Paint Removal - Soda Blasting

[Bill Creadon]

I recently contracted with Mike's Soda Blasting for bottom paint removal on my Hunter 456. It took 7 1/2 hours of continuous blasting with 900 pounds of soda. The clean up was remarkable , as if they were never there. It cost roughly $50.00 / foot and I feel it was money well spent.

My next step is a little sanding at the waterline and then (2) coats of barrier coating and (2) coats of Petit Trinadad SR hard ablative in the spring. I would be interested on choices of barrier coat and bottom paint.

Bill Creadon
Hunter 456
Georgia Song

[HappyMdRSailor]

Hi Bill...
Welcome to CF!

Glad the blasting worked out so well for you... NOTHING is less fun than bottom prep...

Lots of threads here for bottom paint... The secret is to find out what's working in your intended cruising plans... location primarily...

For barrier, 2000e has been recommended by the guru's here, I've had fantastic results with it...
Interprotect 2000E Osmosis Prevention | Interlux

[Shrew]

Personally, I would choose the paint, then choose the barrier coat based on the recommendation of the paint manufacturer. I'd then following the manufacturer's recommendation as to the method of application and the number of coats.

Petit recommends 5-6 coats of barrier coat prior to painting. Technically you can use a different manufacturer for barrier coat (This is just on person's opinion). Note that even Interprotect recommends 1-5 coats. I would lean closer to 5, than 1-2 personally.

Petit recommends the following for Petit Trinidad SR:

http://www.pettitpaint.com/fileshare...rinidad-SR.pdf

Barrier Coat: Fiberglass bottoms potentially can form osmotic blisters
within the gelcoat and into the laminate. To render the bottom as water
impermeable as possible, prepare the fiberglass surface as mentioned
above (sanding method) then apply three coats of Pettit-Protect
4700/4701 Gray High Build Epoxy Primer or three coats of Pettit Protect
4100/4101 White High Build Epoxy Primer per label directions. Apply two
or three thin coats of this product. See Technical Bulletin TB-1000 for
detailed instructions.

[zboss]

Is the boat in the Northeast? If so - it may be too late in the season to paint the bottom. Temps and humidity have to be just right over a number of days to allow the paint to cure correctly.

If your boat gets hauled every season its recommended to use a single season ablative paint.

If you use Trinidad SR hard paint you will need to apply a new coat every time you haul out. If the boat sits too long you lose the SR part.

We have switched to West Marine PCA Gold Ablative multi-season over a pettit barrier because its cheaper, doesn't build up and doesn't require you to add a new coat every time you haul. We don't want to have to haul for two seasons.

[Suijin]

Sherwin Williams makes a commercial marine barrier coat that is less than half the price of Interlux or Pettit retail products. Comes in two five gallon buckets. However, you'll get the best adhesion of your anti-fouling if the last coat of barrier is the same brand as the anti-fouling you're going to put on.

I redid my barrier coat this past spring. Five coats of the Sherwin Williams product and then Pettit Protect and Trinidad Pro applied on the kicked barrier coat.

You definitely want more than two coats of barrier. At least four, and six is better. Some do even more. You do NOT want to have to take it down again.

[billdre]

For the sake of discussion ... I'm not sold on the need for a barrier coat every time someone takes accumulated bottom paint off their hull. Let me explain my perspective. First, I don't know how soda blasting leaves the gelcoat. After soda blastiing maybe the gelcoat is left more open or porous. If so then what follows doesn't apply. However, 4 years ago I took the built up bottom paint off my hull. Hand scraped it down to the gelcoat. Three weeks thank you. When I was done I had a few nicks and surface gouges. Beyond that the gelcoat on a 1979 O'Day was pristene. No blisters, no odd surfaces. If there's nothing wrong with it after 34 years why would it need a barrier coat now? So anyway, I put two coats of alternating color ablative paint, Pettit's Hydro-coat, on the hull. The boat gets pulled every fall, this is New England, and for the next two springs I just touched up the top ablative coat where it was wearing thin. Last Spring gave it a complete fresh coat. I won't go three summer's on one painting anymore but now I know for sure how long it lasts. Most importantly I'm not developing a hull with layer after layer of paint that's really not needed. In this case I don't think a barrier coat would have improved the hull at all.

