Finally to the painting level of my old house repair. Tonight I was rolling on the finish coat of latex over a coat of latex primer. This is on an old plaster wall that I have been skimming with various drywall compounds (both setting and pre-mixed). In two small spots–one fist-sized, the other quarter-sized–the paint bubbled up. What’s going on? If the wall didn’t like the latex, wouldn’t the primer have peeled? Both paints are Ace’s best. I don’t think this is a reaction from contact with the plaster, as I tested this finish paint directly on some sound plaster–no problem. Well, I haven’t tested TWO coats over pure plaster….. Should I?
I am using latex now because of recommendations to avoid oil paint–it would create a vapor barrior on the inside of my solid masonry wall, and then the wall couldn’t dry to the inside (outside of brick wall is painted). Last year I used oil on the interior walls with good results.
Could this peeling be just an isolated area of grease or something similar? And, on the remainder of the wall that looks good now…..will it continue to look good for the next 20 years, or am I courting continual peeling?
As usual, many thanks. Your tips last week regarding siliconized latex caulk to seal the gap under the chair rail were right on.
Marc
Replies
Can't really tell without being there. Many things can go wrong. Contrary to popular opinion, painting is a trade that requires knowledge and experience. Not to offend you in any way, but I have yet to see a HO who can do a good paint job AND make more than minimum wage doing it (as compared to a good painter).
Your best bet is to have an experienced painter look at it and try to figure out what happened.
By the way, no paint, oil or latex, is a vapor barrier. There are special coatings you can apply as vapor barrier, but those need to be applied very thick and can only be sprayed .
DG/Builder
Marc sometimes in my exp. when your painting on walls that have alot of patching and skim coating is the wall gets to "wet " from the paint / primer and it will actually pull up your drywall compound ,
Best thing to do is to move on to next section wait for it to dry and sand it a down little and repaint good luck !!! DAN K
The peeling spot could certainly be an isolated spot of grease or dust or dirt. It's important to have the walls clean, and the primer relatively fresh (a couple weeks). it's also important that the walls are dry- has the plaster/drywall work been done for a while, and the temperatures inside the house been warm?
If it's just one or two spots, my guess would be a spot of dust or something, just a little more prep work needed next time.
zak
Oil primer is the best product for priming plaster.
Latex is the best product for gyroc and joint compund setting or otherwise.
That being said for a mix of both of these things Oil would be the best bet. It will provide the best bond and foundation for your finish coat which could be latex or oil.
Zak is right that proper preparation is key to successful finish coats. If there is residual wallpaper paste, grease or soap ie. behind a sink it will react with a latex paint. This is another reason why Oil is so fantastic in this situation. If there is some trace amount of these resudues, after proper prep, Oil will not dissolve them and cause problems with adhesion.
As far as an oil being a vapor barrier some are some are not. If you have a problem with your walls breathing this coat of primer will not add to it.
Easy to give advice AFTER the problem
Good luck,
Jon
What a mess--see photo. I thought I would simply scrape off the bad area of paint where it had bubbled, and boom--disaster. As you can see, the paint is peeling off like a sheet of plastic. Here is the autopsy of the wall: this is a section I worked on one year ago. I painted the plaster with an oil primer, then didn't touch it for a year. Last month I skimmed it--over the oil primer--with DW compound to smooth out the irregularities. I used the new Plus 3 "Dust Control" pre-mixed stuff, and maybe Easy Sand. I wonder about that new stuff..... Anyway, before I painted it this week I went over it lightly with a damp sponge to remove the dust. So there is a thin layer of DW compound over the old oil primer, and to this the new latex primer and final paint were applied. Hmmmm, could the latex have softened the compound, as you suggested? It seemed pretty soft as I peeled off the paint, also slightly dusty or chalky.
Ugh....now what? Looks like I have to scrape and sand all the compound off the paint and start over. Then prime and paint with oil paint so be safe???
The little test I told you about where I painted some latex paint on the pristine plaster is holding really tight. Problems probably arise with latex "flooding" compound?? Guess I'm going back to oil.
Your thoughts, and any other ideas to remedy this mess? I was hoping to finish the foom tonight. Maybe this month....dang.....
Marc
This is a typical result of priming a skimmed wall with a latex primer. See, latex primer is great for GWB becuase it soaks into the paper of the boards. However, latex primer literally floats on compound or plaster. It has minimal bonding ability to such a surface.USG will tell you the same thing. So will Benjamin Moore. If you did a VERY light skim over GWB you may have gotten lucky if the latex primer was able to get in contact with the paper face.Alkyd (oil) primer actually soaks into the compound or plaster. That is what creates the bond strength. Peel off as much of the latex primer as you can. Doing it sooner rather than later will serve you best. The primer will not have sured and will come off in rubbery sheets. After it cures and become brittle, it will come off in chips and you will damage more of the walls by the add'l scraping required. Leave alone whatever actually did bond to the compound. If it ain't broke, don't fix it.After scraping, repair any gouges with compound, readymix or setting type, sand and reprime with an alkyd (oil) primer. Then you can paint using a latex finish paint.FrankieThere he goes—one of God's own prototypes—a high powered mutant of some kind never even considered for mass production. Too weird to live and too rare to die.—Hunter S. Thompson
from Fear And Loathing In Las Vegas
Edited 4/14/2006 4:14 pm ET by Frankie
Thanks Frankie, as a remodeler for umpty-ump years I've had umpty-ump problems along these lines and your post is the first to make sense. Thanks.
Is there a chalky residue on the wall. It looks as though there may be an old water stain of sorts. Perhaps there is some sort of residue on the surface ( efflorescence? ). Personally, I would worry more about the outlet than the paint. Old houses are supposed to have peeling paint, tell others you are doing a historically accurate repair.
How damp was the sponge that you used to clean the compound dust off the wall? Usually, I will dust the wall with my hand or a dry rag, but if I really need to keep airborne dust to an absolute minimum, I will use a rag that is squeezed as dry as I can get it.
If enough moisture gets on the the compound, it will leave a thin layer of compound that is not properly adhered. Another way of looking at it is: adding water to compound dust will not re-create compound. Could this be what you're experiencing? If the 1st coat caused little bubbles on the wall (even if they went away after drying), then that may be what's happening.
-Don