Barrier Cover Over Keel Repair

[Me-and-Boo]

My boat is sitting with her keel repaired; the fairing compound needs to be coated before bottom painting. The fairing compound is the West System with 410 microballoons. I know I need to put a barrier coat over those before bottom painting.

Which barrier coat is recommended?

[boatman61]

I'd use West Epoxy over the whole keel after cleaning it down... 2-3 coats and then prime..
But others may know better...

[delmarrey]

Originally Posted by boatman61

I'd use West Epoxy over the whole keel after cleaning it down... 2-3 coats and then prime..
But others may know better...

+1 on that.

[s/v Jedi]

Yes, West System epoxy is just an expensive barrier coat. Scrub the fairing with plain water and scotchbrite to remove the amine blush; rinse well, I even use pressure wash. Follow up with a quick touch with 120-grit wet sanding, rinse again and let dry thoroughly. Brush or roll 3 layers of straight resin+hardener mix on the repair, adding next layer when previous is still sticky. When a layer fully cures before you are finished, repeat the scrubbing and sanding with plain water again. Also do that after last coat cured.

I have never seen a bottom paint that needs a primer on cured and wet sanded epoxy.

cheers,
Nick.

[minaret]

Do not use WEST as a barrier coat. Our yard did many boats this way before better products were invented, and despite the fact that we are experienced pros and were the only yard on the west coast offering a ten year warranty on epoxy barrier coat jobs, we still ended up doing a few warranty jobs. It's not a very good barrier coat, even with the additive, and it sucks to work with. It won't roll on fair no matter what you do, it will run and sag, which means more sanding. Proffesional yards haven't used this technique for ten years. Use Interlux 2000/2001. It's made specifically as a barrier coat, the micro-plate system is dramatically more effective. I've never seen a single warranty job in a 2000 bottom that was properly dried. It's much more user friendly, rolls out nice, and you have a two week window to catch the chemical bond, which means no sanding at all ever once you start applying barrier coat. You can even chemical bond the bottom paint to it, which not only means no sanding, it also means a much better bond. WEST is for those who don't know any better. It costs 3 times as much, takes four times as long to do, and will fail in half the time or less. We still use it regularly for fairing peeled bottoms, but always coat over it with 2000.

http://www.yachtpaint.com/usa/diy/pr...ect-2000e.aspx

[s/v Jedi]

Originally Posted by minaret

Do not use WEST as a barrier coat. Our yard did many boats this way before better products were invented, and despite the fact that we are experienced pros and were the only yard on the west coast offering a ten year warranty on epoxy barrier coat jobs, we still ended up doing a few warranty jobs. It's not a very good barrier coat, even with the additive, and it sucks to work with. It won't roll on fair no matter what you do, it will run and sag, which means more sanding. Proffesional yards haven't used this technique for ten years. Use Interlux 2000/2001. It's made specifically as a barrier coat, the micro-plate system is dramatically more effective. I've never seen a single warranty job in a 2000 bottom that was properly dried. It's much more user friendly, rolls out nice, and you have a two week window to catch the chemical bond, which means no sanding at all ever once you start applying barrier coat. You can even chemical bond the bottom paint to it, which not only means no sanding, it also means a much better bond. WEST is for those who don't know any better. It costs 3 times as much, takes four times as long to do, and will fail in half the time or less. We still use it regularly for fairing peeled bottoms, but always coat over it with 2000.

http://www.yachtpaint.com/usa/diy/pr...ect-2000e.aspx

Yes sure... This is just a keel repair that needs finishing, not a barrier coat. The repair area is now epoxy and does not need much protection other than from UV.

cheers,
Nick.

[minaret]

Originally Posted by s/v Jedi

Yes sure... This is just a keel repair that needs finishing, not a barrier coat. The repair area is now epoxy and does not need much protection other than from UV.

cheers,
Nick.

The OP specifically mentioned that he was looking for a barrier coat, and rightly so. WEST with 410 should not be left un barrier coated. And why it would need UV protection I can't imagine, unless he's not planning on bottom painting it.

[boatman61]

West Epoxy with black dye... no sags.. nice (to me) finish... did the whole boat with West...

[minaret]

Originally Posted by boatman61

West Epoxy with black dye... no sags.. nice (to me) finish... did the whole boat with West...

