Painting after stripping wallpaper

[Blowfish]

Hi all

I am new to this DIY stuff so please be gentle. I have had a look through this site but have not come up with an answer to my question. Which is :-

I have just stripped the walls (vinyl wallpaper) of our bedroom, taking the top layer off then taking the backing paper off. All went well but on a lot of areas the backing paper also brought off the paint on the plaster (plaster board skimmed, I think, House 10 years old) there is no damage to the plaster. Now I realise I have remove the loose paint and reseal the exposed plaster, but how do I prevent the patches coming through when I paint? Do I just use undercoat, or filling and sanding or am I looking at lining paper (which I don’t want to do) some of the areas are quite large; the plaster is in very good condition. I could just leave it until all the paint peels off, but I think my wife would leave me!

 

[Zampa]

The paint was probably th original contract emulsion and because of the stripping process, has lifted and blown...the rest will hopefully be ok.

Give the whole wall a coat of thin vinyl matt emulsion...fill around the edges where to paint had blown..sand down then paint the whole wall as normal

Only concern here is the fact that you may have two different surfaces left...the if you count the filler thats been sanded....the plaster will be smoth-ish...then youl have the filler which will be flat...then the original paint....which will have an orange peel stipplr effect.

If this does shown up then you will need to line the wall in order to ge a uniform finish.

You could always take the rest of the paint off...you may be able to wash it off...then mist coat the wall and then give it two full coats.

 

[Blowfish]

The paint is begining to peel/flake from where it was removed by the backing paper. By wash off do you use water? a solution of some kind? If I just do the painting method should I mist coat the exposed plaster with a non vinyl paint?

 

[Zampa]

The paint is begining to peel/flake from where it was removed by the backing paper. By wash off do you use water? a solution of some kind? If I just do the painting method should I mist coat the exposed plaster with a non vinyl paint?

By wash off do you use water?....yep warm water and detergent...this will only work though if the paint is contract emulsion..you can easily tell...wet it and see if the colour start to come off

If I just do the painting method should I mist coat the exposed plaster with a non vinyl paint?

...nope it doesnt have to be non vinyl (contract) emulsion...thats only really needed when the plaster is fairly thick on new work and the walls need the breath.

Sounds to me like your problem has been caused by the original painter lobbing the emulsion on like its going out of fashion so it covers in one or two thick coats.

Sadly its not always the painters fault...they are given rubbish prices by their boss'es who in turn have had their price forced down by the main contractor

As an example round this way the contractor gets about 1,300 quid inc materials for a three/four bedroomed house...the painter will get about 500/600 quid out of that to do it.....so, in order for him to make a half decent wage, corners have to be cut, big corners.

 

[Blowfish]

thanks for the info, now i just have to wait for the enthusiasm to kick in.

 

[Zampa]

Hvae a go...make a right mess of it...wife will get the hump and do it herself...problem solved!

 

[Nestor_Kelebay]

Not sure if you have plaster walls or plasterboard (which we call "drywall") walls, since you refer to both. On a 10 year old house, I presume it's plasterBOARD.

#1:
If the paint is missing, in my view, you can simply apply a PVA primer directly to the bare plasterboard or, apply joint compound over any joints or drywall screws, sand smooth and primer with a general purpose PVA primer.

(Remember, PVA primers and paints soften up and loose their adhesion when they get wet, and that's probably why the PVA "contractor emulsion" that you probably had on your walls is now peeling off. Until now, as long as the wall was dry, it stuck well. If it had been peeling before, then your wallpaper would have been peeling off as the PVA paint it was stuck to was itself peeling off the plasterboard. And that wasn't the case, right?)

#2:
If the smooth white surface paper of the plasterboard has been pulled off, exposing the rough brown paper below it, then I would:

a) dilute some white wood glue with enough water to make it into a paintable consistancy and paint that onto the brown paper. The solution will soak in, and as it dries it will glue all the paper fibers together.

b) Now, spread a skim coat of drywall joint compound over that dried brown paper patches, allow to dry, sand smooth, prime and paint.

