3M-4000UV

[JetStream]

I know this has been covered somewhere before but I was having a little difficulty getting answers through my search. I am planning a lot of re-bedding of stanchions, deck hardware and the like this spring. I had been planning to use 3M-101 polysulfide. I found that 3M has dropped that product and in doing a little research, I found that Thiokol has always been the only supplier of polysulfide and both 3M and BoatLife were just repackaging. Apparently 3M decided to drop it in light of having only one supplier and also as it seems to be a fading market. 3M is now pushing their urethane low strength adhesives like 4000 and 4200. It appears like the 4000UV might be a good replacement for those areas where I used to use polysulfide - any thoughts?
Thanks in advance.

[Hirilondë]

I use Sikaflex 291 which is Sika's low strength (half that of 5200) polyurethane. It has a bit more tensil strength than I wish sometimes, but I can usually forgive that for the other positive characteristics of a polyurethane. I don't know the 3M product first hand, but in general I think it is a good choice.

[Maine Sail]

I was very un-happy to hear of this and bought a few tubes of 101 from Hamilton in honor of an old friend. I always questioned Thiokol being the sole supplier as I found 3M 101 and LifeCalk to be somewhat different in properties such as thickness, smell and resistance to yellowing but each manufacturer could have supplied slightly differing specs.

There are two others you may want to consider.

Sikaflex 295UV = 160 PSI / 500% elongation at break (polyurethane) - Seems to hold up very well to UV and has a somewhat low bond, 3M 101 was only 30 PSI different.

Sikaflex 201US = 175 PSI / 550% elongation at break (polyurethane) - Not really marketed to the marine industry but is a good low adhesion polyurethane sealant and I have used it a number of times with good success. 3M UV 4000 & 4200 are both 300 PSI adhesion.

For deck hardware the 295UV would be my choice and of course there is still Life Calk..

[Hulukupu]

I've used 3M 4200 below the waterline with good success and Boatlife Life Seal for Lexan.

For stanchion bases, bronze portlights and the like I've used 3M 101 and have, as mentioned above, purchased a tube for next summer. It is still available from a number of sources. It is great to work with.

[Peter]

My caulk of choice is Sikaflex 291 Fast Cure. I find, for some strange reason, the Fast Cure seems to last indefinately after the tube is opened. Seal the end with a twist of electrical tape, and when it's needed again just persude out the little plug of hardened goop and away you go. I've managed to use it all the way to the bottom of the tube over a period of 12 months. That was not my experience with the regular Sikaflex 291 LOT (Long Open Time) or any of the 3M products.

I've used it on all my deck hardware, below the water line on the through-hulls, and on teak-fiberglass joints.

[sail_fix]

Tried the 4200 and have no complaints in particular, but over the last decade have changed over to Boatlife LifeSeal (clear) for all of our above-water bedding. Easier to work with than the 4200, imo.
Truth to tell, preparing the mating surfaces properly is probably more important then choosing the precisely "right" goo to use...
:)

L

[Hirilondë]

Tried the 4200 and have no complaints in particular, but over the last decade have changed over to Boatlife LifeSeal (clear) for all of our above-water bedding. Easier to work with than the 4200, imo.
Truth to tell, preparing the mating surfaces properly is probably more important then choosing the precisely "right" goo to use...
:)

L

I certainly agree with the preparation part. I am not so sure though that after dong a great prep job I wouldn't want to find the best goo also. I would not choose a silicone based product like Lifeseal. I have no doubts it works, but I can't live with the potential contamination of the silicone. A clear product is certainly tempting to use. But until someone develops one that doesn't use silicone in the formulation, I will live without it.

[Rachel]

I agree, Dave. I held back so I wouldn't be "the grumpy one."

Of course now I'm the second grumpy one.... ;)

All joking aside, I agree that the effort put into re-bedding fittings calls for the best possible (and most appropriate) compound. And no silicone (50% evil is still not good ;)

Rachel

[mobilchuckje]

If I may,

Tim, what material will you be using in the future now that 3M 101 is discontinued?

Cheers,
chuck.

[Tim]

I actually switched to Life-Calk some time ago. I started using it because it came in brown colors (good for bedding wood), and liked its working qualities, so started using the white as well. I haven't used 101 in several years.

[Idon84]

I'm using 291 LOT on just about everything. Have a several tubes left over from last year. Which brings up this question.

The tube says shelf life it 15 months. Is there a way of knowing if the stuff is still good or not? I would guess that if it flows out of the container well it should still be ok? Or would you just check the tubes and buy more?

Peter, Never tried 291 fast cure but your post makes sense. I'm going to have to try it. I probably wasted the equivalent to 3 tubes just last year because I couldn't use everything in the tube.

[mobilchuckje]

Vielen Dank!

[JetStream]

If you use Life-Calk polysulfide, is it worthwhile to use the BoatLife Life-Calk Primer that is recommended for good adhesion?

[Hirilondë]

If you use Life-Calk polysulfide, is it worthwhile to use the BoatLife Life-Calk Primer that is recommended for good adhesion?

I have never used the primer. I have used Lifecaulk on almost every material used on a boat except plastics. I have had no problems when the surfaces are properly prepared (scraped, sanded, cleaned etc.).

There might be materials for which the primer is necessary, or at least desirable, but I don't know of any. Maybe it can be used on plastics to resolve the compatibility issue? Although I would just use a different product instead of dealing with the primer step. Maybe it works to seal up contaminants that can't be cleaned? Now if it can seal up silicone then the developers deserve a citation and a raise.