but bonding windows to metal frames is a disaster. The GE stuff worked in my shower, but I think you have to be careful to keep it cleaner than the mildew inhibiting stuff. Nothing will ever stick to a silicone contaminated surface.

    For caulking in place of Dolphinite (for when you can't find it or don't want a whole can), there is also Permatex #2 Form-a-gasket. It is a non-hardening, (but very stiff) rosin-clay-castor oil paste that cleans up with alcohol. Darker, smelly and harder than dolphinite. Comes in a tube at any auto parts store. Dolphinite is pretty much rosin oil, and clay too.
    EDIT cross post Sika 295 for windows.
    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.
    Last edited by MN Dave; 07-20-2017 at 11:39 AM. Reason: Permatex #2 corrected. not#3
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  18. #18
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    Default Re: Sealant comments please

    I didn't realize getting Dolphinite could be an issue. I've been able to get it on both coasts. Jamestown has it as does Fisheries Supply (Seattle)
    Steve B
    TraditionalSmallCraftAssociation
    DowneastTSCA.org

    TraditionalSmallCraft.com
    RIVUS 16' Melonseed

    "If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." E. B. White

  19. #19
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    Default Re: Sealant comments please

    Quote Originally Posted by Paper Moon View Post
    I bed just about everything with Sikaflex 291lot. You pay a bit more for it but a taped over open tube will last about a month (lot= long open time) And it is great stuff. The only issue is that it does not always take paint when fresh (the first season).
    I work in the RV game and I agree Sikaflex 291 is fantastic and pretty UV stable. We fit doors and windows with 291 and it works well for many years. I build my own camper about 9 years ago and it is still white and seals. Good gear.
    Cheers
    Reiner

  20. #20
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    Default Re: Sealant comments please

    Once I open a can of Dolfinite and use a bit, I spritz in a shot of "Bloxygen" and replace the lid using a mallet to tamp it down. The can then goes on the shelf "Upside Down"! I find I can coax a quart of Dolfinite into lasting several years or till the can is empty using this method.
    Jay

  21. #21
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    Default Re: Sealant comments please

    For bedding (not caulking), I use either Dolphinite/Boatyard Bedding Compound... or butyl tape. Depends upon the circumstances.
    David G
    Harbor Woodworks
    http://www.harborwoodworking.com/boat.html

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

  22. #22
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    Default Re: Sealant comments please

    Where does one get butyl tape? I've obtained rolls of it from metal roofing suppliers, but ithat was only about 5/8" wide. One thing to think about is that it doesn't drill--so I guess people are pushing the fasteners through it.

    ps I'm really fond of the stuff. Once it's stuck, it's stuck, but you have a few tries to position it if you lay it on a surface with no more pressure than it's own weight. Of course is stretches to infinity if it's too stuck and you try to move it. It also cuts really nicely with a razor knife if you keep the blade exactly 90 degrees to the surface it's on

  23. #23
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    Default Re: Sealant comments please

    Butyl tape is fairly widely available. Locally, West Marine has a small selection. Lately, they've been out, so I recently ordered a couple of rolls of 1/2" from: http://www.pbase.com/mainecruising/butyl_tape

    But RV places, and Amazon, have various versions: https://www.amazon.com/butyl-tape-ma...0tape%20marine
    David G
    Harbor Woodworks
    http://www.harborwoodworking.com/boat.html

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

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