Paint / caulk question

[Capt Kangeroo]

I have noted on my boat that wherever there is caulking such as door frames, fixed windows, etc., the paint is over top of the caulk and is cracking and flaking off. I know some caulk is paintable but is this proper procedure on a boat given the specialized expensive paints used? .....or should the caulk be applied after painting & left unpainted?

Whoever caulked it must have been an artist and I fear if I pull it all out I'll never get it so smooth and even again.

Anyone have any suggestions for the proper caulking to be used on a boat.

[Nomad Willy]

I think it depends on what kind of caulk and what kind of paint. And what got there first.

I caulk over paint but w high adhesion caulks I prefer to paint over caulk. And if you caulk over paint the resulting adhesion is never any better than the paint.

But painting over caulk frequently results in cracked paint as the paint is almost always less flexible than the caulk. I have an issue on my cabin top that is the opposite though but I think the crack is because of movement of a metal part attached to the cabin top.

What caulk to use is far more important to the task at hand than what paint. Most all paint works just fine (even house paint) but caulk comes in much more varied forms. I never use silicone calk as I had a ridiculous failure in 1970 something but found out (as I recall) that on glass and other non-porous surfaces it has very good adhesion.

So talking about what caulk to use is a much more valid thread than what paint to use.

For paint I use latex to 2 part (seldom 2 part though) and for caulk I use Dolphinite to 5200. Most often, however I use Interlux Brightside polly and Sika-Flex caulk.

[dwhatty]

Have used 3M 4000 with good results. Available in black or white. Not paintable.

[FF]

Calking is never forever , the home stuff is usually as good as so called Marine , esp at no load sealing.

Just read the tube and use paintable sealant , usually kitchen & bath.. 5200 is glue not sealant.

Or use Dolphinite where you can scrape off any that squeezes out , and paint away!

[Capt Kangeroo]

Thanks guys, it would be interesting to know what those on TF who have painted their whole boats have done? It may not look as good but seems to me removing the old caulk to paint then re-caulking over the paint might make for a better seal and eliminate the potential for paint failure?

Eric, your comment re silicone brought back a similar memory. In the mid 60's I had a wood plank Owens 32ft express. It was a beauty. Come time to recaulk the hull & thinking I knew better than the old farts & their old technology, I spent weeks pulling out the old oakum packing and bought a relatively unknown very expensive product at the time called silicone caulk. Must have used 200 tubes and many folks around the marina dropped by to see what I was doing. Come launch day as a crowd gathered and the Owens hung in the sling to soak the hull, usually 2-4 days, I proudly announced after only 5 min they could drop me in. There was not a drop of water coming in anywhere! I had revolutionized the hull caulking industry I thought rather smugly. Two weeks later I got an emergency call from the marina that my boat was sinking and immediately had it hauled. There was peels of laughter when it was lifted clear of the water with hundreds of long beads of silicone hanging off the hull everywhere. It was a bizarre sight to behold. Rather red faced I realized that when the planks finally took up water and expanded, they very effectively squeezed out nearly all of the silicone. The moral of this story for all younger folks is sometimes the old farts "do" know better, listen & learn. Now that 50 yrs later I'm one myself, it's my turn to sit back & chuckle at the foibles of youth.

[Larry M]

[QUOTE=Capt Kangeroo;276262]Thanks guys, it would be interesting to know what those on TF who have painted their whole boats have done? It may not look as good but seems to me removing the old caulk to paint then re-caulking over the paint might make for a better seal and eliminate the potential for paint failure?

When we repainted/re-gelcoated Hobo in 2011/2012 we removed all the caulk we could get to in part of the preparation for the refit. I couldn't see any other way. I didn't like the idea of painting over something that has a shorter life span then the stuff you're applying.

[RT Firefly]

Greetings,
Mr. CK. I'm STILL in the process of painting but I'm at the stage of deciding whether to caulk first then paint over or vicey-versy. OK, I lied. I've already decided to paint THEN caulk. I'll be using 3M 4000 in black and white (colors where appropriate) to seam cap rail to hull and rubbing strake to hull etc. To re-bed my fittings which were removed to facilitate painting and perform deferred maintenance, I'll definitely use Dolphinite having experienced success with the product in the past.Around windows and ports I intend to use Lexel (clear). I hope THAT works!
I will NOT allow silicone or 5200 in any shape or form on board! Allow me to tell you how I REALLY feel about silicone....

[TONTOROSS]

Has anyone tried BigStretch? I use it a lot from checking on logs to roofing here in Montana. Works great, paint-able, flexes & is water proof. I've not been around boats enough to know if it will work in a marine environment. That dolphin stuff works great. Comments?

[Scary]

Originally Posted by TONTOROSS

Has anyone tried BigStretch? I use it a lot from checking on logs to roofing here in Montana. Works great, paint-able, flexes & is water proof. I've not been around boats enough to know if it will work in a marine environment. That dolphin stuff works great. Comments?

Bottom line do you want to gamble on using $5 caulk when you are painting with $100 to $300 a quart paint that should hold up better than ten years. The prep and masking time on a boat is more like painting a car, not a house. The labor factor is a much larger component on a boat than a house. Not that there aren't boats out there that look like they have been painted with house paint. The problem is the cracks and chaulking you would overlook on a house would not be acceptable on a boat. Same with stretch marks in caulking. Sinkaflex and Lifecaulk have known results with marine paint. BigStretch and poly-sulfide caulk could be a cheaper way to go, you wouldn't really know until they failed. Latex paints are soft compared to marine paint.