How to paint over damp wall?

[geraldthehamster]

So I can not use Johnstone's One Coat Matt Emulsion - Brilliant White or Thompsons Damp Seal ontop of PVA?

Is there anything I can use ontop of PVA or just leave the PVA on by itself? with no undercoat or overcoat?

PVA was only mentioned because someone suggested skimming the wall.

PVA - is used on a wall before skimming as it helps the plaster to adhere.

PVA - should never be used on a wall before painting as it will prevent the paint from adhering well.

Simple as.

Cheers
Richard

 

[blackcloud]

Thanks, what does skimming the wall mean? I have taken off all the paint from the wall and just have the bear plasterboard now.

So if PVA can not be used on a wall before painting then do you mean I should just apply the PVA and nothing else?

 

[blackcloud]

I called Layland and they said not to use PVA but to use
Truguard Stabilising Damp Treatment and the apply Emulsion ontop of that and thats all I need to do.
What do you think?

 

[geraldthehamster]

Thanks, what does skimming the wall mean? I have taken off all the paint from the wall and just have the bear plasterboard now.

So if PVA can not be used on a wall before painting then do you mean I should just apply the PVA and nothing else?

Skimming - applying a thin finishing layer of plaster or easifill.
Unless you're going to do that, or have it done, there is no role for PVA here.

 

[misterhelpful]

That Leyland Truguard damp stabiliser is a new product to me - most stabilisers are used on exterior surfaces but, having had a quick look on their website, it does seem suitable. I see no reason why it wouldn't work for you in this case, so give it a go, if you are happy to.

The PVA debate is a long and old one, but the stuff always ends up causing problems, which is why I think manufacturers now inform you not to use it with paints. Basically, it waterproofs the surface which stops paint adhering to it, then, as the paint dries it either separates and crazes or simply dries on the surface and ends up peeling off somewhere down the road.

 

[blackcloud]

Do you know of anyother products I could use instead of
Truguard Stabilising Damp Treatment

http://www.leylandtrade.com/products/product-detail/truguard-stabilising-damp-treatment.aspx

As I can not get hold of that product, does anyone know of anyother products that do a similar thing, that will treat the efflorescence before I put over emulsion?

Another option I have been told is this

Arcasaltpetre

http://www.arcane-industries.co.uk/p246_r2475-treat-walls-deteriorated-by-saltpetre-and-dampness-repair-restore-and-protect-plaster-cement-concrete-natural-stone-brick.html

and then once this is applied to use this

ArcaDamp

http://www.arcane-industries.co.uk/p246_r2479-damp-proof-paint-eliminates-damp-in-bathrooms-and-basements-cures-and-prevents-dampness.html

But I have never heard of this company or make? Has anyone else? They ask for your date of birth when you register, which I dont know why?

 

[amfisted]

Actually, reading the thread again, then I don't think my mention of PVA was such an awful bloomer after all. I accept that its not good practice to apply water based paint direct to a surface which has been treated with PVA, but that wasn't actually what I was suggesting.

My point was that if the OP didn't manage to achieve a decent finish on the existing surface to which paint could be applied direct, then a skim layer could be considered; and that would mean preparing the bare surface for the skim with PVA.

 

[misterhelpful]

Actually, reading the thread again, then I don't think my mention of PVA was such an awful bloomer after all. I accept that its not good practice to apply water based paint direct to a surface which has been treated with PVA, but that wasn't actually what I was suggesting.

My point was that if the OP didn't manage to achieve a decent finish on the existing surface to which paint could be applied direct, then a skim layer could be considered; and that would mean preparing the bare surface for the skim with PVA.

Yes, I agree that your mentioning of PVA wasn't what concerned me because, as you state, using if before skimming is fine. I was more concerned that blackcloud sounded like they were going to use PVA to seal the surface before painting, which is why I made my comment. On reading it back, it did sound a little aggressive, but wasn't meant that way.

 

[amfisted]

Actually, reading the thread again, then I don't think my mention of PVA was such an awful bloomer after all. I accept that its not good practice to apply water based paint direct to a surface which has been treated with PVA, but that wasn't actually what I was suggesting.

My point was that if the OP didn't manage to achieve a decent finish on the existing surface to which paint could be applied direct, then a skim layer could be considered; and that would mean preparing the bare surface for the skim with PVA.

Yes, I agree that your mentioning of PVA wasn't what concerned me because, as you state, using if before skimming is fine. I was more concerned that blackcloud sounded like they were going to use PVA to seal the surface before painting, which is why I made my comment. On reading it back, it did sound a little aggressive, but wasn't meant that way.

No problem, and thanks for that.
Such was the vehemence of the response to my mention of PVA (and not only from yourself) that I even managed to misinterpret my own post until I went back and re-read it!

 

[blackcloud]

How can I avoid seeing the old edges of the old paint when I paint the wall?

 

[misterhelpful]

I would mist coat the bare plaster first, as this will show up all blemishes that need to be filled. It will also seal the wall and stop moisture being sucked out of the filler you will need to use.
Once the mist coat is totally dry, use a flexible filling knife or scraper and thinly spread some fine surface filler over the paint edges, smoothing it out as much as possible as you do so. Once the filler is dry, sand away any high spots until you have a nice even surface to paint on. When you have achieved this, mist coat the filler to give you an evenly sealed wall to apply your finishing paint to. Some people will try to sand the paint edges flush but, in the majority of cases, you still end up seeing a slight ridge, which is why I prefer the filling method.
It sounds like a lot more work than it is but I would think you could get the misting done in the morning, go do some shopping or watch the tellybox, fill in the afternoon, have a cuppa and a Kit Kat while the filler dries, then sand off and mist the filler. Start painting the walls the next morning and by mid afternoon you should be all done and cleaned up.

 

[blackcloud]

Thanks, what I was going to do was use Polyfilla Easy Sand Interior Filler 2kg around the edges then use a metal scraper to level it off , then use a sander around the edges to level the edges with the plasterboard and then paint. Would that work do you think.

 

[misterhelpful]

That should be fine. I always liked Polycell Trade fillers and would regularly recommend them. (Can't get them over here, so don't do so now in case they have changed their products.) Powdered fillers are easy to sand than ready mixed as well, so I think that's a good choice - just don't mix up too much at once because, once it hardens, it'll be useless.

 

[blackcloud]

Thanks, I didnt know I had to mix the Polyfilla Easy Sand Interior Filler 2kg with anything? Do you just use water? It hasnt arrived yet as have bought it online.

In your opinion what colour do my walls look.

 

[vinn]

At first i thought you had a condensation issue but It looks like you have penetrating damp. If thats the case then none of the above remedies will work until you first find the cause and second hack off the affected plaster and then use a render to "plaster" the affected part.
Transferring your post to the Building forum will get you more opinions.