#3:
If the paper over the gypsum core of the plasterboard has been pulled off, exposing the bare gypsum, you can still fix that if the gypsum core is still solid and in one piece:

a) Stick strips of self adhesive fiberglass mesh drywall joint tape over the exposed gypsum core. Run the strips of tape parallel to each other and have them go completely across the exposed gypsum and a few inches onto the paper on each side of the exposed gyspum.

b) Paint over those strips of fiberglass mesh with white wood glue diluted with enough water to make it into a paintable consistancy. As the dilute adhesive dries, it will bond the fiberglass mesh to the gypsum core and the paper on both sides.

c) When the adhesive is dry, apply a second coat of fiberglass mesh tape strips running perpendicular to the first coat, and paint over that second coat of tape with dilute adhesive too. That will bond the second coat of fiberglass mesh to the first coat, and now the fiberglass mesh is essentially taking the place of the missing paper.

d) For added security, apply another two coats of fiberglass mesh on top of the first two. Otherwise, skim coat with drywall joint compound, sand smooth, prime and paint.

Also, whenever applying any sort of plaster (including drywall joint compound) or sanding it smooth, work with a bright light shining at a sharp angle to the part of the wall you're working on. The shallow lighting angle will exagerate the roughness of your work, giving you a much better mental image of where you need to add plaster and where you need to sand it off to get a smooth surface. When your work looks acceptable to you under such critical lighting, it'll look professionally done under normal lighting.

 

[Blowfish]

Well over here, UK (and anyone with more knowledge may correct me) we use plasterboards for the walls then they are skimmed with a thin layer of plaster to give a smooth finish ready to decorate. And as Zampa states the undercoat was probably slapped on, and then wallpaper put on top of it. On removing the wallpaper some of the undercoat has come off reviling the skimmed plaster which is in very good nick. I have heard about using PVA is it in the same PVA you refer to that we use over here as a lot of people here and on other sites would strongly disagree with using PVA. Thanks for your input, if anyone else wishes to join in then please feel free. It gives me an excuse not to get started.

And Zampa my wife did my daughters room which went the same way, but she carried on regardless which is why most of her paint peeled off, and why I am doing our bedroom.

 

[Nestor_Kelebay]

1. If it's only the undercoat that's come off, can you not simply use a primer over top of the bare plaster skim coat to prep for painting?

2. If "a lot of people here and on other sites would strongly disagree with using PVA", what reasons would they give for telling you NOT to use PVA?

That is, if you use diluted white wood glue to stick skim coat plaster to plasterboard, and neither the plaster skim coat nor the plasterboard are waterproof, what reasons would they give for telling you not to use an adhesive that isn't waterproof? If the wall gets wet, the plaster skim coat and probably the plasterboard are gonna fall apart along with the PVA glue, so wherein lies the advantage of using a waterproof glue to hold them together?

When I say PVA, I mean polyvinyl acetate in the form of either:

a) white wood glue, or

b) a general purpose primer or inexpensive emulsion paint.

Both of the above will be made from tiny particles of polyvinyl acetate plastic. I trust that is what is meant by the initials "PVA".

You can use a concrete bonding agent to glue the plaster skim coat to the plasterboard. It will cure to a film that is unaffected by moisture. But, if the two things it's gluing together will disintegrate if they get wet and have to be replaced anyway, where is the advantage of using a waterproof adhesive to hold them together?

Either I'm misunderstanding something or we're not talking about the same thing here. It just doesn't make sense to me for someone to say to use a waterproof adhesive to glue non-waterproof stuff to non-waterproof stuff unless the reason of that advice has nothing to do with moisture resistance.

3. I'd like to talk to whomever would tell you not to use a PVA adhesive on a wall to find out what the logic they're using is. Do you follow my reasoning?

 

[Nestor_Kelebay]

Why take my word for it? Why not prove it to yourself? Why not use some white wood glue to glue two pieces of scrap plasterboard together. Then use Chinese water torture on that assembly to see if the glue dissolves before the plasterboard is so badly damaged it would need to be replaced anyhow. (Be sure to allow the glue to dry fully, tho.) That will be the true test of the pudding.


PS:

I've been using white wood glue diluted with water to both help finishing plaster stick to walls and ceilings and mixing base coat plasters and finishing plaster powders with diluted white wood glue to make them both stick better and dry harder for over 15 years now, prolly closer to 20. That is common practice on this side of the pond.

And, the walls and ceilings I've used it on have been in bathrooms too.

I'm guessing that if there was a problem with using PVA glue in a wall or ceiling, even in the wall or ceiling of a bathroom where there is a higher humidity than other rooms, I probably would have found out what that problem is by now. So far, no problem.

