To paint or not to paint.

[Ed Schenck]

Avid followers know that I recently had the bottom and keel soda blasted on my H37C. Now I am fairing and barrier-coating the keel. The bottom has(had?) five coats of barrier epoxy, I2000E. The boat is to remain out of the water until next spring for numerous reasons.

So I am wondering if I should put a coat of anti-fouling on her? It would make the boat look better obviously. But is it better to wait until 2012 with a new multi-season ablative(I am going to try Petit Hyrdocoat next time)? Or should I cover up the barrier-coat?

 

[Allan12210]

Ed,

Nice work. I would not put any bottom paint on until you are ready to put it back into the water. Start loooking now for bargains on the paint instead and keep it in the garage.

Make sure you pull the blue painters tape before it bakes on.

Allan

 

[Ed Schenck]

Thanks Allan. Paint is already in the garage. I had purchased a WM ablative on sale and realized it was not multi-season. Then I got two $10. coupons from WM at the same time that the Hydrocoat went on sale. Traded for zero dollars. And my tape comes off about thirty minutes after the last brush stroke.

 

[thinwater]

What is the conventional wisdom on soda blasting ...

... vs barrier coats? Althought it is not removed in general, it could have been made more porous and thus no longer anymore effective as a barrier than gel coat. I don't know. Would a single coat make sense, just to fill minor pores?
http://www.gcsodablast.com/marine.html
I see many posts on the web, but nothing authoritative. I'm sure it depends on the operator and his intent. I think I would give it a VERY careful look and then decide.

I saw your other post with the picture. Nice. Being a catamaran owner I have 32x4=128 feet of tape, but at least it's a bit straighter. It's ridiculus when I paint the boot top (256 feet).


Clearly the bottom paint waits until spring. Yes, some claim they withstand dry storage, but it doesn't help.

 

[Ed Schenck]

Seventy-four feet of tape per side is still no fun. Then again when I do the anti-fouling. So I am hearing that she should sit for the year looking ugly.

At what age does it stop making sense to spend days and days in and under the boat? And how do you quit? For very few dollars I can trade this boat for an almost new H27X, have it moved to where my Highlander lives, and have no maintenance.

 

[Steve Dion]

Ed: you may want to check with Interlux on the barrier coat to determine if it will hold up to UV. I don't think that they would normally worry about the epoxy being exposed for any length of time to UV so why would they try to protect the product?!

 

[Tim R.]

You really want to hot coat the last coat of barrier with your first/signal coat of bottom paint. Otherwise you will have to sand the barrier before painting next year. This will obviously reduce the thickness of the barrier and your adhesion will not be as good as hot coating now.

Wait til launch time to put on your regular AF paint.

 

[thinwater]

At what age does it stop making sense to spend days and days in and under the boat? And how do you quit? For very few dollars I can trade this boat for an almost new H27X, have it moved to where my Highlander lives, and have no maintenance.

Picture me with fingers in my ears. Please, quit talking sense.

 

[Ed Schenck]

Do you think that it matters that the bottom barrier-coat, now exposed by the soda blasting, is eleven years old? My thinking was that the gray barrier-coat would be my signal paint against the red anti-fouling. Won't I have to sand regardless of whether I paint next week or next year? It has already been over two weeks since it was uncovered. It is only the keel that is new I2000E with four coats left to go.

 

[Allan12210]

Ed,

Don't sweat it. The difference in adhesion will be minimal. These paints are so highly pigmented that adhesion isn't one of their strong points anyway. After the first monolayer it is all about cohesive strength of the coating and that is a lot less than the adhesive bond. So all you are gluing down is the first layer of particles and the binder surrounding them. The polymer used in bottom paint is not a reactive type so it is not a monolithic structure after drying. There is physical entanglement but not chemical bonding (i.e., crosslinking). Only if it were would it matter that much if it chemically bonded to the barrier coat...and in fact after consulting with the other chemist in the house (hence Alchemie) introducing a foreign object (bottom paint) into the top layer of uncured epoxy may actually interfer with its curing.

Next year just wash the bottom and scuff with a scotchbrite pad to break the gloss and dry it well before bottom painting.

After all the wet sanding I've done on the bottom in the last 25 years of haulouts there is no way any of that very first layer of paint exists and there has never been evidence of it letting go at the paint to barrier coat interface.

