Micron 66 Blistered by Sunlight!

[Bev & Bill]

Hi Everyone,

We applied Interlux Micron 66 over older Interlux antifouling. Within 3 months following the boat sitting at a dock we found it necessary to haul out. Where the hull received direct 90 degree sunlight the paint immediately began bubbling and peeling off within minutes of coming out of the water. The final result is the antifouling on the upper part of the hull to within 3 feet below the waterline has peeled off. The area below that, not hit by sunlight while still wet, remains intact and solid. Where the paint has peeled off the old antifouling is clean and clear with no growth and no sign of oils contaminating the paint.

Can anyone shed any light on this?

Appreciate your thoughts.

Bill

[Jim Cate]

G'Day Bill,

Bummer! But my advice is not to ask us opinionated idiots, but ASAP call the nearest International Paint Co. rep. They are generally very interested in responding to this sort of situation, knowing full well the damage that a pissed-off customer can do these days... through forums like this one!!

Cheers, and please let us know how this pans out... that 66 is interesting (on paper).

Jim

[GordMay]

Micron 66 can be applied over Superyacht 800 and Superyacht 900 antifoulings in sound condition, with the use of a transition coat of Micron 55 or Micron Extra.

[Hud3]

Gord is pointing you in the right direction. What was the specific brand of Interlux that became the substrate? That's probably the first question the Interlux rep will ask. As long as the surface was properly prepped, it sounds like a compatibility issue to me.

I've used 66 with no issues. Good stuff, here in the Caribbean!

[Maine Sail]

I don't know what the salinity is up there but we had a similar situation here in Maine with a big East Bay on a tidal river. Interlux told them the salinty of the water was not high enough and is what caused the failure. It did a similar thing to yours, blistered when it came out of the water.

The unfortunate thing is Interlux does not state what the minimum salinity is, and for how long, and when I spoke with thier tech support they could not tell me either. All they would say is just that low salinity can cause a failure of the paint. I finally did eventually get a number out of them and it was 20 ppm if I am remembering correctly. I believe he said the open ocean is in the low 30 range

I was going to apply 66 when I just refinished my bottom but decided against it after talking with tech support because I spend about four days per season at the boat yard in this same river and a good rain could drop this boat yard below 20ppm.

I am guessing that the salinity in Vancouver is high enough but it may be a question they will ask..

[Hud3]

Interesting. I wasn't aware that salinity was an issue, but since the ablatives rely on dissolution of the copper to function, I can see how that could make sense.

I like the Interlux paints. I used Micron CSC and CSC Extra when we lived on the Chesapeake, and they worked very well. Salinities where we kept the boat ranged from 10 to 20 ppt. The ocean averages about 35 ppt.

[Bev & Bill]

Thanks for the useful information. We are currently having discussions with Interlux on the matter. We'll report back later. We are planning to clean off any loose paint and apply a barrier coat and in the future use a generic brand antifouling. For your information the boat is in Venezuela and during the 3 months following application the area was subject to unusually high rain fall and most of the peeling is within 2' of the surface which could reflect the comments from Maine Sail.

[fstbttms]

Originally Posted by Hud3

Interesting. I wasn't aware that salinity was an issue, but since the ablatives rely on dissolution of the copper to function, I can see how that could make sense.

All copper-based anti fouling paints rely on the leaching of copper into the water to function. I have never heard of salinity being an issue with any paint and most typical anti foulings (both ablative and modified epoxies) see use in freshwater and brackish environments. I don't believe that salinity is a factor in anti fouling performance. Not saying that it wasn't the cause of the failure of the Micron 66 bottom, just don't think it's an issue in general.

One of my clients is an Interlux rep. I'll run this past him and let the board know what he says.

[TaoJones]

Originally Posted by Bev & Bill

For your information the boat is in Venezuela and during the 3 months following application the area was subject to unusually high rain fall and most of the peeling is within 2' of the surface which could reflect the comments from Maine Sail.

Possibly, but I'd suspect it has more to do with the fact that a hull has less direct exposure to sunlight as it tapers down to the keel. The area within a couple of feet of the waterline is subjected to more direct sunlight than the "shadier" sections nearer the keel.

On the hard, the sun only shines anywhere close to 90* to the hull at sunrise and sunset if the fore-and-aft direction is oriented N/S, and the sun's intensity is least at those times. At its most intense in the early to mid-afternoon, the sun will be so high overhead that it is nowhere close to 90*.

If the vessel was oriented more E/W, then the blistering should only be evident on the side receiving the most direct sun exposure, if that is the cause of the blistering. It would be interesting to know the vessel's orientation, and whether it blistered equally port and starboard.

TaoJones

[hellosailor]

An uneducated guess is that the new paint was ot properly bonded to whatever was under it, and some moisture or solvent or air was present is small quantities, which then expanded from the heat of the direct sunlight, raising tiny blisters.

So while International will know best, the first question is what was under the Micron66 and what prep was done before it was applied? By who?

All it would take is, say, the guy on the next boat using some WD-40 and having a mist of that contaminate your bottom before the new paint went on, to cause a problem like that.

[Bev & Bill]

As promised, here is the response from technical support from the manufacturer and we hope this averts the problem for others:

"Unfortunately Micron 66 is a pretty unique product and can only be directly applied to Micron CSC, Micron Extra or Micron 66. If Micron 66 were applied over any other antifouling paint and was not properly sanded, cleaned and primed then I would anticipate seeing the Micron 66 peel/flake off the surface, exactly like what you are experiencing. The only other cause of the Micron 66 to peel/flake off the surface would be due to a surface contaminant. Your overcoating times and immersion times were within spec as well as type of application. Therefore it certainly seems to me as if there is a strong incompatibility between the coatings."