I almost have all the old wallpaper scraped off. What a job.
THE PROBLEM:
In one corner, there was no wallpaper, just paint. And this paint scraped of pretty easily.
Which brings me to the question: How to prep these old plaster walls so the paint I’m about to buy won’t scrap off. How to make sure it will adhere.
THE CURRENT STATE OF THE WALLS:
There is some “shadowing” of the original colors that is still there. The plaster is very smooth, almost like it was polished.
There are also some places where the patching compound is bare on the wall, too.
SOLUTION?:
I wonder if just a good primer would do it, or if I need to sand the smooth plaster.
If primer is the answer, is there a better brand?
lookin’ forward to your responses!
Megan
Replies
This is really just a friendly bump, I'll tell you what I would do, but I'm no expert on painting so take it worth a grain of salt.
First make sure you got all the old paper glue off the walls...
sand them down to give the old plaster some teeth, wash them with tsp, prime and paint.
I agree with CAG. A glassy surface will not adhere well with paint, so sanding is in order. I painted some trim in our house, right over old glossy paint. It is, of course, now peeling. Preparation of the surface is crucial, and the time will pay for itself.
Cheers,
If what you have is just paper over plaster (except in that small area) you're lucky. No lead paint problem. I'd still wear a good (N100) dust mask. Acceptable for occasional exposure to lead dust, and there could be small amounts of asbestos in old plaster -- no safe exposure level there.
And easy on the sanding. It doesn't take much to remove the gypsum and/or lime, leaving a grainy surface from the sand in the plaster.
I'm a big supporter of the TSP wash as well, it'll help deglaze the wall and give you a nice clean painting surface.
Hey, everyone -- Thanks!
I have heard there are special sanders for drywall that have holes that let the dust fall out rather than accumulate in the sandpaper. How does that strike you?
from this website, for example: http://www.colehardware.com/hotline/99/09/sandpapr.htm
"Abrasive screen cloth, for drywall and plaster sanding, is designed to resist clogging with drywall compound and plaster. "
another link to a 3M product:
http://tools.aubuchonhardware.com/sandpaper_and_steel_wool/sandpaper_and_emery_cloth/drywall_sanding_screen-357170.asp
So, yes, a light sanding with a fine grained "paper" sounds good to me! Better than my original idea of priming only.
Although i am guessing I will have to prime, still.
now,
to the real question,
what is "TSP"?
Megan
p.s. I am indeed wearing a mask, but I am not sure of the specs. I will go check. My husband bought it while I was out of town, and I'm pretty sure he was careful to get one that blocks out the nasty particles -- he got it primarily to wear while doing drywall work.
thanks for the heads up on that!
Tri Sodium Phosphate. It comes in a package about the size of an Uncle Ben's Rice and should be in the paint section of any home despot/etc. Use the real thing, not the substitue, I think the brand is Savoram? Use gloves, and probably eye protection . . .
you might be talking about sanding screens? looks more like...well a screen... then paper, the work well on drywall but I have no experience with plaster. I'd also pick up a few sanding sponges for the tight corners etc.
Don't use a sanding screen on plaster. They're meant to cut at the surface -- remove material -- and you don't want to do that with plaster.
And please don't cover it with joint compound. People pay good money to get plaster veneer applied over sheetrock. It looks better and wears better.
Just make sure you have all the wallpaper adhesive off. TSP should help there.
another vote for T.S.P wash,any repairs with plaster look into some stuff called plaster-weld smells like crap but very important and even you might consider a complete skim coat with joint compound/ structolite mix(with mesh tape if needed on big cracks), then skuff it up a bit then two coats of zinsser cover all primer with a lite sand in between 1st and 2nd coat with 220 sand paper .no sanding on final primer coat than start your painting...........regards bear
'
As an experienced plasterer, I can tell you, you are getting a lot of bad advice. You should never sand plaster. You are only maring the hard polished finish. Think of it like a concrete floor that has been polished with a machine. The hard packed smooth surface is dense and strong. Same with plaster. The plaster will soak up primer like a sponge because the water molecules have left. Sam
sam- then what should we do ?? i just recently did the procedure i pointed out and things look good .but ....??? what is in store for me down the road. help us out here, if i'm doing something wrong i need to get it straighten' out. no sanding even with another skim coat?? how about repairs??"expectations are premeditated resentments"
Also, when you go to prime a wall that has had wallpaper on, you may find an oil-based primer works the best. Most paper adhesives are water-based and I found that using a water-based primer reactivates the glue and it will gum up and make a real mess! The oil- based primer will not do this. Even if you think you have all the glue off, there may still be a very thin residue in some spots. Good luck!
Duey
thanks duey for the response i believe cover-all primer is an oil based primer
44209.9 check this and let me know if the procedure is acceptable...... thanks again...bear"expectations are premeditated resentments"
Thanks for the post. I'm a big fan of plaster, but I'm not a plasterer. I shudder when I see it covered with drywall.
I was wondering if you knew of a product, manufactured in Maryland if my memory is working, that you apply over sheetrock to give plaster veneer a surface to adhere to. I've seen it advertised, but I went looking for it with no luck.
Thanks!
