Blisters in barrier coat.

[lostsoul]

Originally Posted by Scrimshaw4

The best barrier coating that I have encountered, and used by many of the shops in the Annapolis area, is actually made by Sherwin Williams. It was originally developed for the Navy and restricted for application by certified pros and only available in large quantities. It's identified as follows and is available in 1 gal cans: Formula 150 Type III, N10V00350, Part A, #640182580 & Part B, #640182168. You can roll it on. I previously had 2000E and after 5 years it became osmotic and I ended up with a massive blister problem. Have this on since '07 and the bottom is dry! You can get it thru your local S/W retail store. Check your hull first with a moisture meter before applying to be sure your dry, sand bottom and then apply. JMHO

It is a bit funny, I need a hard coating to protect the gel coat to keep the boat fair during future sanding. I really dont need it to be water proof because I have the new vinylester bottom job.

I also wonder about how long the epoxy can keep out water. How many years? If it gets in, then it would take a long time for it to get out, I would guess.

[lostsoul]

Originally Posted by Suijin

I'll second the Sherwin Williams product. It's a commercial marine barrier coat...it's puke green, and it's less than half the price of the Interlux/Pettit/Etc. products. It's certainly cheaper than going the West Systems route, which will bankrupt you. That said, the last coat should be a barrier product by the same manufacturer of whatever bottom paint you're putting on, just to ensure compatibility.

lostsoul, if I'm reading your post correctly it sounds like you have epoxy on top of old antifouling paint. Is that correct? And you left the boat in the water for 9 years straight?

Personally, I would do one of two things A) do it right and take everything off, down to the gelcoat, and rebarrier coat it properly. I'd let it sit after being stripped for a month or two before reciting. B) Slap some anti-fouling paint on it and go sailing.

I think given the fact that you have this cluster$*%& of different coatings and filler in different layers that putting anything on top of it other than anti-fouling would be a waste of money and make any future stripping job all the more difficult.

Thanks for the reply. No I dont have epoxy over anti fouling, yuch.
The boat was peeled and relaminated with several layers of biaxial cloth and vinvyester resin. Then gel coat was put on that, I guess as a fairing compound.

Then after 7 years in the water I scraped and sanded barnacles. I decided to use epoxy to protect the gel coat, to keep the boat fair, buy applying epoxy. When you put epoxy on the bottom, it is automatically called a barrier coat. In my case That was really not my goal. I did not want to stop water ingress, the vinylester is not suspectible to blisters. I just wanted a hard primer. But I ended up with blisters between the epoxy (barrier coat) and the gel coat.

no cluster &^%$ here, LOL.

thanks for the reply. Sorry I was vague

[Bluemansailor]

Originally Posted by lostsoul

Blueman, what is the issue with micro ballons vs cabosil?

You also need a filler to thicken the epoxy into a putty. Select colloidal silica. Never use microballoons or any other hollow or absorbent (talc, for example) fairing compound to fill blisters.

Also cabosil has better adhesion .

[a64pilot]

Originally Posted by lostsoul

Sounds like my boat. Mine may have been wet. probably it was wet. At least the laminate is fine. I would not usually overcoat vinylester with epoxy but wanted to preserve the hull shape from future sanding.

I guess I will use another epoxy barrier for the same reason. What else can I do?

So far I have done nothing, just fly it and watch it
However the pox is subsiding, I theorize that over time the moisture is making its way out the inside of the boat, or maybe dispersing thru the hull?
I honestly have no idea what is going on, just the pox is going away, at this rate I do not expect to see any in two years for the next bottom job.

First bottom job I was prepared to have it fixed, guy at the yard said I'll take your money and do it if you like, but if its taken 27 years to get this way, then in another 25 or so they will need fixing, so I left it alone.
He didn't know about my theory of the barrier coat being applied over a not dry hull, just that it had pox.

[DeepFrz]

I'm not sure why gelcoat was applied after the barrier coat. Totally unnecessary and the source of your problem as the blisters are in the gelcoat.

[Suijin]

Originally Posted by lostsoul

I did not want to stop water ingress, the vinylester is not suspectible to blisters. I just wanted a hard primer. But I ended up with blisters between the epoxy (barrier coat) and the gel coat.

OK to answer your original question, I would just scuff up the epoxy patched blisters with 80 grit and go ahead and put down your antifouling. If you used fairing filler, like 407 or 410, I would probably throw a couple of coats of neat epoxy on the patches first, then scuff those up. As noted, balloon filler will absorb water, and I honestly would not trust any fairing filler underwater if it was not protected.

[ramblinrod]

Originally Posted by billdre

This situation as well as that of the OP seems to confirm an opinion of mine that has been criticized elsewhere in this forum. That is, if you have an older boat, mine is 1979, that doesn't have any blisters or other hull issues it makes little sense to then barrier coat it as an "extra precaution" against something that hasn't happened in the 30+ years it's already been in the water.

I agree with this 100%, with the following exceptions:

1. Always use a barrier coat as a thin film tie coat primer, between the sanded hull and antifouling.

2. If a boat had been in cool freshwater all its life and is being moved to tropical saltwater, put a barrier coat on it, even if it has never had a single blister.

When gelcoat is stripped or sanded off, in large areas or just bluster divets, it has to be dried out before being sealed. The fibres have to be sealed with neat epoxy. Then 1 coat of barrier coat primer, then faired with epoxy filler, then 4 coats min of epoxy barrier coat to at least .020" dry film thickness. (4 coats with a foamy will give you about 0.005" and use about 1/4 of the material of stated coverage. Ie, if you buy the recommended gallons, and when done have 75% left over, don't take it back to the store, apply it with proper coat thickness. Near "see thru" barrier coat doesn't do anything.