Thinwater, it is now safe to remove fingers from ears and move about the waterway. LOL

Allan

 

[Tim R.]

Do you think that it matters that the bottom barrier-coat, now exposed by the soda blasting, is eleven years old? My thinking was that the gray barrier-coat would be my signal paint against the red anti-fouling. Won't I have to sand regardless of whether I paint next week or next year? It has already been over two weeks since it was uncovered. It is only the keel that is new I2000E with four coats left to go.

I thought your original post indicated that you are fairing and then adding more barrier paint to the entire hull. My mistake.

 

[John Nantz]

Vote for "Wait"

Now that all the old bottom paint is gone - an expensive effort - I'd vote for waiting to apply the new paint for two reasons:

1. Toxicity: some paints don't like to be out of the water. The directions for the Pettit Trinidad SR that I use, for example, has a maximum time to launch of 60 days but it works better if the boat is launched shortly after application:
To Recoat To Launch
90F 2 8
70F 4 16
40F 6 24

So you might check the application requirements for the specific paint.

2. The second reason I would "wait" is to see what is happening in your state with regard to preventing copper bottom paints. If there is a move afoot to eliminate copper then you might want to change to a non-copper based paint to avoid having to strip the bottom again.

Here is Washington state they have banned the use of copper bottom paint and it may be that we'll have to strip all the old paint now if it contains copper. I haven't verified this but that's what I've heard. This will be an expensive process, especially for me because I've got a barrier coat that could be compromised.

 

[Steve Dion]

Ed:

This is from Interlux for your info.

"Yes, as long as the Interprotect 2000E is on the bottom it will be fine for several months. The Interprotect 2000E does lack UV properties therefore cannot handle direct sun exposure like on a deck or topside area.

Hope this helps.

Thanks,
Joe"

 

[Maine Sail]

Ed,

The polymer used in bottom paint is not a reactive type so it is not a monolithic structure after drying. There is physical entanglement but not chemical bonding (i.e., crosslinking). Only if it were would it matter that much if it chemically bonded to the barrier coat...and in fact after consulting with the other chemist in the house (hence Alchemie) introducing a foreign object (bottom paint) into the top layer of uncured epoxy may actually interfer with its curing.

Next year just wash the bottom and scuff with a scotchbrite pad to break the gloss and dry it well before bottom painting.

After all the wet sanding I've done on the bottom in the last 25 years of haulouts there is no way any of that very first layer of paint exists and there has never been evidence of it letting go at the paint to barrier coat interface.

Thinwater, it is now safe to remove fingers from ears and move about the waterway. LOL

Allan

Alan,

Hot coating the first layer of bottom paint to the barrier is strongly recommended by Interlux and in my own experience, and most every yard around here, it does make a big difference in first layer paint adhesion.

The boat I did back in 1997 still looks great to this day with zero lifting from the barrier coat. The first layer of copolymer ablative was hot coated to IP2KE per Interlux guidance and the results have been the best I've seen longevity wise. Our current boat was also hot coated but it has only been four years.

There are plenty of boats in our yard where the barrier was not hot coated to the last coat of barrier and the results can be alarming even after sanding & prep. One of those boats I watched get done. I saw the washing and sanding phases play out over a weekend day. I suspect he washed because it had been really rainy and there was deck pollution on the IP2KE. Less than three years later...... If one has the ability to hot coat I'd highly recommend it as Interlux does. Some times working outdoors this is not always possible with weather windows but I know it works very well.

Interlux says this:

Q: Is hot coating really that important?

A: Yes, staying within all of the specified overcoating windows when applying additional coats of InterProtect 2000E or from your last coat of InterProtect 2000E to your first coat of antifouling paint are absolutely important and it is best to follow them in order to ensure that you will achieve sound adhesion. As failure to do so, will result in detachment.


If Ed's bottom was blasted I would seriously consider another coat or two of barrier coat closer to launch time as the blasting could leave some porosity or thin spots in the DFT. Interlux seems to think exposed barrier on the bottom of a boat hauled is okay for a few months so I'd wait till closer to launch to do anything..

I am trying Hydrocoat this year and so far, other than ease of application, I have not been impressed with its ablating. I washed some foam and weed scum off the waterline and got ZERO paint on the rag. Not a good sign for an "ablative" paint!!! I will post more on that as the season moves forward.