Deck recaulking with Sikaflex 290i - two seasons later

[MapisM]

Just in case anyone is interested in the background, back in Sep 2013 I posted this thread, before recaulking the main deck of my boat:
http://www.ybw.com/forums/showthread.php?373514

Back in those days, I was in doubt about whether to specify the Sika290 or the TDS440.
General consensus was that these are the two top products for this application, and I could expect both to perform comparably well in terms of durability.
Therefore, eventually I just decided to go for what my yard suggested and is used to work with, i.e. the Sika.
Btw, the previous recaulking was done in 2003 by another (excellent) yard in the Adriatic, with Sikaflex 290, and I only began to have a few (small) leaks after a decade.

The boat was put back in the water with the recaulked deck at the beginning of 2014 summer, and aside from some planks which were slightly damaged by a less than perfect removal of the old stuff, the job looked fine.
But unfortunately, during this season (i.e. after less than two full seasons!) I began noticing some leaks similar to those I had before the recaulking.
After a while, the leaks became even worse than before in places, and just by visual inspection I noticed that:
1) in some seams it's possible to stick a nail between them and the teak plank;
2) the caulking rubber seems cracked, as if it were much older than it actually is.
I am attaching below a pic of one area as an example, with an enlargement of a specific point.

I got in touch with the yard who did the job, and the manager agreed to repair the deck under warranty.
As a temporary measure, waiting to lift and store the boat at the end of the season, he sent some workers that masked the planks in the most evidently bad spots and sealed the caulkings with Sika291i, in order to stop the leaks - such repair was done one week ago, and so far it seems to have been effective.

But of course, I'm now a bit concerned again.
First of all, I can't understand the reasons for such fast degradation.
I understand that it's difficult to tell from one pic, but I'd be curious to hear your views on that.
Bad material? Missing primer? Poor cleaning? Anything else...?

Besides, in the previous thread that I linked at the beginning, there was a contribution from T00l00py, a new user at his first (and last!) post, who mentioned that in Europe the Sika 290 was not available anymore, and was replaced by the 290i, which according to him has a different formulation that is not as good as the old "non-i" 290.
And guess what?
When my yard did the job, not only they confirmed me that the 290 was not available anymore, but based on my indication, they double-checked with their Sika supplier, who "guaranteed" that the 290i was equally good, and that's what they eventually used.

Now, replacing the stuff with the TDS440 is the most obvious idea that springs to mind, but I fear that my yard might say that they don't assume any further responsibility if I "force" them to use some stuff they are not used to work with...

Any suggestions/ideas are welcome, thanks in advance!

 

[jfm]

Bad luck mm. This is becoming an epidemic. I have lost count of the reports I have heard of bad batches of sika product during last two years. Some batches are good, others not, people say. It sounds like bad control and consistency. One guy I know is about to have his third full re caulk on a 2013 boat of 24m. First was Saba, second sika and third will be Tds. I'm totally satisfied with my tds. I hope you get a good resolution to this.

 

[bluerm166]

Bad luck mm. This is becoming an epidemic. I have lost count of the reports I have heard of bad batches of sika product during last two years. Some batches are good, others not, people say. It sounds like bad control and consistency. One guy I know is about to have his third full re caulk on a 2013 boat of 24m. First was Saba, second sika and third will be Tds. I'm totally satisfied with my tds. I hope you get a good resolution to this.

You cannot blame the Sika 290 (presumably DC) unless you know what agents/degreasers etc. were used to clean out the joints ,whether the correct Sika primer was used in a dry joint free of contaminants ,was allowed to go off properly etc.or whether the correct separation tape was used.It is the combined system that should be considered plus the compatabity of any overall treatment to the deck which could attack the immature sealant.

 

[MapisM]

You cannot blame the Sika 290 (presumably DC) unless...

Hang on a minute.

First of all yes, I'm talking of the 290i DC - which as I said is, in my understanding, the latest/current version of the 290 DC that is not available anymore - sorry for not specifying the "DC", but is there another 290?

Regardless, I'm curious to better understand what you are trying to say.
I spent most of my working life in chemical companies, and while I'm not a chemist myself, I can perfectly understand your point on "systems" as opposed to "products".

BUT!
We are talking of a single component polyurethane, after all. I can't think of any application mistake that can change the behaviour of the product itself, to the extent of making it self-deteriorating.
I mean, of course the fact that in many places the material detached from the teak planks can be due to any of the reasons you mentioned - in fact, I did ask for views about that in my OP.
But as you can see in the above pic, it's also the material itself that broke down, regardless of its adhesion with the planks.
And that's after less than TEN month of sun/weather exposure (!), because the boat is sheltered during winter.
Oh, and since you mention deck treatments (something I agree that could be a factor, in theory), I never did ANY. I mean, not even soap - I only clean the deck with water, and not frequently either.
If you think this isn't enough evidence to tell that the product itself is to blame, can you explain EXACTLY why?

