Question on Repainting Keel After Bottom Paint Fell Off

[chouliha]

We are getting ready to haulout in Papeete to do a bottom job and other projects.

Last haulout (3 years ago) in Panama YC we ground the external lead keel back to bare lead and prepped it with solvents and applied 3 coats of Interlux Interprotect 2000 primer.

But in the heat I waited a few minutes to long to apply the bottom paint onto the almost dried primer. Within a few months all the bottom paint came off the lead keel yet the primer stayed on. Having been cleaning the keel on a weekly basis since.

Planning on sanding the primer real well to give it some tooth

Question: Should I roll on a few more coats of two part primer or just go over the existing sanded primer with bottom paint?

Your comments are appreciated.

Thanks

Chuck
Jacaranda

[David M]

Normally you can roll anti-foulant paint straight onto Interlux 2000 before it is cured and get somewhat of a chemical bond. Why did you apply a primer over the barrier coat and before the anti-foulant coat?

A primer might have been the problem. I don't know. Was your primer an epoxy? Dried is one thing, that can take a few hours, but cured is another thing where the coating is done gassing and is as hard as it is going to get. The fingernail test is a good way of telling if an epoxy coat is cured. Typically between coats you want dry but not cured, but there can be exceptions that you must check with the manufacturers to make sure you don't have chemical incompatibility.

I agree that sanding the now cured primer with something like 60-80 grit to give it a better physical bond would be a good idea. If there are portions of the anti-foulant paint that seems to be bonded well then I would not bother removing that down to the layer below it. Just knock off the outer surface of the anti-foulant paint so it is clean and leave it be...and then paint over it.

[chouliha]

I just used the barrier coat (Interprotect 2000) on the lead and then rolled the bottom paint right over that. BUT I waited maybe 15 minutes too long to do so and hence the barrier coat had dried too much and did not bond with the bottom paint.

It was very hot in Panama and I kept checking the barrier coat with my finger but must have waited a bit to long before applying the bottom paint.

The interprotect 2000 barrier coat has attached very well to the lead keel and shows no signs of coming off even after I have been scrubbing it about 2x's a month for the past 3 years. I am sure the power washer in the yard will be the real test

My question is after sanding the barrier coat with 40 grit do I need to add a couple more coats of barrier coat primer so it can bond with the bottom paint or can I just roll on the bottom paint?

Thanks

Chuck

[Captsteve53]

Chuck, please read the link https://doc.jamestowndistributors.co...nical_data.pdf

Actually when over coating after freshly applied the time is usually 5-9 hours for a chemical bond but if applying certain types of Antifouling you must wast 24-36 hrs!!

Any way the recommended sanding is with 80 grit and you should have no issues applying over the old Inter-protect, just be sure that water blasting was a thorough job!

Cheers Steve

[mitiempo]

Originally Posted by chouliha

My question is after sanding the barrier coat with 40 grit do I need to add a couple more coats of barrier coat primer so it can bond with the bottom paint or can I just roll on the bottom paint?

Thanks

Chuck

I would add at least one coat of Interprotect 2000 before anti fouling. If you don't you will have the same problem you had after Panama. Just apply it a bit sooner this time.

[Orion Jim]

Originally Posted by mitiempo

I would add at least one coat of Interprotect 2000 before anti fouling. If you don't you will have the same problem you had after Panama. Just apply it a bit sooner this time.

I agree. When I applied Interprotect three years ago the local painting pro advised me to apply the first coat of antifouling when there was no transfer of barrier coat to my thumb when pressed firmly into the surface. He felt this was a more accurate guide than elapsed time due to the variables of heat and humidity. His advice worked for me. No adhesion issues with my ablative antifouling so far

[chouliha]

Thanks everyone for your input. I brushed on 2 coats of interprotect after giving the old 2000e primers a good sanding. Because I sanded thru in a few small areas exposing the lead. I again sanded by hand using 80 grit after I already mixed the paint up and waiting the required 10-15 minutes. I immediately rolled on the interprotect. After the second coat I waited about 90 minutes (temp about 85-86) and also did the thumb pushed into the paint routine before rolling on the bottom paint. Hoping that this time around it sticks

Thank you again

Chuck

[rognvald]

C,
I don't want to start a war, but I always use West System for all my repairs. Whenever I had a failure in the past, it was with an Interlux product. They are easier to use, in many cases, but I have never had the results I wanted when I used their product. Contrawise, I have never had a failure with West System in over 30 years. Good luck and safe sailing.

[JPA Cate]

Chuck,

What a hassle. Man, I beg you're glad it's finished now. Time to start playing again.

Ann & Jim