You see, PVA glue doesn't fall to pieces immediately upon it's learning that there's a remote possibility of water being nearby. Otherwise all of the high quality wood furniture that's glued together with PVA based wood glues would all fall apart the first time you spilled some water on them or cleaned them with a damp cloth to pick up the dust.

PVA based wood glues will re-dissolve (kinda) in water, but they gotta get real wet for quite some time for the glue to come apart, and moisture sufficient to dissolve that PVA glue is gonna also cause significant water damage to the plaster and plasterboard too.

If someone can see where my thinking is wrong on this, can they please explain it to me?

 

[Blowfish]

Hi again I see that you have put your points forward on PVR (yes we are talking the same) at other threads in this forum, and if you search this forum for PVR you will get different views. Plus if you have a look at these links below they are not pro PVR.

http://www.screwfix.com/talk/thread.jspa?threadID=29496&tstart=0

http://www.screwfix.com/talk/thread.jspa?forumID=26&threadID=29496&messageID=286882#286882

Now I am not questioning your experience, but obviously when you get so many conflicting views it does leave to some confusion, I also read somewhere (cant find it now) about the walls having to breathe or am I just confusing the issue. Also as I mentioned at the beginning of this thread “I am new to this DIY stuff so please be gentle”. I also noticed Zampa had a view on this in other threads. Thanks for your help now I wonder how long I can string this job out.

 

[Nestor_Kelebay]

You see, one of the problems of DIY work in general is that it's not "taught" anywhere like plumbing, wiring, carpentry and the other recognized trades are. So, as a result, people turn to the more knowledgeable or experienced people for advice and explanations, and often those people don't really know themselves what the answers to those questions are. Also, new products are continuously coming out, and despite the claims they make have trouble gaining acceptance because any product that claims to offer better results than what's currently being used will be viewed with scepticism. And, finally, the products we DIY'ers are using are, in many cases, recently developed chemicals and plastics that only the chemists working for the companies that produced them know and understand their properties. None of us are chemists and we can only learn from our own experience whether they live up to the claims made by the manufacturers and are appropriate to use in our circumstances.

My advice is this:

Don't take anyone's word for it, do your own experiment. Glue two scrap pieces of plasterboard together and allow the glue to dry, and then get that assembly wet to see if you're satisfied that the PVA glue is water resistant enough that it won't be such a weak link in the chain that using it will create problems where none would otherwise be created.

I use white wood glue all the time in my plastering work, and the ONLY time I've ever had a problem is when I've tried to paint directly over a film of dried white wood glue with a water based primer or paint. If the wood glue is under a layer of plaster or dispersed in the plaster (as if you mix the plaster powder into diluted white wood glue), I've had no problems even on bathroom walls. However, perhaps it's the fact that I use a paint specifically meant for bathrooms on my bathroom walls that's helped out, I can't say.

Lemme tell you three things:

1. If you're concerned that the use of PVA in plaster work will lead to problems, go buy a gallon of "concrete bonding agent" instead. This will be an adhesive just like PVA, but will cure to a film that will be unaffected by moisture. It's not expensive and it'll give you all the adhesive properties but will still be completely waterproof when fully cured, and it's already mixed to a paintable consistancy.

2. In all things, do your own testing to see if you are comfortable with the materials you're using. Glue two pieces of scrap plasterboard together with white wood glue and see if the glue is less water resistant than you were expecting.

3. NO ONE, and I mean NO ONE, comes on these boards and uses their own valuable time to deliberately spread wrong or bad advice. EVERYONE I've ever met who answers questions on DIY forums does so with the very best of intentions. The reason why there are conflicting posts is because people have different experiences under different circumstances. However, at the end of the day, the bottom line is that disagreement amongst the experts on these forums is ultimately beneficial to everyone. Unfortunately, an argument between knowledgeable people in a DIY forum is the ONLY way that the newbies in the forum can learn enough about the various aspects of a technical issue to walk away from that discussion with enough knowledge to form their own educated opinions, and that's the ultimate objective of every newbie facing a problem he doesn't really understand. That objective, however, is best met when the knowledgeable people restrict the discussion to the technical issue, and not let it degrade into a name calling contest. I'm old enough to have learned that there are lots of people that know more than me. Hopefully, we're all that way.

 

[bludger]

Hello Nestor,

Just caught up with this thread. Just want to say that your last post is admirable and something we can all learn from.

Best wishes,