Antifouling Coating Failure

[pcschmid]

I have an antifouling coating (cuprous oxide) over an epoxy base on a steel vessel. The AF was applied about 18 months ago. When the boat was pulled out of the water recently, most of the AF was gone (It was to be a 7-10 year system) and the AF is as hard as a rock, not soft as usual. Tried to lift with a putty knife and the AF crumbles into powder.

Manufaturer's data sheet says a small amount of thinner can be used (1 pint/1 gallon), but I don't think the applicator used any. I am guessing it is just a bad batch of paint (bad formulation).

Has anyone seen this before? Any ideas as to what would cause this type of effect on the coating?

Thanks in Advance

 

[0809]

Was it conventional (matrix soluble) type of antifouling paint?

 

[pcschmid]

Yes
It is an ablative coating

 

[Braddock]

It sounds like you are on the right track as to a bad formulation by the manufacturer. It is usually not beneficial to check the "retain" at the manufacturer plant as they always come back as formulated properly.

A sample of the applied coating can be sent for evaluation to a coatings laboratory and the results compared to the formulation. It seems to me that the binder in the AF was either wrong or absent and this could be varified by a lab. There is also a concern that the applicator mixed something with the AF that caused the problem. Some solvents or reducers can interfere with proper curing of the AF.

Including the manufacturer will be an advantage as they will want to know the reason for the failure also. They may also be willing to reimburse you costs for the re-application.

 

[corrosionman]

Is the AF a single pack or a two part coating. We just had a lot of remedial work to do because the men chose to mix a lot of small amounts and did poor guess work for the specified amounts of hardener. It is an on-going investigation but the effect was that the top coat was lifted from the inter coat by lots of hollow air filled blisters. Cheers CM