Can you barrier paint over bottom paint ?

[OldManMirage]

So I've got a few blisters and I'm taking care of them. But I am just not going to have time or the ability to take the whole bottom down to gelcoat.

Is it ok - or even worthwhile - to barrier coat over hard bottom paint in good condition ?

I'm sanding it down to gelcoat where I need to but again - I just ain't gonna get everything.

What is the wisdom of the forum ?

[Chotu]

Not a good idea.

The slight contraction of the epoxy barrier coat upon curing will work to peel the paint. If it doesn’t peel, it will set up a continuous force on that paint that will make it prone to peeling. Then you’ll lose the paint and the barrier coat.

Better to do a patchwork job this time, if any barrier coat at all. Might even be best to save it for next time.

[sailorboy1]

Originally Posted by OldManMirage

What is the wisdom of the forum ?

I think it is a waste of money if you are thinking to buy more of the barrier coat. But to just use up a can because you made it up and it has to be used sure.

Remember to get bottom paint on it while still "tacky"

[OldManMirage]

The real question I'm trying to find an answer to is can you put a barrier coat over bottom paint.

If the answer is a hard no I need to know that.

[boatpoker]

A hard NO ! it ain't gonna work ... for very long.

[Chotu]

Originally Posted by OldManMirage

The real question I'm trying to find an answer to is can you put a barrier coat over bottom paint.

If the answer is a hard no I need to know that.

Hard no. I think I said that?

Gave supporting reasons

[catsketcher]

The reason it is a hard no is because you never, ever, ever paint epoxy over paint. It always gets bedded right into the structure because that is what is will become, part of the structure and laminate of the boat.

Paint aint boat, but epoxy barrier coat is part of the boat's structure and will last until your boat is landfill or you get in a grind it off.

So you can grind away the antifoul around the blisters now. Get right into the gelcoat. Then fill and epoxy barrier away (no paint). Then sometime later you can strip off all of the paint and you can re-epoxy even over the patches you are going to do now, no worries. That is not a problem at all, epoxy loves bonding to almost everything, including itself when well sanded.

You can probably tell I don't go in for any special barrier coat stuff - nice clear epoxy resin is good, lots of coats are good. You can add stuff in to make it even more waterproof, or just roll on another coat. Buy direct from the resin distributor - the price at marine stores for epoxy is incredible.

Say three coats of rolled on epoxy - wet on wet (tacky before next coat). Then 1 coat epoxy high build primer, then antifoul primer (rubber based paint dries in 10 minutes) then antifoul. Sticks really well.

cheers

Phil

cheers

Phil

[s/v Jedi]

Simply put barrier coat on the repairs you make. Don’t forget you need to put the antifouling paint on the barrier coat before it fully cures (fingerprint test)

[OldManMirage]

Yeah, this is all pretty much what I was thinking too.

So what I'm going to end up doing is patching the blisters for now and then - hopefully - next season plan a little better and take the whole bottom down to gelcoat for a proper barrier coat.

[sailorboy1]

Originally Posted by OldManMirage

Yeah, this is all pretty much what I was thinking too.

So what I'm going to end up doing is patching the blisters for now and then - hopefully - next season plan a little better and take the whole bottom down to gelcoat for a proper barrier coat.

Unless you have suddenly gotten a major problem I wouldn't strip the bottom of a 1980 boat, just do the spot repairs as needed. Boat life is too short and full of real projects to go looking for a long nasty unneeded project.

IMO

[Greatest Lakes]

Like everything else, anything worth doing, is worth doing right. Last winter I stripped my entire bottom with a 1" red devil scraper, used total boat barrier coat and total boat spartan multi season hard ablative.

I had probably 10+ layers of paint to scrape off. It was a lot of work, but I was able to repair and fair a lot of nicks, a few small blisters and prior owners shoddy repair work.