[Suijin]

Originally Posted by billdre

For the sake of discussion ... I'm not sold on the need for a barrier coat every time someone takes accumulated bottom paint off their hull. Let me explain my perspective. First, I don't know how soda blasting leaves the gelcoat. After soda blastiing maybe the gelcoat is left more open or porous. If so then what follows doesn't apply. However, 4 years ago I took the built up bottom paint off my hull. Hand scraped it down to the gelcoat. Three weeks thank you. When I was done I had a few nicks and surface gouges. Beyond that the gelcoat on a 1979 O'Day was pristene. No blisters, no odd surfaces. If there's nothing wrong with it after 34 years why would it need a barrier coat now? So anyway, I put two coats of alternating color ablative paint, Pettit's Hydro-coat, on the hull. The boat gets pulled every fall, this is New England, and for the next two springs I just touched up the top ablative coat where it was wearing thin. Last Spring gave it a complete fresh coat. I won't go three summer's on one painting anymore but now I know for sure how long it lasts. Most importantly I'm not developing a hull with layer after layer of paint that's really not needed. In this case I don't think a barrier coat would have improved the hull at all.

You get away with it because you pull the boat every fall and it has the opportunity to dry out. Bottom paint is permeable, and so is gelcoat, so there is nothing to prevent osmosis. Also you only have three years of data as to how it's working out for you.

Barrier coat comes in different colors, and back in the 70's and early 80's a lot of it was white. You may have thought you were down to the gelcoat and were only at the barrier coat when you scraped it. It can be hard to tell.

Soda blasting can leave the gelcoat with a rough, granulated surface, even more porous than the original surface, and it's best practice to barrier coat. It serves, to a degree, as a fairing coat, particularly if you level it after a few coats.

Also, after three weeks of scraping (been there done that several times with various boats), or spending $2k to have it taken down, it's penny wise and pound foolish to not take the extra bit of time and expense to barrier coat the boat.

Lastly, the barrier coat acts as a primer for the anti-fouling if you apply the anti-fouling while it's kicking. You won't get anti-fouling flaking off like you often do with it on bare gelcoat.

[billdre]

Suijin posted: You may have thought you were down to the gelcoat and were only at the barrier coat when you scraped it. It can be hard to tell.

Soda blasting can leave the gelcoat with a rough, granulated surface, even more porous than the original surface, and it's best practice to barrier coat.

Suijin I wouldn't argue with anything that tends to open the gelcoat surface, so after soda blasting that sounds like one of those times.

My hull is a cream color so unless O'Day did the barrier coat as part of the final finish this hull's finish was absolutely continuous. So I'm sure I was "there." And it's not so much the 3 years in the water since but the 34 years before, that makes me think the rush to barrier coat in all cases is questionable. My understanding is barrier coating is a newer concept and wouldn't have been done in 1979 or around that time. This is a solid layup no core except the deck.

[Suijin]

Originally Posted by billdre

And it's not so much the 3 years in the water since but the 34 years before, that makes me think the rush to barrier coat in all cases is questionable. My understanding is barrier coating is a newer concept and wouldn't have been done in 1979 or around that time. This is a solid layup no core except the deck.

You've had the boat for six years. Unless you're intimately familiar with it's life during the prior 28 years, I think your anecdotal experience is poor evidence on which to question accepted best practices. Even then, It's just one boat.

[SVTatia]

Originally Posted by Suijin

...Also, after three weeks of scraping (been there done that several times with various boats), or spending $2k to have it taken down, it's penny wise and pound foolish to not take the extra bit of time and expense to barrier coat the boat.

Lastly, the barrier coat acts as a primer for the anti-fouling if you apply the anti-fouling while it's kicking. You won't get anti-fouling flaking off like you often do with it on bare gelcoat.

You nailed it!
Regardless of whether or not the boat is hauled yearly.

[Cadence]

Originally Posted by Bill Creadon

I recently contracted with Mike's Soda Blasting for bottom paint removal on my Hunter 456. It took 7 1/2 hours of continuous blasting with 900 pounds of soda. The clean up was remarkable , as if they were never there. It cost roughly $50.00 / foot and I feel it was money well spent.

