Which Sealant Should I Choose?

This is an often asked question which seems to have many different answers. Over time we have tried various sealants and have narrowed it down two primary products as our choice of sealant, 3M’s UV4000 and Boat Life Life Calk.

Boat Life Life Calk

Boat Life’s Life Calk provides a long lasting seal that stays flexible through out its lifespan. We find this product exceptional when it comes to bedding chain plates and stanchion bases, but is suitable for many other applications. Beware that this is a poly-sulfide and although it bonds well to most surfaces, including wood, aluminum and fiberglass, it can cause damage to plastics over time.

3M UV 4000

3M’s UV4000 is our product of choice for bedding almost everything else including deck/mast hardware and fasteners. This product provides an excellent adhesive seal that is great for a marine environment and is suitable as a general sealant in almost every application.

3m General Purpose Adhesive Remover

To clean these products, we first use a putty knife (or our rigging knife) to remove the majority of the mess. Next we will use paper towels and 3M’s General Purpose Adhesive Cleaner to break down any excess goop. Alternatively you can use acetone or mineral spirits as well. The trick is to make sure and do a final wipe using a clean paper towel and some solvent to remove any residual sealant, cloudiness or hazing. This last step will give it that professional, clean look. With bare wood surfaces or on non-skid it may be a good idea to tape off around the hardware to ensure a neat finished edge. DO NOT wait until these sealants have cured as this will surely result in a less desirable look and is more difficult to clean up.

Another Perfectly Installed Mast Boot

As much as I hate to say it, we do on occasion need to use a marine grade silicone sealant. The reason that, “I hate to say it”, is because silicone has to be the most overly and most  inappropriately used product in the hands of boat owners today. Silicone is only to be used for final touches before stepping a mast, i.e. any open electrical holes, cotter pin legs, or ring dings. We will also use use a small amount of silicone and 3M electrical tape to seal the upper ring of a mast boot (as pictured above). If you are sure that you need to use silicone sealant, and it is in the proper application, make sure that it is marine grade… household silicone will not work and may rot and mildew.

marine silicone sealant

Thanks for the read, feel free to leave us a comment or question below!

25 thoughts on “Which Sealant Should I Choose?

  1. We have had incredibly mixed results with 4000UV. It used to be pretty good but the last 8 years we have had multiple failures. They seem to have quality control issues and it is not worth using. Use good quality butyl tape (like that sold by MarineHowTo.com) to bed anything that is thru-bolted. It lasts and does a great job. We are going to move to from 4000UV to Sikaflex 295UV. Just can’t deal with the 4000UV failures any longer.

    1. Thanks for the comment Bruce. We did not notice this yet, but I believe you. We’ve been kind of on the Boat Life train….mainly because we can use a dab or two and the tube doesn’t become unusable.


  2. Thanks for sharing such great information about sealant, You have written and explained the different types of sealant, but you confused which types of sealant is best for you. This is for our opinion silicone sealant is best for you.
    On the topic “types of sealant” recently we wrote a blog (Here is the link: https://gtsealants.co.uk/blog/sealant-guide-types/)
    Sorry for the link but we thought it might helpful.

    1. Hi GT,

      The answer is there isn’t just one sealant for all applications. Typically we choose Poly-sulfides or adhesive polyurethane sealants for marine applications. Only in a few applications do we use Silicone. Having said that, as it appears you sell sealants, I am currently after a wood or brick colored silicone sealant that can be use in a harsh marine environment and stays pliable. Do you have any cartridges available for testing and how soon can we get our hand on a tube to try it?

      I may even add it to our article!

      Cheers and Thanks for the Read,

  3. I used 3M 4000UV to caulk my teak toe rail both at the deck and the outside.

    It has failed miserably:

    Makes a wet residue after rain or washing with plain water, sometimes
    feeling about like freshly laid caulk

    Peels off in strips, or

    Falls off in chunks [segments of the caulk line, complete]

    Crazes and chalks, and

    perhaps others related to cleaning with water (only) which I don’t recall,
    as the admiral does that.

    I called the tech support desk; that guy gave me the number for the head
    technical guy at 3M; every call resulted in being directed to voice mail,

    An extensive conversation, at long last after chasing each other around
    missing each other, with 3M’s head tech guy, Todd Jessen, established:

    My preparation (remove all old caulk, light sand in the chamfered opening I
    cut into it for deeper penetration into any gaps under the toe rail, blow
    out, scrub with acetone and allow to dry, tape toe rail and deck/hull) was
    as good as it gets

    Application was perfect (caulk, immediately tool with caulk tool, lift
    tape) – I had two people helping in order to do all this while it was fresh)

    Cure time and environment was appropriate.

