I am trying to repaint my house exterior over existing latex. I’ve scraped, sanded, rinsed with a hose, allowed to dry for at least a week and then primed the bare spots. My problem appears when I apply the color coat. On several boards within a day or so the paint bubbles up. When I scrape the bubble, I end up at bare wood, so it seems that the primer and color coat are bonding OK. There are no bubbles in the surface before the color coat.
I am using Sherwin Williams A100 (midgrade latex) for both primer and color. This has happened on a pleasant day that was in the high 70’s and not at all humid, and on a colder day in the 50’s with very high humidity. The spots that are bubbling are only the ones I brushed, I haven’t seen it yet on the ones I’ve rolled. All of the primer was brushed on.
I tried asking Sherwin Williams, and after saying “very weird” the guy suggested that I sand the primer and rewash. OK, I will do that. But that doesn’t seem to explain the behavior I’m seeing. Anyone can help me do this better?
Thanks.
Replies
I always use oil based primer on bare wood. I would try that next.
I've seen bad things happen when painting in direct sun. Paint surface dries before properly bonding to surface. Are you painting in the shade?
2 of the boards are in sunlight, 1 in a covered entry way.
I did only wash with water, and I sprayed from the hose, not a pressure washer, because I didn't want to drive the water into the wood. I could use TSP or something to clean all the surfaces before priming and again before painting. The reason for not using an alkyd primer is that I didn't go to bare wood on the entire house - just on the spots where the existing paint was not solidly adhered. Since I primed out over the edges of those spots, I thought it would be a mistake to put alkyd primer over the latex paint that was already on the house. Should I switch to alkyd?
Thanks very much for the suggestions.
Like I said, I've never had a problem with the alkyd.One note about a previous post of yours: Why two coats of primer? Certainly not needed, and it could cause problems.
Corporation: n. An ingenious device for obtaining individual profit without individual responsibility. --Ambrose Bierce
Only one coat of primer. It just extends over the existing latex paint in the feathered out areas.
I had read previously on this site that putting alkyd over latex was a bad idea because the latex flexes more than the alkyd.
There is a sign at my local paint store that always makes me chuckle.....
"THE MOST COMMON PAINTING PROBLEM IS COMMON PAINT"
I put down the Sherwin Williams and Ben Moore for Pittsburgh. They came out with a line a few years ago that I swear by. The Manor Hall line and specifically their "Timeless" exterior latex is the most amazing paint I have ever seen. NO PRIMER REQUIRED AND I HAVE PAINTED GLASS WITH IT. The money it saves on labor makes it worth its weight in gold. It covers better than anything on the market and resists fade better than anything I have seen. I went back and touched up a graffiti mark 2 years later and you couldn't even see it (even with a pounding western exposure). Another great product is their Manor Hall interior semi-gloss latex. It sticks to oil with no primer required and when dry it is hard to tell where the latex starts and oil stops. The moral is always buy the highest grade paint. I think there was an article in FHB about that very point recently. I know you can buy house paint for under 10-$15 a gallon but is it worth using???? If the highest grade is $45 a gallon, and it extends the life of the paint job for even 2 or 3 years (Probably more like 5-10) isn't it worth it??? Combine the labor savings of no primer with the extended life and that 40-$60 for the highest grade paint becomes a bargain. Especially at my own home (I haven't figured out how to get paid for HOMEWORK).
Just my .02
You say the bubbles consist of both paint and primer and leave bare wood under them when scraped off. Question: Are these bubbles occurring where you had scraped to bare wood and applied latex primer on it, or are they occurring where you applied primer over old paint and then painted over the primer?
If they only occur where you had gone down to bare wood, then the latex primer isn't bonding with the wood. That would indicate either a failure of the primer itself or problems related to substrate preparation.
If, OTOH, the bubbles only occur where you applied new primer over old paint, then you've got some serious moisture in the wood which is blowing the entire 3- or 4-coat-thick paint film off the substrate as it heats and expands.
Someone else suggested you get the manufacturer's technical rep out there to put actual eyeballs on the problem. I second that advice. Any reputable paint manufacturer will send the rep out at no charge.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
What type of wood?how old is the house?Did you add anything to the paint?When you prepped down to bare wood did you use sandpaper? what grit" did the wood look burnished?Assuming the week after you washed the house down was sunny, was there any heavy dew or rain after you primed?if you feathered the edges down far enough, a little oil primer should not hurt, on an older house you are probably down to oil anyway.I think using the topcoat for a primer wasn't a good idea. You are describing blisters not peeling? Blistering is usually a case of moisture from one or another source. from your description neither day seemed overly hot and one location is under a porch, so no direct sunlight?
Barry E-Remodeler
Thanks everybody for all the great ideas.
To answer a few questions: I am using the primer that goes with the paint. They both have the same label on them (A100), but one is labeled "primer" and the other paint. I haven't added anything to the paint because I am brush and rolling, not spraying.