You must have reduced it quite a bit and spent some time tipping it out. Even so I'd bet I could find some drips and hangers, how about some close ups around hardware and rails? Reducing also creates much thinner coats, which defeats the purpose for barrier coating where millage is important. If you applied it that way to a bottom you'd need to do twice as many coats to get the same mils. Also that is a very bad idea, as WEST has no UV protection whatsoever, unlike almost any paint. UV will cause WEST to fail every time. That's why you cant use it for brightwork without applying regular varnish over it.

[s/v Jedi]

Originally Posted by minaret

The OP specifically mentioned that he was looking for a barrier coat, and rightly so. WEST with 410 should not be left un barrier coated. And why it would need UV protection I can't imagine, unless he's not planning on bottom painting it.

I read the OP again, but it clearly states that there is a repair done of the keel with epoxy which need some coating before anti-fouling. Even though the word barrier-coat is used, it is clearly just for the repair, not a normal barrier coating job of the hull.

My comment about UV is that UV is the only thing that can damage the repaired area. There is no gelcoat or polyester to protect, which is the target of barrier coats (to protect gelcoat and/or polyester).

cheers,
Nick.

[minaret]

Originally Posted by s/v Jedi

I read the OP again, but it clearly states that there is a repair done of the keel with epoxy which need some coating before anti-fouling. Even though the word barrier-coat is used, it is clearly just for the repair, not a normal barrier coating job of the hull.

My comment about UV is that UV is the only thing that can damage the repaired area. There is no gelcoat or polyester to protect, which is the target of barrier coats (to protect gelcoat and/or polyester).

cheers,
Nick.

In this case the intention is to protect the WEST with 410, not the gelcoat or polyester laminate. The OP clearly stated this. If you think epoxy is a sufficient barrier coat, why didn't you just tell him to bottompaint it and be done with it? How does more of the same product help? Personally I barrier coat every repair I do below the waterline, even on boats with no barrier coat. I have never had to do warranty work on a fiberglass repair, and I've done many thousands of them. Good barrier coating is one reason.

[boatman61]

Originally Posted by minaret

You must have reduced it quite a bit and spent some time tipping it out. Even so I'd bet I could find some drips and hangers, how about some close ups around hardware and rails? Reducing also creates much thinner coats, which defeats the purpose for barrier coating where millage is important. If you applied it that way to a bottom you'd need to do twice as many coats to get the same mils. Also that is a very bad idea, as WEST has no UV protection whatsoever, unlike almost any paint. UV will cause WEST to fail every time. That's why you cant use it for brightwork without applying regular varnish over it.

Sorry I cannot supply closer pic's... thats my 1st boat in '85...
It was fast cure and unthinned... just the black added to the second and third coats...
no roll and tip...

[minaret]

Originally Posted by boatman61

Sorry I cannot supply closer pic's... thats my 1st boat in '85...
It was fast cure and unthinned... just the black added to the second and third coats...
no roll and tip...

Nice! That's a much better pic. While I'm sure it's fine for your needs, I'm not sure too many people are trying to emulate that. It's certainly not what I'd call a pro finish. There's no hangers or drips because it's all one big roller stipple. I would not send out a bottom like that. Heres a pic of race bottom finished in our yard. And a pic of 2000 being applied. Compare.

[delmarrey]

West Systems actually has a UV resistant catalyst #207, which is supposed to be used with the barrier coat. http://www.westsystem.com/ss/assets/...nical-Data.pdf

WEST SYSTEM | Products | Product Selection Chart

[minaret]

Originally Posted by delmarrey

West Systems actually has a UV resistant catalyst #207, which is supposed to be used with the barrier coat. http://www.westsystem.com/ss/assets/...nical-Data.pdf

WEST SYSTEM | Products | Product Selection Chart

I actually worked with the reps from WEST while doing barrier coats for years. Aside from 207, they also recommend the graphite additive for barrier coating. It is designed as a fire retardant, but it helps in the barrier coating department as well. Still not even close to 2000 though. I mentioned the additives in a previous post. 207 isn't very good for UV resistance either, you still get solvent popping and "bridging". Even the WEST reps will tell you not to use it without overcoating with something more UV resistant.