Paint bubbling

[pennycar9]

We lifted the good ship Brigid Mary out last September as a few planks needed replacing. Whilst the shipwright was doing his stuff we got to grips with the antifouling and topside repainting. We noticed there was bubbling to the paint which was applied 18months previously.
The paint work was rubbed down and where the bubbles were, sanded down to the wood and allowed to dry out for a week.
A couple of coats of primer to the bare wood and then undercoats and top coats applied. Now I notice the paint is bubbling again. Any Ideas how this is happening and any remedy would be much apprieciated.

We Used an aluminium based primer, the under coat and top coat manufactured by Witham Oil and Paint Co. of Lowestoft.

 

[BlueLancer]

It sounds like a chemical reaction between the wood with the paint system you are using. I would suggest sanding down again and then seal the wood to provde a barrier between wood and the paint.Good luck

 

[sailorman]

Quote --
We Used an aluminium based primer, the under coat and top coat manufactured by Witham Oil and Paint Co. of Lowestoft.

 

[absit_omen]

Gribble - definately /forums/images/graemlins/shocked.gif /forums/images/graemlins/frown.gif

 

[Seanick]

I have seen this a few times, and have yet to understand the cause. Try sticking a moisture meter in the timber.
Alternativley it may be resin in the timber working its way out.
I have usede Witham Paints-very good!

 

[donncha]

Same thing happened to us when we used red oxide paint as a primer. The anti foul just kept bubbling, wasting a good tin and all. In the end we found the correct combination of paint by ringing international.

Make sure your paints are compatible, from reading your above post however I should see no reason why they wouldn't be.

 

[Gordonmc]

I had the same problem on the topsides of my mahogany carvel hull. When I first got the boat I used a random orbital sander on the existing topcoat and after filling the seams with putty applied two coats of Blakes primer, then two coats of Blakes enamel. All was fine until the first frost when a rash of bubbles appeared. The bubbles were not random but in patterns, different on either side of the hull.
The next repaint was in a fairly cold shed. Again I sanded down and noted that the bubbles were appearing under some of the original paint as well as paint I applied. From that I concluded it wasn't a primer reaction problem.
Because of other problems (the shed roof collapsed onto the boat) I left the hull unpainted for a couple of weeks. During that time I noticed fluid coming from the planking, showing as beads at the centre of each bubble.
I think what has been happening is that excessive moisture in the wood has expanded on freezing, causing the bubbling.
The couple of weeks without paint seems to have allowed the hull to dry as there is no repeat bubbling despite a winter on a mooring with some fairly harsh frosts.
I welcome comments on my experience, both to satisfy me that the theory is right and to suggest remedy in future.

 

[Mehlmann]

Definitely a moisture problem.

Find a friendly surveyor with a moisture meter or buy one from you local builders supply merchant and measure the moisture content of the timber. Should be less than 18% from memory.

 

[Cliveshep]

Sorry mate but reading about you worrying about bubbling paint and then casually mentioning the shed roof collapsing onto the boat............oh God, my aching sides! Must be the "silly season", I'm sure it wasn't funny at the time.

 

[Sixpence]

Seems there are a few of us with the same problem but incompatible paint isn't the answer. Entire upper deck was treated at the same time, after the same drying period, with the same stuff. Cockpit area has bubbled but no sign of it on the foredeck at all. Only clue I have is that the quarter birth paint is also bubbling, inside, which would seem to indicate damp from elsewhere getting in there somehow

 

[pennycar9]

Thanks for all your comments, seems the consensus is moisture.
The problem I have is if I sand back to the wood which is all sound and good, leave it to dry out for a few days, then all the seams open up a little and causes all sorts of problems.
I rubbed down a small part of the affected area a couple of weeks ago, and last weekend applied some primer, touch wood there is no sign of any bubbling as yet.

 

[Gordonmc]

I am glad to be the scource of some amusement.
The roof came down last winter... wriggly asbestos which fell 30 feet onto the deck of my boat and a mobo next door.
Leave aside the face I had just finished painting the deck, it happened over a holiday and the boat sat under a hole in the roof for some days before I demanded the yard shifted her to cover. By then rain had badly waterstained the stripped coachhouse timber and the whole boat was covered in crud washed down from the roof.
Hey ho.
It doesn't finish there.
The yard moved me next door to a steel tug. I just got the deck repaired and painted when the Polish guys started prepping for a paint job covering the decks in rust chippings.
What a larf.

 

[trebby67]

Sound like you have got oil in the wood