The Holy Grail of Caulk - Does it Exist?

[Orchidius]

Hi there,

I recaulked my whole teak deck, stripped and repainted the steel toerails, stripped and repainted the cabin and stripped and revarnished all the woodwork. She sure is starting to look more like the classic she is, rather then a derelict construction site!

Anyway, I'm now facing an issue I don't think has a simple answer... It's one of those things where everybody you ask has a different answer, and is convinced theirs is right.

I'm looking for a caulk that can seal some cracks. Issue is that the cracks in question are between different materials, and in less than ideal spots. I'm talking about the gap between the bare teak deck and the painted steel toerail, the gab between the deck and the painted polyester cabin for example. It's virtually impossible to clear them of all old caulk, so apart from being different materials, the conditions aren't ideal for fresh caulking. Other examples are between some of the brightwork and the cabintop, and between the deck and some of its SS fittings.

What would you recommend using in this situation? It was my hope some magical product existed I could just caulk the corners with like you would a bathtub without having to worry about the dissimilarity of the materials and the less than ideal conditions. Now, I'm not too sure anymore though

[Orchidius]

I've heard mention of butyl in the form of tape, but it also seems to be available in sealant. Any experiences?

One of the hints I hear every now and again is MS Polymer. That any good?

It's a pain to research, since most of the info I find is from the manufacturers themselves... That's just not good enough as the sole source of information...

[ub1]

Dow corning 798. Used on the windows on high speed catamaran ferries. The # may have changed but the company has a good website. I have used it for 15 years, good elasticity and does not dry out.

[Orchidius]

What family of caulks would that belong to? I've never heard of it and I'll have to look hard to find a source here in Belgium I think .

If I can find the type of caulk I need for the job, I think I'll have it easier finding it with one of the big brands that are readily available. Surely they'll have their own version of it.

[Terra Nova]

Originally Posted by Orchidius

...

I'm looking for a caulk that can seal some cracks. Issue is that the cracks in question are between different materials, and in less than ideal spots. I'm talking about the gap between the bare teak deck and the painted steel toerail, the gab between the deck and the painted polyester cabin for example. It's virtually impossible to clear them of all old caulk, so apart from being different materials, the conditions aren't ideal for fresh caulking. Other examples are between some of the brightwork and the cabintop, and between the deck and some of its SS fittings.

...It was my hope some magical product existed I could just caulk the corners with like you would a bathtub without having to worry about the dissimilarity of the materials and the less than ideal conditions...

Fuggetaboutit! Slapping some caulk on the outside of a joint! Indeed!

The holy grail of caulking is not some magical product. It's elbow grease. Reef and clean the joint before caulking.

[Orchidius]

Trust me, its as clean as it will ever get without tearing out the teak. Still not as clean as I'd like to see a joint before caulking though...

There has to be plenty of situations in construction where it's simply not financially feasible to clean joints out perfectly before caulking... What do they use? If I had paid somebody to clean it out as well as I did (and I rented professional tools specifically for the job) it would've been a few boatbucks just for two clean joints on a 29ft boat. No way in life commercial setups **** about that much...

[appick]

I'll agree making sure a seam is good and clean is important. I can only relate my experiences. I've used both Butyl Tape and the type that comes in a tube for sealing windows and doors on homes.

I've used the Butyl Tape and have gotten no leaks after 4 years and sold the boat. The current owner still has no leaks. It was between fiberglass and teak.

I've used the Butyl Rubber in the caulk gun tube on my current boat. I re-bedded every deck fitting with it. The nice part about this is it is readily available at most hardware stores in the USA and comes in white. 4 years later no leaks as well. The stuff never completely dries so it always stays flexible and is able to take the movement between different materials. I've used it between bronze and fiberglass, wood and fiberglass, bronze and wood, Stainless steel and fiberglass. It's very sticky coming out of the tube and can make a mess, but it's easy to clean with mineral spirits.

I will caution that I've heard from some that using the stuff out of the tube is no good after I'd already used it. But currently I can say it hasn't been a problem for me... yet... time will tell. I feel like 4 years is a pretty good run so far.

[appick]

I forgot to mention the reason I used Butyl Rubber was that when pulling the hatches and hardware off, that didn't leak after 53 years, for the deck paint job the were all bedded with Butyl. I figured that to be a glowing endorsement for the stuff. It was still pliable and I could roll it into a ball and stick and pull it up to help in the removal.

[Orchidius]

I've read similar reviews of the stuff, and I'm more than convinced it's super quality. If I was actually rebedding anything in this rebuild, no doubt in my mind I'd go with butyltape.

The stuff out of a tube I have some reservations about though. For one, it stays sticky, how so? Say, hypothetically speaking (a), if I was to bump into the deck/cabin seam, would that smear the stuff all over?

Also, in applying silicone, it's easy to smooth the seam with a finger and some soapy water. Is it at all possible to get a smooth finish with butyl out of a tube?


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[jongleur]

Don't use Butyl if any of it will be exposed, as, like
you ask, it will get smeared all over. It's better
used for a joint that will be tightened mechanically.

Don't even think of using silicone. Don't. Forget it.
Silicone doesn't make a chemical bond. If it gets
worked, it will start capillary action and wick
moisture along/into the joint/seam. And, there is
no way to ever remove all traces of it and use
something better later. Why is it even still marketed?

[slowshoes]

Originally Posted by jongleur

Don't use Butyl if any of it will be exposed, as, like
you ask, it will get smeared all over. It's better
used for a joint that will be tightened mechanically.

Don't even think of using silicone. Don't. Forget it.
Silicone doesn't make a chemical bond. If it gets
worked, it will start capillary action and wick
moisture along/into the joint/seam. And, there is
no way to ever remove all traces of it and use
something better later. Why is it even still marketed?

+1 on exposed butyl - it will be a mess. I think silicone is the only sealant that won't leach the plasticizers out of plexiglass and lexan, so if your rebedding the glass in a hatch, it's the stuff to use. I agree though, not good for anything else.

[roverhi]

Use acetone to clean teak. The surface oils in teak inhibit bonding by all caulks. Wiping with acetone removes the oil and allows the sealant to bond and work long term.

Sillycone belongs in boobs not boats.

[Orchidius]

I was using silicone merely as an example for the way you can achieve a esthetically pleasing finish with some caulks. Wouldn't ever use it on the boat

So butyl is pretty much out of the question then...

Back to square one -.-


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[Terra Nova]

Surprised to be seeing no love for silicone. It is certainly one of the most useful boat caulks. Quite a few excellent choices of silicone based and polyurethane based caulks/sealants. The easiest to use are a blend of polyurethane and silicone.

Some products I regularly use:

Marine Grade Silicone
3M 5200
Boatlife Life Seal and Life Caulk
West Marine Multi Caulk
TDS and Maritime teak deck caulk
Sikaflex 296 (and others)
Butyl "tape"
Dolphinite bedding compound

Almost anything safe to use on boat windows will be silicone based.

[iancoombe]

I'm planning to rebed some deck fittings and was thinking of using a sikaflex product so I will be watching this with interest
S.V. Nereid
Currently anchored at the Parenthian island'
Malaysia