It's called Plasterweld and I forget who puts it out. Another one is called Thorobond (sp?). It's a pink gluelike liquid which comes in quarts and gallons. Follow the directions. You should scarify the surface if needs, then paint this stuff on and let it tack up for an hour or so then start your veneer plaster. It's better to do two coats. You can apply the plaster when this stuff is dry because the wet plaster loosens the surface when it goes on just enough to form a bond. I've been using it for 25 years or so.
Plaster-Weld was it! Thanks!
I found the following additional info online --
Larsen Products Corp. 8264 Preston Court :: Jessup, MD 20794 :: 800-633-6668 :: Fax: 301-776-2723 http://www.larsenproducts.com/bonding.htm
Plaster-Weld, bonds new plaster to any clean, structurally sound, interior surface. Weld-Crete, bonds new concrete, stucco, tile setting beds and terrazzo to any structurally sound surface, interior or exterior. Acrylic Admix-101, an integrally added bonding agent to bond new concrete, portland cement plaster, and mortar mixes.
Ruberoid Building Products, Dublin, Ireland Tel: 01 456 4433, Fax: 01 456 4291
THOROSEAL, a cement-based coating for waterproofing concrete and masonry, above and below ground. http://www.ruberoid.ie/ruberoid31.htm
Ironite references I found were generally about a fertilizer called Ironite, but I did find this site, http://www.ironitefloors.com, with links to different Ironite formulae used on/in concrete.
We have stopped using plaster (PVA) bonding agents over everything except cement block and concrete, where it works great. There are many reasons for this. Most plaster resurfacing is over old wood lathe conventional (3 coat) plaster. When using a bonder, the water from the plaster activates the bonder. That is why you only have 10 days to plaster over bonder. After that period the bonder will not activate with the plaster like it should. Anyway, when the plaster goes on, lots of moisture makes its way into the old plaster and into the lathe. Then resins from the wood lath seep out into the plaster and leave stains on the white finish coat. Even when we used a plaster base coat the resins soaked through to the finish coat. Also all that moisture makes the lathe and framing swell up and later dry out which I think caused some degree of map cracking. Additionally, when the surface we are going over has areas with different amount of suction the plaster trowels different over various sections of the wall. For instance, a wall with a piece of blue board covering where a door used to be and an area where some of the wall paper and glue just wouldn't come off, and an area where the finish coat broke away. all on the same wall.
The Solution: We trowel Durabond (hot mud) over the entire surface. The durabond has better adhesion, and does not put much water into the wall beneath and subsequently prevents the water from the plaster to penetrate as well. It creates even suction over the entire surface. We embed fiberglass mesh over the entire surface. It strengthens the wall against cracks and makes it easy to trowel the sticky hot mud. As the mud begins to set we trowel off excess leaving a flatter surface without trowle marks. The hot mud has great tension strength, and the plaster base coat we put on next has great impact strength (3000 psi). The durabond is very crack resistant. We then cover it with our special formulas white coat plaster. (You can use whatever) We can do it all in the same day. With bonding agent you could never put a base and finish coat on it the same day without problems.
If you sand plaster, you might as well have joint compounded it. One other note: Ready mix joint compound is #$*^$%*(*. We refer to it as NO PURPOSE JOINT COMPOUND. The stuff has zero strength and can be reactivated by water. If you ever need to fix something minor over a painted or primed surface use Easy Sand, which like Durabond comes as a powder and sets. If you water trowel it as it sets you can avoid or minimize sanding.
Sam
In addition to what Sam says we have always primed everything with a shellac base primer before we use any bonding agents in case of any seepage. We are using bonding agents less and less these days as well. I think a mechanical bond is always best. Also it's always best to make your base coat the same all the way around instead of top coating over one material then another even if they are flat and even. Different materials suck up moisture at different rates.
Thank you for all of your advice and direction.
As I said, I'm not a plasterer. I've done plenty of drywall, but I prefer plaster for both strength and appearance, and I've often wanted to use plaster, so I've tried to learn a bit about it -- but I'm not ready to do my own plaster & lath walls just yet. I might try a veneer coat, where practical, just to get started. That's why I was asking about bonding agents.
Right now I'm facing just about every "plaster" situation that I can imagine. I'm renovating late Victorian houses that have plaster over brick, plaster over lath, sheetrock over plaster over brick or lath, water damaged & collapsing plaster/lath ceilings, partial renovations (owners gave up) where some or all of the plaster & lath ceilings and walls are down, but the plaster over brick walls are still covered -- with 100 years of paper and (peeling) paint over just about all of the plaster.
Many of these houses were split into apartments during a WWII housing shortage, and each house seems to have been redone differently. The only common thread seems to be loose plaster in plaster/lath ceilings. Or maybe that's just age?
Then there's the odds and ends. Like the "let's see what's behind this wall" spots where the plaster was removed just enough to expose some brick. Or rooms where all of the plaster came down, leaving only four walls of very old brick -- dull. And then there're the living rooms with the ornate decorative plasterwork on the ceilings and upper walls, work that should be preserved if I can get the lead paint off.
It now looks like removing the paper and paint from the plaster using a caustic stripper and a pH-adjusting water wash will leave some very wet plaster that will have to be given time to dry before patching and finishing. Sigh.
I'll check into Durabond. But I'll probably leave the heavy work to a plasterer.