    After which, he admitted that they had had a “formulation problem” with
    4000UV that they were still trying to sort out.

    He said, but has walked back that offer, that he’d provide a form for me to
    take to allow a merchant to be reimbursed, and that I should redo it with a
    competitor’s product.

    A variety of emails have passed, attempting to pin him down as to what we
    should do about that. He’s understandably reluctant to do that, but He
    wasn’t specific as to what to buy, other than saying he thought Sika had a
    good product for that application.

    But the fact that he told me not to go back with new 4000UV, free or not,
    that they were still working out kinks in the formulation, says volumes.

    That I’ve seen exactly my complaint in many places merely confirms that I am
    neither alone, nor inadequate in my use of the product. That he’d go to the
    length of telling me to buy a competitive product is honorable in the
    extreme, but I’m a bit surprised that he didn’t leap on the chance to have
    me present a good-fer (not even a mosquito on an elephant’s butt in the
    scheme of things for 3M) to make the ultimate tone of this a bit sweeter
    (“3M Tech Support Rocks! Details at 11!)

    So, when we again reach shore, we’ll be digging out all that soggy or
    brittle stuff, and starting over with something else. At this time, the
    ‘something else’ is under review, as not much of anything sounds good or
    without problems for the application we have (sealing a fiberglass-to-teak



    Morgan 461 #2
    SV Flying Pig KI4MPC
    See our galleries at http://www.justpickone.org/skip/gallery !
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    When a man comes to like a sea life, he is not
    fit to live on land.
    – Dr. Samuel Johnson

    1. Wow now that’s a thorough comment. Thanks for taking the time. A very interesting story. Sorry for the stroke of bad luck, it sounds like you tried your best.

      I will say, we’ve had nothing but success bonding 4000 to fiberglass and aluminum, but have had little experience using it on teak. To be honest it wouldn’t be my first choice for bonding wood to fiberglass. For hardware to teak applications (as we normally mount hardware on masts and decks)we use Boat Life Life Calk Black.

      I am surprised that he didnt recommend the next step up in adhesion…3M 4200 for deck fittings and rub rails (which are teak many times). First…I may look towards Boat Life, or even the old (tried and true) Dolfinite? How about Sikaflex?

      The only thing I can think may affect the adhesion of any product with teak is its oiliness….especially on its underside (gravity). Teak for that reason doesn’t even like polyurethane varnishes to stick to it, oil based one varnishes are usually the best here for straight wood to varnish. So maybe look for something with an oil base (which may be Dolfinite).

      I hope you find something that will get the job done. If you have the time, it would be great to find out what worked.


      1. Hi,

        This is not an adhesion (as in, keep something from moving) issue; anything more aggressive may make eventual recaulking destructives (pull off teak).

        The sika 292 is in the 5200 grade; about the only substitute for the intended use, vs 4000UV (or, at least that I’ve been able to find) is Boat Life’s Boat Caulk. We’d use white, but it shouldn’t make a difference (even though dark seems to do UV better than light; it’s never mentioned in any literature I’ve read on the product).

        So, I expect that’s what I’ll use. I will print out some of my emails and see if there’s any leverage with West Marine, along with returning an unopened tube I found during my reassembly of my KISS wind generator, which needed some caulk. As I am a regular at this particular store, the manager might do the deal and take it up with the rep on the next visit.

        I’ve posted this question/situation elsewhere; I’ll come back with the resolution.

        1. Right please do. “Falls off in chunks” does sound like it’s not adhering. I wonder if it’s acting differently against the fiberglass vs the teak?

          I’m willing to bet West Marine will exchange the unopened,unwanted product without much hassle.

          Keep us posted…


          1. I expect no issue on the unopened tube. I have reservations that I’ll get 7 tubes of somebody else’ product without charge…

        2. I could not manage to log in with Skip Gundlach, so I had to start over; it’s still me, with the followup; my apologies for formatting messes; this was taken from a previous posting in another venue:

          Much searching, talking with tech folk and the like, ensued, with
          Teak Decking Systems and Sika being finalists among many other

          Sika is too complex, BoatLife sent me “Bug letter #3” (boilerplate and
          referral to their MDS sheet) and the folks at TDS were very
          responsive, and
          entirely certain that their SIS440 would do the job. After all, it’s
          specific to adhering to teak (without any special treatment) and
          applied face up to the sun (so proven to be UV tolerant). So, they
          got the

          I did, indeed, get a case of TDS SIS440, and recaulked our toe rail.

