getting paint to adhere to plaster

h82diet

Hello!
I have this closet and I cannot get the good quality flat paint to adhear to the plaster on the inside. Someone told me about 25 years ago that I have to treat the lime in the plaster to get adhesion and I've forgotten what he said. Any suggestions? The paint just peels right off... but not everywhere. The plaster is smooth, not chalky.

ric knows paint

Over time, plaster becomes extremely hard and slick...and, as you've already experienced, so slick it's difficult to get paint to adhere properly. The fact that plaster is naturally highly alkaline doesn't help much either. Proper and complete surface prep becomes the most critical factor in painting this surface successfully.

Remove as much of the existing paint as possible (most of it will come off easily) and, assuming it's clean, etch the plaster by scrubbing with a 50/50 mixture of white vinegar and water - this helps to microscopically "profile" the slick surface for better adhesion, plus neutralizes the surface alkalinity (for best results, spray surface with vinegar solution using a spray bottle or pump-up garden sprayer - then scrub. Dipping a sponge into solution then scrubbing wall - then dipping sponge again will only neutralize your solution and render it ineffective). Rinse with clean water and allow to dry. At this point, there are several schools of thought on the best way to prime and paint aged plaster - for years, alkyd/oil primers were the industry's best offerings, but new technologies have elevated acrylics to a much better, longer lasting foundation coating (Bulls-Eye 123 et al)...My personal favorite, for slick, aged plaster, however, is pigmented shellac (BIN - available at any independently owned paint store, big box, company store, hardware, etc.). If you've never used it before, the fumes will have you bumping your head on the ceiling without proper ventilation (relatively harmless, but strong), but the product is naturally alkali resistant and the adhesion is phenomenal. If you decide to use BIN (I mention that particular brand name 'cause they're pretty much the only manufacturer of pigmented shellac in the country), the fumes will dissipate quickly, can be top-coated in about 45 minutes with any type finish (stay with a latex type coating though), and your problem should be solved. Best of luck and let us know how it turns out.

h82diet

Dear Ric,
Thank you very much for your thoughtful reply. I am very familiar with BIN because years ago I bought a house and painted the entire inside only to have horrid brown spots that dripped down the wall appear the very next day. (the prior owners were chain smokers). We then had to prime the entire inside with BIN and then repaint. Within one year the paint fell off the ceilings and the Ben Moore guy came and said that the BIN had failed to adhere to the paint that was on the plaster... because what peeled off had left the plaster exposed. I still like BIN (though I wish it didn't have such a sheen when dry) and will do everything you recommend before I repaint my bare plaster first with BIN then the paint. You're right, the plaster is hard as a rock and shiny.
Thanks again!

chrisn

relative to what?
mustard gas?

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ric knows paint

Sorry to hear about your last paint adventure - that had to be a mess...Just for the record though, it sounds like the BIN adhered to the surface it was applied to (the previous coat of paint) - the surface it was applied to didn't adhere to the host (the plaster). Unfortunately, the industry really doesn't offer a conventional primer capable of binding a poorly adhering coating to a substrate. Best wishes for your new project.

chrisn

I still believe that the statement " ric knows paint" made needs to be addressed,
Mr Ric might very well know paint but to make a comment like Bin fumes are "relatively harmless" is way misleading, at best.

http://www.essortment.com/can-paint-...age-60694.html

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ric knows paint

You're right, Chris...it would be misleading to suggest that denatured alcohol fumes are even close to being a "safe" solvent to ingest - kinda stupid and irresponsible, actually. In my mind I'm thinking I'd rather be applying BIN in a closet and dealing with those fumes, versus the solvents (and their respective fumes) found in some of the quick dry alkyds...I probably should limit my comments to the composition and workings of paint as opposed to the toxicity and exposure of elements I really don't know much about.