I'm not sure whether the bubble spots are where I primed or not. One I'm pretty sure the answer is yes, the other 2 boards I'm not so sure.
It is getting cold at night, but not below freezing. We live in the desert, but we did have rain this weekend, so it is possible that there was still some moisture in the wood for 2 of the boards, but the other one was painted on a sunny day after weeks of no rain. That one the bubbles showed up within hours. It is a west facing wall, so the afternoon sun was on it.
This paint is not cheap. It is $34/gallon, and I think more expensive paint would be wasted on me if I can't figure out my prep/application problem. This problem has happened in 3 places on the one side of the house. The other parts I've done look fine. The weird thing is that it is only happening (so far) in spots where I've brushed, the rolled on are OK (so far).
I'm going to give these spots another try. If that doesn't work, I will call SW and ask to have the rep come look at my prep.
Thanks again.
Paint can blister from the sun, but the vast majority of blisters are from moisture. It might be from interior moisture rather than liquid water entering from outside.
Some older houses that lack moisture barrier in the basement/crawl/slab have significant amounts of water vapor that has to go somewhere. You mentioned it gets cold at night. When water vapor is working it's way through wood to the exterior what happens when the temp falls? Condensation. I've heard of houses that have to have the siding wedged apart to allow enough moisture to pass around boards before blistering would quit.
My bet is your problems are moisture related. Yep.
Beer was created so carpenters wouldn't rule the world.
The weird thing is that it is only happening (so far) in spots where I've brushed, the rolled on are OK (so far).
Brushing makes a thicker film so you already know the solution to most of your problem--brush a thinner coat.
Beer was created so carpenters wouldn't rule the world.
Brushing makes a thicker film...
Maybe it depends on technique, but in my experience, rollering makes a thicker film than brushing.
I can put it on too thick with either method and make it run and drip.
Good point! I must be a "heavy brusher" and a little light on the roller. :-)
Beer was created so carpenters wouldn't rule the world.
I was thinking that maybe I was laying it on too thick with the brush. So my plan now is to lightly sand the primered spots, wipe down with a damp rag, paint with a thin coat and hope for the best.
Instead of just the sales guy, you might request that the SW local rep meet you at the job site and discuss the fix. After all, you're using their paint to their specifications -- they should be able to diagnose why their paint isn't sticking if you're using the correct application on the associated substrate.
Otherwise, find a new paint supplier.
Oh, I would agree with the "oil based primer" suggestion as well -- that should be your next easy step before going crazy. Or on those tough spots (if it is isolated for some reason) you might try a primer / sealer like BIN.
Did you clean the surface prior to priming with a degreasing solution, or just pressure wash. usually just a pressure wash would suffice, but clearly you have more than meets the eye...
I use Bennie Moore Moorewhite (alkyd) for priming and have never had a problem. Never had good luck with latex exterior primer.
I've had the same thing happen to me on a balustrade. I thought it was moisture in the wood so I scraped the peeling stuff down to bare wood and let it "air" out for several months. I've double primed with oil and covered with two coats of latex. . . . . three times!! And STILL the blisters. This time (the painters just finished the porches last week) I've covered the bare wood with three coats (first coat was thinned) of wood epoxy hardener (Abatron) and two coats of SW Duration. I have confidence but my fingers are crossed.
Edited 10/7/2008 3:46 pm by xpayroll
What is the material that you are painting? Wood?
If wood, what kind of wood?
I KNOW WHAT THIS IS!!!
Maybe...
I painted a house in the fall (zone 4 or 5) and had this
exact thing happen.
Well I'm a dummy so I asked the paint guy.
OK I screamed at the paint guy.
He (calmly) explained that it was because it got to cold at night.
Then explained it would go down and disappear (where I hadn't scraped it all to hell) in short order.
No one believed him.
Not me
Not the client
Not my people I dragged over to get there opinion...
But he was right
Sounds crazy but it happened
So...the solution is to keep it warm while it's curing for a few days. Maybe hang a light near the bad spots?
Paint your house a month ago. No he said it actually wasn't a problem. I don't know myself,
but that job is still good seven years later.
If you've got $35 to experiment with try this. Power wash a section containing a couple hundred square feet. Don't worry about it drying, just apply a latex primer (it is a water base and will be absorbed into the wood, damp or dry). Give the primer 24 hours and topcoat. Buy a gallon each of primer and topcoat at walmart and you will have about $35 in it.
I did this to some crappy old 3/8" plywood siding exposed to weather on both sides with old paint peeling and falling off. It was weathered and hardly looked worth saving. Five years later the paint is still solid.
Of course you could use other brands but if it doesn't work you will just be out more money.
Maybe after brushing a section you can run the roller over it!
....or just pretend to be using the roller. :-)
Beer was created so carpenters wouldn't rule the world.
I would roller it all if I could - just doesn't fit on the underside of the claps or the boards that have a brick ledge under them, or next to inside corners, or in the open soffits...