Bubbling Paint

saucedo80

Hello, I recently painted a wooden trellace. I primed all the wood first with an oil based primer (kelly moore 220 oil based primer) i gave it plenty of time to dry, i then went ahead and painted it with kellymoore 1250 exterior semigloss enamel upon the home owner's request.

I was called back due to the fact that some of the paint on the trellace was bubbling. I was surprised since i have never ran into problems of this sort. I went ahead and started to fix the damage. I began scraping away the bubbling paint and noticed that under the bubble there was sap. And as i looked at the rest of the wood there were spots where sap was just oozing out of the wood. so i went ahead and fixed the bubbling by cleaning off all of the sap, scraping, sanding and priming. i repainted the damaged spots.

it came out looking great, and it seemed like the problem was solved until early today, i took a look at it and there was the sap oozing out again and also some more bubbling.

well i have come to the conclusion that what is causing the problem is the sap, but how do i stop the sap from coming out? is there a special product or primer to stop this?

like i said i have never seen anything like this.

ProWallGuy

If its still bleeding sap, it was too fresh to paint. It should have sat, dried, and weathered more.

Best primer for sap or weeping knots is Zinsser's BIN shellac primer. But since its already painted, not sure what you can do for it.

Good luck :Thumbs:

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saucedo80

yeah, i know but the general contractor that built it wanted the lumber painted before the trellace was built.

Humble Abode

It seems like any general contractor worth his salt should have known about weathering wood...

That said you should take all the knots down to wood again and, like Pro said, prime them with Zinsers BIN or straight Shellac. You should still be able to see all the knots through the paint. That should keep you from coming back in a month or two.

Also I would talk to the GC about it being his fault for rushing you on the paint and see if you can't get him to cover some of your expenses... Good luck with that though...

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The NAPP
Milwaukee Painting Contractor

Teetorbilt

Bleeding knots will be a perpetual problem until they dry out. Nothing is going to stick to oozing sap. Attempting to seal it only aggravates the problem by denying it the air that it needs to dry. My advice is to let it season for a year and then come back and try again, large knots may ooze for years.

Next time build the trellis out of kiln dried cedar and start with an oil based sealer/primer or just let it go natural.

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