Soda blasting and barrier coat

shemandr · Jan 28, 2014

Having done one bottom there is no way I can think of that doesn't involve moving the pads. That is why its such a PITA. Not only do you have to get a perfect weather window, which doesn't really exist in the spring, summer, fall or winter, but you need to do it twice. Its impossible to do it ideally unless you have access to a climate controlled work place. Even then you have to compromise because the barrier coat needs to be cured before the stands are moved and the barrier coat done where the stands were. And there's the sanding. The bond between the two applications of barrier coat is probably fine but it isn't the homogeneous coat that we envision. Then you have to do it again for the bottom paint. Ugh!
However a smooth bottom is just required for a sailboat - period.

Sumner · Jan 28, 2014

Is the boat up on stands now? We went through this but also had blisters to contend with. Do you have that also?

We left the boat in the summer and returned about 7 months later. Right after we left we had the old paint sand blasted off by a guy that does it for a living on boats and has special equipement to do that that sucks the sand up as he goes. He left just a blush of paint on. Charged $1200 and the only one to come in under the bid price. I'd use him again.

Then the blisters were opened up and allowed to drain and dry. We were fortunate in that we didn't want to use the boat during this time and had plenty of time to let it dry. When that was done about December a yard crew did the blister repair and left the boat for us to paint.

Later I put the barrier coat on, 3 coats of Sea Hawk Tuff Stuff that goes on thicker than most and they recommend 2-3 coats. I put on 2 coats one day as it is better to go between barrier coats overnight vs. the bottom paint with their product. The next day put on one more barrier coat and then the bottom paint when it was still tacky. 2 different colors of that so I could see later when the first wore through. Then a 3rd coat at the water-line the same day.

Then we left the boat and it is like that. When we go back they will move the stands and I'll sand there and over into the barrier paint that is on the boat and then put on 3 coats of that and 2 bottom paint. That will be quick and easy.

You could do the same but wait a couple days before going in the water, move the stands. The yard can do that in a couple minutes. Paint where they were and go in the water the next day if you had too. If you pull the stands when they lift the boat and some bottom paint comes off just touch it up with more bottom paint. It will be fine. Some people put on bottom paint with their boat on its side in a bay when the tide goes out. It is pretty forgiving.

Don't over think it, I did and it wasn't necessary, just get the paint on in the window. You aren't painting the Mona Lisa, just rolling on paint. You just need 2 days to do it on a larger boat and maybe one with the right weather and help.

On our smaller Mac I got 2 barrier and 3 bottom on in one long day....

http://purplesagetradingpost.com/sumner/macgregor2/outside-39.html

..... and I'm not a kid anymore.

Good luck,

Sum

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Joe · Jan 29, 2014

Bottom paint will dry to the touch in a very short time, like an hour.... the application window between the final barrier coat and the first bottom coat is wide enough to apply the paint, move the stands, and finish it off.... read the instructions... it'll say overcoat when dry to touch or 1 hour etc.

The same with the barrier coat... as long as temp and humidity are within limits, you should be able to move the stands with each application layer... you can wrap the pads in plastic to keep the paint surface smooth. The application window should be long enough for you to easily do this.

What you might do is first paint the spots you'll be moving the pads to .....then paint the entire boat.. by the time you get finished the initial spots will be nearly ready for the stands.

Once you get the first layer of bottom paint on over the barrier coat... you can paint at your leisure... I have never sanded between coats ... the stuff is just not hard enough yet... besides.. all your sanding should have been done prepping and fairing before the bottom coat. Again... read the instructions.

Finally, since timing is important between barrier and bottom........ check that your copper based paint is well mixed... especially if it's been on the shelf a while.

Gunni · Jan 29, 2014

Have the blaster move the stands while removing the bottom paint. Then, when you go to coating, the most important aspect is building up the epoxy barrier coats while still tacky, depending on manufacturer you may need 6 coats. Don't worry about the jackstands. When you get all the barrier coats done, and apply your base bottom coat (while barrier is tacky) - you can then go to moving the jackstands and do the same process on those bare spots.