My next step is a little sanding at the waterline and then (2) coats of barrier coating and (2) coats of Petit Trinadad SR hard ablative in the spring. I would be interested on choices of barrier coat and bottom paint.

Bill Creadon
Hunter 456
Georgia Song

It is nice to see at positive post.

[UNCIVILIZED]

Originally Posted by Bill Creadon

I recently contracted with Mike's Soda Blasting for bottom paint removal on my Hunter 456. It took 7 1/2 hours of continuous blasting with 900 pounds of soda. The clean up was remarkable , as if they were never there. It cost roughly $50.00 / foot and I feel it was money well spent.

My next step is a little sanding at the waterline and then (2) coats of barrier coating and (2) coats of Petit Trinadad SR hard ablative in the spring. I would be interested on choices of barrier coat and bottom paint.

Bill Creadon
Hunter 456
Georgia Song

I'm glad that this worked out for you. Might you please be kind enough to walk us through what led you to have the bottom media blasted. Meaning what questions you asked along the way, & of whom, that had you choose this removal method over others. And what you studied that you felt assisted you in making sure that the job turned out well. Sans goofs, of either removing too much, or not enough.
As such info may help others of us when it comes time to fully strip a bottom.
BTW, bet she lost some weight

As to the topic of how many coats of epoxy barrier coat to apply, I'm in the more is better camp. With say, a minimum of 3-4. Primarily due to what's written about how many layers of WEST System & similar is needed to seal a surface, post construction. And while I know that formulations are different, it makes sense to try & achieve similar fills of surface porosity, & top coat thickness over that.

Also, I'd be sure to read all that I could about a particular brand of product prior to applying it. In addition to talking to the paint's tech rep's/help. So that no problems in bonding between layers arises. Or between the barrier coat, & the bottom paint.

And, yep, as mentioned, ambient air temps sure can make a difference. Particularly this time of year, anywhere north of the tropics.


Edit: As to sealing post grinding or blasting on an old boat. There are definitely times when it's advised, even if the boat's been trouble free. Since when you fully strip a bottom, it's easy to wind up with the hull feeling like 60 - 100grit sandpaper. So that it's definitely more porous than it was previously. So perhaps more open to osmosis. Thus, sealing it's pretty cheap to do then, vs. having to strip it again later to fix water ingress, & then seal & repaint later. And barrier coat's cheaper per gallon than bottom paint.

[powsmias]

Originally Posted by Bill Creadon

I recently contracted with Mike's Soda Blasting for bottom paint removal on my Hunter 456. It took 7 1/2 hours of continuous blasting with 900 pounds of soda. The clean up was remarkable , as if they were never there. It cost roughly $50.00 / foot and I feel it was money well spent.

My next step is a little sanding at the waterline and then (2) coats of barrier coating and (2) coats of Petit Trinadad SR hard ablative in the spring. I would be interested on choices of barrier coat and bottom paint.

Bill Creadon
Hunter 456
Georgia Song

You might wanna take a look at this, not sure if it's been talked about but heard of it last year at annapolis show and like what i see.. any on this forum familiar with it?
Coppercoat Anti-Fouling Epoxy: much more than a marine bottom paint. Coppercoat is a multi-year bottom treatment for your boat or yacht. Save time, money, and haul-outs with Coppercoat.

[Clivevon]

Re Coppercoat. Yes, just had boat done for second time. First time lasted 10 years. However, epoxy is not totally waterproof andCoppercoat with its embedded metal granules isn't an effective barrier coat against osmosis. I lift the boat ashore for 2 to 3 months each winter. The Coppercoat is just a cost and labour effective way of anti fouling the boat. Saves a messy job each year and very costeffective with a10 year life. You can tell when it's failing- you will need to start dabbing on patches ofantifoulingpaintasitnearsits life end.

[steamgoat]

Bill,I would check with the blaster and see if he reccomends a fresh water pressure wash prior to painting.I know that failure to do this on automobile panels has led to paint adhesion problems from the soda. Bruce.