3 mth. old paint blistering


  #1  
Old 02-27-01, 03:55 PM
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I painted my exterior trim only 3 months ago. The wood is only 2 yrs old. I first lightly sanded it, then used Sears Weatherbeater oil based primer. I then waited a week and applied Sears new polyurethane exterior paint. I did 2 coats, waiting 1 week in between. I now notice large bubbles and peeling on the trim, and when I touch it, water actually pours out. What can cause this? and how do I remove the paint to correct this? Could it be the paint I used? Thanks.....
 
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Old 02-28-01, 06:52 AM
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This is a problem. I also dabble in sailboats and I just purchased a Westerly Nomad that has large blisters all on the bottom of the hull, pop the blisters and chemicals that can burn the skin comes out! My problem was caused by recoating over epoxie fillers or coatings that were not fully cured before re-coating, over time plus sitting in the water caused "acid" or chemical blisters.

In your case, seeing that blisters are filling with water I am going to say that water or moisture is getting into the wood somehow other than through the surface of the polyurethane, since it cannot penatrate the paint, it is getting traped in and thus causes blisters (one reason I recomend latex for exterior wood) Are these blisters more on the facia board? Or is it the trim around the windows, or all the trim?

When you pop a blister, take a piece of the polyurethane paint and look at the backside of it, is the primer you apllied still on the back of the paint or is it still on the wood of the house?

Read the label on the polyurethane, does it say anywhere on it as to what kind (if any) of primer to use and what it is compatible and not compatible with?

Post back with the answers and I will come up with a probable solution.
 
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Old 02-28-01, 10:24 AM
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The blistered wood is a trim piece over the front door and over the garage doors. The wood was originally painted by the builder 2 yrs. ago. The primer and paint I applied has stuck successfuly in 90% of the wood. It's only blistered along the top of the trim. When I remove the blistered paint, it is down to the raw wood, which originally was painted. The paint chips are smooth on the back side and the primer seems to still be attached to it. The polyurethane paint said to use a primer if wanted, but it was not necessary. It also said oil or latex primer was ok.
Thanks for your response.......
 
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Old 02-28-01, 07:27 PM
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Ok, the polyurethane and primer are holding well, so well in fact, that it is taking the existing paint off with it. Sounds as if the top of the trim is not caulked well or is old and cracked, letting water in, when the water turns back into a gas (moisture) it has nowhere to go so it pushes the paint out slowly causing a blister and filling up with water. What you need to do is pop and scrape off the blisters, cut out the caulking along the top of the trim and allow the wood to completely dry, this will take a while since the moister can only escape through the blister holes, and possibly the backside of the wood, a few days after the bare spots appears to be dry, recaulk the top of the trim with a PAINTABLE latex caulk, quikly sand the bare spots, spot prime the bare areas and allow to dry, spot paint the primer and allow to dry and re-paint the trim. Since the poly and other oil based paints will blister like that when moister is present in the wood it is very important to periodicaly check all the trim caulk and make sure it does not need repair. For future reference most exterior wood I paint I use latex for that reason, it is a lot better at keeping water out AND at the same time allowing moisture escape.

To answer you question about removal, you can do this with a paint stripper such as Bix or Strip-eze, it will literally peel the paint off for you and if you are wanting to cure this problem once and for all this would be one answer, following the directions carefully and re-priming and painting with a quality latex exterior paint, also fixing the caulking (if/where needed) in either case.

Hope this helps.

[Edited by Chipfo on 02-28-01 at 10:35]
 
 

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