Bleeding Sikaflex?

[nigelmercier]

For many years the Sikaflex between my teak boards has been bleeding; when it gets wet a black film develops that stains the surrounding GRP and clothes. Rubbing an area with a damp cloth produces a black stain on the cloth.

I assumed this was due to age, or a faulty batch, but I've since done the cloth test on several boats and they all do it to a greater or lesser extent.

Has anyone come up with a solution for this? I've been wondering about using an acrylic sealant, AKA quick-drying varnish.

 

[30boat]

Is it like a dry powder? I had that when I used regular Sikaflex on my windows and it was caused by UV light.

 

[pvb]

For many years the Sikaflex between my teak boards has been bleeding; when it gets wet a black film develops that stains the surrounding GRP and clothes. Rubbing an area with a damp cloth produces a black stain on the cloth.

Have you ever used chemical cleaners on the teak?

 

[nigelmercier]

Is it like a dry powder? ...

Yes, except when wet

Have you ever used chemical cleaners on the teak?

Often, but this problem started before I owned the boat.

 

[Yngmar]

My deck and other teak caulking does the same (interestingly also a 2000/2001 Bavaria), and I've ascribed this to the two-step "teak restorer" I've found in a locker when purchasing the boat. That stuff is pretty mean to caulking (acid based) and easily used incorrectly (the label said to not apply in bright sunlight and leave for a maximum of 15 minutes).

Also interested in a solution, although I fear that solution would be to scrape it out and re-caulk (at least in the annoying areas such as the cockpit trim).

 

[PCUK]

When you say Sikaflex, do you mean any unidentified make of polyurethane sealant or is it definitely Sikaflex?

 

[nigelmercier]

When you say Sikaflex, do you mean any unidentified make of polyurethane sealant or is it definitely Sikaflex?

Not sure, but perhaps there were not many in 2000.

 

[Billjratt]

UV degredation. the same happens to Avon rubber rowlocks which can then deposit on the hull if tied alongside.

 

[Adamastor]

Sika and some of the polysulphide solutions have loads of carbon-black to make them black. What happens is the PU binders break down and leave carbon dust as the insoluble residue.
Depending on the acreage of dead-tree decking, you may be able to rake out the seams and re-caulk with modern compound. I have seen people use splines stapled in place with a router to re-groove the teak, otherwise ye olde-fashion'd Seam-Rake and ye olde ylbowe grease should work in traditional fashion.

 

[nigelmercier]

UV degredation. the same happens to Avon rubber rowlocks which can then deposit on the hull if tied alongside.

That's what I assumed. So any solutions other than replacement?

 

[Adamastor]

That's what I assumed. So any solutions other than replacement?

Depending on the degradation, you could dress the seams with modern compound because Silyl polymers stick to most other compunds if they're prepared properly- think lots of acetone to remove degraded gungy compound.

 

[gjgm]

If it is not large an area, and only as a temporary fix, dusting talcum powder onto the caulking at least stops it smearing everywhere. There have been discussions over on MBC and suggestions of an alternative to the usual Sika caulking that doesn't seem so susceptible to this. I have had to re-do some smaller areas maybe three times, so I am getting a bit fed up with Sika.

 

[Stork_III]

If it is not large an area, and only as a temporary fix, dusting talcum powder onto the caulking at least stops it smearing everywhere. There have been discussions over on MBC and suggestions of an alternative to the usual Sika caulking that doesn't seem so susceptible to this. I have had to re-do some smaller areas maybe three times, so I am getting a bit fed up with Sika.

Hallberg Rassy use a Silicone caulking, 14 years on my boat and still fine.

 

[pvb]

Hallberg Rassy use a Silicone caulking, 14 years on my boat and still fine.

Yes, the silicone caulk is good - it was 24 years old when I sold my HR and was still stable and pliable.

But I don't think there's a "quick fix" remedy for Nigel's problem; it will probably be necessary to dig it out and recaulk to get a lasting solution.

 

[[29051]]

Our 2001 Bavaria did this from new. At first we assumed it was just loose stuff wearing off, and would settle in time. We later were told Bavaria had a faulty batch of Sikkaflex at the time. We were told some people had it recaulked as warranty work.

We never used any kind of teak cleaner on ours. The caulking got so shallow in places we were in danger of losing the teak, so we had it recaulked when about 8 years old. The new Sikkaflex did not bleed at all.

 

[nigelmercier]

Our 2001 Bavaria did this from new... We later were told Bavaria had a faulty batch of Sikkaflex at the time... The caulking got so shallow in places we were in danger of losing the teak...

Same thing I was told, but it's a bit late now

My caulking is proud of the teak by a few mm, some idiot (me) used a pressure washer on the teak. I sanded one panel so it was flush, but it still bleeds.

Any comments on using Acrylic Sealant?

 

[ashtead]

We always had problems with the black sealant on Bavaria from 2001 as stated it eventually became so bad we had cut out and replaced in worst parts by hatch and never had any issues with replacement sikaflex
I am not certain it was down to cleaning but due to inferior calking product used
Never found a way to stop the bleeding either apart from replacement

 

[Tradewinds]

Same thing I was told, but it's a bit late now

My caulking is proud of the teak by a few mm, some idiot (me) used a pressure washer on the teak. I sanded one panel so it was flush, but it still bleeds.

Any comments on using Acrylic Sealant?

TDS SIS-440 Teak Deck Caulking is the way to go IMO. I used it when I re-decked my boat.

http://www.teakdecking.com/index.ph...0-teak-deck-caulking-msds&catid=12&Itemid=107

Also recommended by JFM on the mobo forum.

There is a UK outlet
http://www.teakdeckingsystems.co.uk

 

[Yngmar]

Not a test of deck caulking, but still interesting to see that the go-to sealant of many on these forums, Sikaflex 291i scored poorly in a recent PBO test: http://www.pbo.co.uk/gear/which-adhesive-sealant-is-best-20877