Use a good ablative, don't over-apply and you won't be doing this job again. I see a lot of over painted boats.

TLW · Jan 29, 2014

A barrier coat such as Interprotect will require 4-5 coats to be effective. The window between coats has been lengthened over earlier versions, and it is quite easy to get the job done correctly. The stands can be moved between each coat to assure a "seamless" finish. Alternately, a couple stands can be lowered a few inches on each coat - different ones on the next coat, etc. A little planning and all goes smoothly. See pics of this job from Summer 2013.

Contrary to some advice posted, the barrier coat is NOT built up while still tacky. That will get you into a gawdawful mess. Successive coats are applied while the previous coat is CHEMICALLY active, but dry to touch. (a thumbnail should not be able to scratch the previous coat) This is the WINDOW. READ THE LABEL.

Sumner · Jan 29, 2014

TLW said:
.... READ THE LABEL.

Yes I agree with that statement

, you need to see what the paint manufacture's application guidelines are.

For Sea Hawk's Tuff Stuff, what we used, they are:

Seal the surface with 2-3 coats of Tuff Stuff, or S-78 High
Build Primer. Apply the first coat of primer and allow
the surface to dry to become tacky. Temperature and
humidity affect the dry time, but you will know when
to apply your next coat of primer once the paint film
becomes “tacky”. You should be able to firmly press your
thumb into the paint film and leave a thumbprint without
any primer coming off the surface. You should use this
method in between coats of primer and your first coat
of antifouling paint. When applying over multiple days, it
is always best to go overnight between coats of primer
instead going overnight between the final coat of primer
and the first coat of antifouling. Additional information can
be found on the Tuff Stuff, S-78 Technical Data Sheets.

So they do use 'tacky' but others might have another word for it ,but as you stressed 'read the instructions'.

I chose Tuff Stuff after reading about it from someone on here and like it as it has a higher build per coat vs. some of the others so you need to apply about 1/2 the coats and I liked that. Is it a better or worse product? I don't know but the price was right and I didn't have to push the roller as much

,

Sum

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TLW · Jan 29, 2014

Sumner, thanks for the info on a product (Tuff Stuff) I was not familiar with. My remarks were regarding Interprotect and would be equally applicable to VC-tar (although I know it, too, has been reformulated)

The drawback I see with "tacky" products is the inability to move pads / straps during the process without leaving impressions and the Long time between coats using the overnight between coats. If it takes this long and still remains tacky, the whole job must take forever.

Interesting that the test instrument for both products is the thumb, but opposite results are desired.

Sumner · Jan 29, 2014

TLW said:
....The drawback I see with "tacky" products is the inability to move pads / straps during the process without leaving impressions and the Long time between coats using the overnight between coats. If it takes this long and still remains tacky, the whole job must take forever....

Well I agree with you on they shouldn't use the word 'tacky' as I don't really consider it 'tacky' as it doesn't lift at that point. I put the 3 barrier coats on and 2 1/2 coats of bottom paint in 2 days. We could of moved the stands the next day and painted where the stands were the same day and put the boat in the water the next day. They say tacky but the paint doesn't come off at that point.

Now I wouldn't want to do all the painting and then move the stands and then let the boat sit on them for days at a time. It might work or might not. The reason we decided to finish when we went back. If you painted and left the boat on the stands and were around or weren't I'd have the yard move them a couple times for a week or so, but that probably isn't needed. If in question call the manufacture.

Sea Hawk was very responsive to some questions I had and I had some of their paint for a year before using and didn't really like it as it had started to harden and they authorized the person I bought from to give me new paint at no cost. Again I had the paint myself for over a year so they weren't under any obligation to do that. I am happy with the product and would use it again and will keep using their bottom paint. At my age painting the bottom 3 times vs. 6 with the barrier paint was a real benefit

,

Sum

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Soda blasting and barrier coat

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