          I’ve also had occasion to do repairs to some of the toe rail in the
          of replacing chocks, which were inset and causing leaks due to
          prep/carving of the inset for them in the manufacture almost 40 years

          I can thus confirm the assertions made by the tech guy at TDS that
          are dead simple. Cut out where you’ll be working and taper the
          ends. Prep the repair in the usual fashion – remove any material
          needed to
          get to whatever you’re repairing or replacing, sand, vacuum, blow,
          wipe with
          acetone, tape and recaulk.

          I use a simple rubber tool with three radii available, and blending
          into the
          previous caulk leaves NO evidence (other than a slight color
          upline as my acetone wipe only goes for a ways beyond the cut) that it

          And, I’m here to tell you, this is by far the most enjoyable caulk I
          ever had my hands on/in. Cleanup is literally a wipe with a paper
          (when wet, of course), though that won’t work on clothing – but it
          does work
          on hands and tools and everything else not fabric.

          It doesn’t drag, it doesn’t pull, etc., etc., that any other caulk
          I’ve ever
          used does. I no longer cringe when I think of a caulk job; it’s easy
          use, and easy to keep up with, whether in application, tooling or

          Pictures of our caulking techniques including prep and application can
          be seen here:

          Pictures of our blending in a couple of years later can be seen here:

          As this is specific to teak and fiberglass, and is used on decks where
          UV and wear is constant, I expect that I’ll get many satisfactory
          years out
          of it. It’s been a while since the original line went down, and it’s
          beautiful as it was that day, as well as cleaning easily with NO

          In a word, we love it.



          PS; it’s now years later and our love affair continues; it’s the ONLY above-water caulk I’ll ever use.

          However, for bedding stuff held down by machine screws or bolts, with backing plates and all that, there”s nothing better than the butyl tape formulated by, and sold by Mainesail…

          Morgan 461 #2 SV Flying Pig KI4MPC
          See our galleries at http://www.justpickone.org/skip/gallery !
          Follow us at http://groups.yahoo.com/group/TheFlyingPigLog

          When a man comes to like a sea life, he is not
          fit to live on land.
          – Dr. Samuel Johnson

  4. Have you tried ‘Life Seal’ ? made by same company, however it uses the poly sulphide and mixes in some silicone, keeps it bright, clean and makes a much nicer looking joint, equal to the finish of straight silicone but still has the sealing quality of Life Caulk. It’s my #1 choice for almost everything. AND if sometime down the road, you need to break that seal, it’s a lot easier than 3M adhesive sealants, which as we all know, can be murder to get apart.

    1. Hi! Thanks for the comment. And yes, I have tried Life Seal we use it as well. We consider it in the marine grade silicone category. I was under the impression that LifeSeal uses silicone and polyurethane? Life Calk, was the polysulfide, no? Do I have them confused? …totally could be my fault. I will look into it more.

      Thanks for taking the time. See you on the water.


  5. I see you have photos of an Oday 34 Stemhead plate. Mine bent by the anchor roller. I need to pull it off, have it bent back, re powder coated and set back in place. Is this hard to do. Do you all do this work? I am at Colonial beach, Va. Thanks Corey

      1. OK, I removed the stem plate and have emailed you all a work request via your web site. I am ready to send in the old and have you all build a new, then instal it on my ODay. I need to varify where to send it and to whos attn. Thanks Corey

          1. It turned out good. Very difficult to access, but all in all she looks great. Thanks for all the help and the fine job on the bow piece.

  6. What about Butyl tape.. I have had great success with this…This is what car manufacturers use around the windshields and not many of them leak.. easy to clean up and cheap.. I scoffed the first time I was told about this product… Now I use it when possible.


    1. You’re right Mike. I have heard many good things about it. We haven’t had a chance to use it yet and therefore have had no experience. I guess we have hard time parting with what works. Everyone is stating great results though. The only thing I’ve noticed is that it never looks quite clean, but that may totally have to do with the person applying it :-0). We will have to do some more experimenting with it. As well as, get more feedback like this, so thanks for taking the time to comment.
      We appreciate it!

  7. Thank you for the above info. After reading about the various sealants I came to the same conclusions; 3M 4000 UV or BoatlLife Life Calik for most applications. Rarely, marine grade silicone. So, I need to re-bed my stanchion bases. Why do you prefer Life Calk over 4000 UV for this purpose. Thanks again. Doug Pearce

    1. Glad to help. Either sealant, UV 4000 or Boat Life is acceptable for stanchion bases. The Boat life may remain a bit more pliable over time. I have certainly used both without problems. Thanks for the read and thanks for commenting!

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