Is this soda blast result OK? / How to finish job?

[gallilaw]

Just had the bottom soda blasted by someone recommended by several folks on more than one forum. Please let me know if the result is what should be expected.

I thought that the bottom would be cleaner.

I intend to use Interprotect 2000E and then ePaint EP-2000 as the antifouling. EP-2000 does not tolerate being painted over previous antifouling paints of a different type. If the Interprotect is put on properly there should be no problem -- unless the bottom isn't clean enough for Interprotect to adhere as it should

The blastman said that all the bottom paint was off and the patchy residue must have been from previous barrier coatings. He said he could not get the residue off, nor would that be expected of a soda blast job.

So...take a look at the photos and tell me what you think.

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I started sanding what's left, and it looks like I have a very long job ahead if I intend to get off all of the remaining crud. Other than sanding off the high spots and feathering the edges, what should I do to prepare the bottom for the Interprotect?

Thanks.

[scottyt]

its ugly but looks good to me. Run over it with a palm sander and 80 grit to give it some "tooth" and barrier coat away. make sure you wipe the hull down after sanding with a damp rag then let it dry.

[CalebD]

Hard to tell from the pics but I think that scottyt is right about wiping the hull down before attempting a barrier coating. I'd recommend using denatured alcohol or even acetone though instead of water on the rag.

The uneven colors on your hull could be the result of a previous 'barrier coating' using a product called Gluv-it which has been around for at least 20 years. Gluv-it dried sort of clear or opaque and could be the whitish residue on your hull. I'm not sure about the blue sections and red spots.

If the whitish residue is from a product like Gluv-it I'd first try scraping it with a razor or scraper to see if will chip or flake off. If it is still tenaciously sticking to the hull then just do as scotty suggested: 80 grit, wipe down and have at.
Good luck.

[fallard]

The large bluish-gray areas look like Interprotect 2000 that appears to be solidly adhered to the hull. You would need something more aggressive than soda blasting to remove it, but why bother.

ScottyT and CalebB have the right idea. If it passes the scraper test, you might apply the Interprotect 2000 in several test areas to verify that there are no compatibility problems. If everything looks good, use the 80 grit sandpaper, wipe it down, and apply your barrier coats. Make sure you read the directions for the 2000, because you can apply successive coats without sanding as long as you don't wait too long between coats. A little bit of planning can save you a lot of work.

[stormsailer1]

How long has the boat been on the hard? Check your moisture levels in a number of locations on the bottom. Make certain your moisture level in hull is very low before you apply barrier coat. Otherwise you "lock in" the moisture you're trying to avoid.

[gallilaw]

With the exception of the occasional red spot, that sands off well, all of the stuff remaining on the boat, as pictured, is stuck pretty hard.

My concern is that the edges between the patches are ragged but well defined; you can really feel when the higher blotch transitions to the smoother base below it. "Feathering" those edges will be tremendously time-consuming, and will still leave me with an uneven bottom. Smooth but uneven.

Will application of two or three coats of the Interprotect 2000 smooth the bottom sufficiently, or should I be using some kind of fairing compound before applying the Interconnect?

I had thought that "fairing" was done after filling in the occasional ding or crack or repaired blister. Is there some product that I should be using to fair the whole bottom so that the surface is "level" before I add the Interprotect?

Thanks.

[rayncyn51]

I tried to post some pictures of our results but was unable to figure it out.

Ours came out much cleaner, but we had nothing but anti-fouling on it. We will be coating the whole thing with a light epoxy fairing compund and sanding it off with a foam board. The first two coats of Interprotect get sanded again, then 4 more coats of Interprotect.

I agree with previous posters that what you have appears to be a n old barrier coat that is pretty well stuck to the bottom. Just leave it there and work around it. Whatever you use to fair will be softer than the stuff that is now on the hull, so it will be much easier to work that to remove what is there now.

If you want to see pics, pm me & I'll e-mail them to you.

The bottom line is that it’s not going to be perfect without an inordinate amount of time and labor. Smooth is good. Nobody will see wavy underwater. Pick your comfort level, get ‘er done, and go sailing!!

[sailingfool]

This does look like stuff you can cover, but given the work you'll be doing, I'd place a call to Interlux support and get their advice. You dont want to end up with a failed job. I have found them very helpful in the past, you should send them the pictures to review:
Technical Helpdesk
Tel: 1 800 468-7589
Email: iyp.us@akzonobel.com


I found Interprotect to not have much filling property, and expect that you will see your edges unless you remove the matrial or use a filler like an epoxy/microballon mix. Again Interlux should be helpful on this.

I dont think most blasting processes often give one a ready-to-cover, fair bottom. IMHO I would have expected/requested the blaster to remove the old barrier residue, and if you asked him to do that, you'd likely get a badly pitted gelcoat, again requiring follow up fairing. At least, that is my experience.