Just for further reference, I'm attaching another pic.
On the left you can see another point of the "new" recaulking, while the seam on the right is from the cockpit, that was not recaulked because, being less exposed, it was still in good conditions (and still is) when the deck was recaulked.
Now, the seam on the right was done with the 290 DC (rather than the 290i DC), and as I said it is less exposed, but it was done 13 (THIRTEEN, not a typo!) years ago.
Don't you think there's more behind such difference than a poor degreaser, primer, or whatever?!? :ambivalence:

 

[capsco]

The difference there is like chalk and cheese, so different in fact could it be a"Chinese " copy, if not must be at least a bad batch.

 

[BartW]

MapisM you scared me with your pics, as we did a lof of repaiers of our caulking, after the engine liftout, with Sika290i

reasons of the degradation that I can think of are,

a bad badge of Sika product
OR
there is a expiring date on the tubes, perhaps they used expired product (impossible to find out now)
also,
when we were filling the seams a few months ago, one of the local workers / painter, mentioned that the product's quality is sensitive for temperatute (don't apply in direct sun) en moisture,
actually its moisture that activates the hardening process, as explained in some technical info I had (I now nothing about the chemicals)

about the gap on the side,
that might have to do with NOT using a primer (Sika strongly recommands !)
nor
using masking tape in the bottom of the groove,

We know from experience, that some yards in Italy (Rome) are not used to use primer, nor the masking tape,
we have many of these side grooves since the recaulking project in winter 2011-2012 we replaced most of them with Sika

at that time in Rome, they used a two component caulking product, Italian brand iirc, don't remember the name, the product itself is still good no crack's at all, and not sticky.

did you asc Sika? they might have the answer ?

 

[itchenseadog]

MM, I sympathise with your predicament. As you will appreciate if will be very difficult to prove a bad batch (although your photo does look that way). As a retired boatbuilder who has caulked countless decks with many brands of caulking, I always used to favour the two part Arbocaulk which, if not mixed thoroughly, would produce something similar to your lefthand photo. When caulking pulls away from the teak, its an indication that either the teak was not degreased or more likely that it was not primed thoroughly. The job of priming is usually given to the youngest apprentice and if its not done throughly or if the caulking is not carried out wifhin the specified time, problems can occur. Proving a faulty batch or that something was done wrong will be a nightmare

 

[MapisM]

We know from experience, that some yards in Italy (Rome) are not used to use primer, nor the masking tape

I'm also aware of different views on the separation tape (depending also on whether the groove bottoms are cut on the sides of both planks or just on one), but I never heard of any yard that use the 290 without its specific primer - I'm pretty sure that my yard used it, anyway.

did you asc Sika? they might have the answer ?

No, I never had any contact with Sika, and TBH I'm not going to bother.
I guess it'll be the yard who will eventually complain with them, but my guess is that all they can achieve is a new supply of the product, which in the contest of a recaulking job is not the major cost component anyway...
...and frankly speaking, I'm not sure I fancy giving Sika another chance. :ambivalence:

 

[MapisM]

When caulking pulls away from the teak, its an indication that either the teak was not degreased or more likely that it was not primed thoroughly.

That would have been exactly my thought, if it weren't that the detachments began together with the signs of degradation of the caulking itself.
Don't you think that if the material consistency is poor and breaks down internally, it's much more likely also to not hold its adhesion to the teak/primer?
Regardless, the only possible course of action is bound to be yet another recaulking, I reckon.
And based also on other opinions I collected in the meantime, I think I'll insist with my yard for using the TDS stuff.
Which btw doesn't require any primer, so I think/hope that a preparation based only on cleaning/degreasing is more likely to be well made - touch wood...

By chance, are you (or anyone else, of course) aware of any specific care needed before recaulking with the TDS stuff a deck previously made with the 290 and its primer? Afaik the stuff itself is radically different, being polymeric (the first) vs. polyurethanic (the latter)...

 

[S57]

I can confirm that the issue you are describing is a problem with the Sika product. I just had the Sika representative on my boat yesterday to look at similar problems and he agreed to replace the Sika under warranty. They will supply new Sika and pay the yard to do the work.

I also know other boats that have had the same problem and Sika has paid to replace the product.

My big question is whether to replace with Sika again. My boat had new teak decks installed in 2014/2015, and at that time there were boats in the yard having their decks re-caulked under warranty. I was told that was because of a "bad batch" in 2013, but my boat has exactly the same problem and was done one year later. So what have they changed now? I'm not sure.

Some friends just replaced their Sika with TDS on a boat that had new teak decks installed one year before me. They also didn't believe that there is any evidence that Sika has fixed the issue.

So I suggest that you contact Sika, they should pay for the repair.