jsheridan

I think that the solution is to not, unless directly asked, give advice on the issue of toxicity of fumes of a legal product, for a number of reasons. Before someone suggests that I want to encourage people to huff paint/solvent fumes, let me say, I don't. That's the immature way some are, if you're not totally, vehemently against what they're against, you're totally in favor of the opposite. I assume that everyone I encounter here is a thinking, rational, responsible, mature adult and, as such, can make their own determination as to what constitutes a danger to their health. Every paint can is chock full of warnings, to an overblown extent, about breathing, drinking, skin/eye contact, sanding dust, lead exposure, etc, etc, etc. Enough. I read most all can labels of products I use, and the room required to post all warnings takes valuable real estate that could be better spent advising me how to use the product, its specs, and what I can expect it to do. And at that, you need a magnifying glass. Let's save the multiple languages for another thread. Reading the label is being responsible, which if you don't do, you get what you get. The body is equipped with sensors to alert you that something is disturbing or injurious to you, use them, don't wait for me to tell you. What is so is different for all. If something disturbs you, don't use it or better equip yourself. Isn't protecting yourself against nasty chemical smells intuitive? I don't assume people are too stupid or that physiologically ill equipped. That's the basis. We only know these chemicals are dangerous(?) because someone has told us, and in California, everything is considered a danger, except those giving the warnings. I've been breathing paint fumes/solvents, dust, lead, silica, fiberglass, asbestos, etc., day in day out, for the better part of twenty five years or so. I'm not dead, as suggested by the blinking cursor I can see. And, I've been a smoker for that duration as well. And I know plenty of old, seasoned painters, who are very much alive, some to my chagrin. With that comparative, aggregate experience, it's almost ridiulous to think that the incidental exposure that a homeowner will experience will be a deadly encounter, or create serious long term health consequences. The may be some, like asthmatics or those pregnant, who may have adverse consequences, but don't they already know their natural defenses are compromised and should take added precaution or abstain? Take smoking, how could anyone in their right mind believe, or claim to be lulled into believing, that breathing smoke from burning substances into their lungs isn't/couldn't be harmful? There's a drive here in Cape May to make the beaches and other public areas smoke free. Okay. There are those who are resistant to creating smoking sections at the entrance areas on the chance that a child will walk by and be exposed to second hand smoke. Really? If second hand, or first hand for that matter, were that dangerous/deadly, I wouldn't be seeing the blinking cursor. Again, for the immature, I'm not promoting or condoning smoking. I simply use it to illustrate the ignorance and hysteria that surrounds the use of chemicals and the incidental exposure to them. We're not talking radiation here. I'm not against advising/warning people. If I saw a hole in the ground, I would warn you. If you're contemplating using volatile solvents in the presence of pilots, I'll warn you. When it comes to what is noxious to you, I'll leave your sensors to warn you of that. With the latter, your senses are there to warn you before the injury. With the former, it's the broken leg or the explosion that wakes you up. Just my opinion. Thanks for the rant.
Joe

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Brushjockey

Nice paragraph joe!! And so big! lol

I do think the great adhesion acrylic primers will do the job- they have for me MANY times.

Very seldom do I run into virgin plaster though. This isn't either. Fully cured.
The wash that ric said is great idea- then a good primer - doesn't need to be BIn or oil- Z 123, BM fresh Start, Z's Smart Prime, etc. Not a difficult problem.
The problem i do usually see is someone hits raw plaster with a flat latex. That will eventually fail.

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joecaption

I just prime with an oil based primer and it not only sticks but stops and brown looking stains from coming through like when you use a latex primer.
Once the oil primers dry it can be painted with latex paint.

jsheridan

Thanks Brush, I know. I didn't know I had it in me to be that wordy!
As to the thread, when it comes to priming plaster, I still like my tried and true Cover Stain oil. I agree with joecaption, who, by the way, I welcome to the forum.

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Brushjockey

I know you do. I think there's a 12 step program for that... lol

Bleeding is a different issue- and not caused by plaster.
But you oil guys just keep on...

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ric knows paint

Regarding the thread, I agree with everybody (how's that for sounding sufficiently wishy-washy?). Cover Stain is a great product and is listed as a "VT Alkyd" coating - The problem with alkyds are their sensitivity to alkaline substrates. They will obviously adhere well to a plaster surface but, if moisture is present, saponification is always a possibility. Personally, I believe Cover Stain is NOT a simple VT Alkyd. Zinsser is very protective of their formulations and VT Alkyds (primers or finishes) are typically not recommended (a) for exterior applications (poor gloss retention and UV resistance) (b) as wood primers, especially whole house primers (too brittle) or (c) for use over slick, glossy surfaces without sanding (alkyds need penetration) - and Cover Stain is recommended in all these instances...I could be dead wrong, but I believe Cover Stain is an Acrylic modified VT Alkyd (which makes all sorts of sense in my tiny mind)...

Acrylic Bonding Primers will work great also, they have outstanding adhesion and are alkali resistant, but take a while to cure. During that critical 10-15 day cure time, the outstanding adhesion of these products just ain't there. That's not to say a problem will occur, it's just something to be aware of.

...and therein lies the reason I prefer pigmented shellac, the curing. Since shellac cures solely by solvent evaporation, it's the only product (of the 3 mentioned) that reaches it's max adhesion within an hour or so. Since the product is alkali resistant and cures so quickly, you don't have the worry of an acrylic coating "lifting" a partially cured primer from the surface during it's cure cycle.

Each of these primers could, and will, work on plaster when applied properly. In my opinion, I believe shellac is the safest bet on the long term success of a paint system - and, of course, by "safe" I mean a "safe" recommendation for use as a primer...

jsheridan

VT Alkyd?

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ric knows paint

Vinyl Toluene Alkyd (often short-oil),...typically used in fast dry products, shop coat primers, quick dry alkyd stain blockers, etc. Not typically used in higher quality finishes as they really don't penetrate a surface very well, are not known of their UV resistance (fades and chalks quickly), and dry so brittle (similar to lacquer) that, over time and with any surface movement, lose adhesion - especially on slick, smooth surfaces since penetration is limited due to the quick dry time.