Flaking paint

[Jackthebiscuit]

One wall of a large bathroom wont let emulsion paint adhere to it,, but the other walls will.

Its a strange one, but after a few days/week, thin lines appear on the paint and continue to spread over most of the wall like a cobweb, and gradually the lines get wider and the paint starts to peel off. I can only think that there is something within the plaster that reacts to the paint..?

I've tried sizing the wall but it makes no difference. It is an internal wall and the peeling always starts at about eye level, and then spreads to the ceiling and then works its way down to within about 600mm from the floor, and then it stops. It is a large, well ventilated room. So any ideas what the problem is,, and how to cure it.?

Thanks in advance

 

[TheDec]

What you describe is known as crazing, and there are a number of reasons why this can occur, and what your paint system is telling you is it is very unhappy with regard to what is underneath it. You mention sizing, so what did you use to size the wall with and have you painted over it.

Dec

 

[dcdec]

Yeah i'm wondering about the sizing thing as well, its normally a term applied to glue/paste prior to papering.

Is it an outside wall? could be too cold for the paint, but it does sound as Dec has picked up on that there is some kind of contaminant on the surface, what 's on the wall at the moment?

 

[Jackthebiscuit]

Morning and thanks Dec and dec,

For sizing I used wallpaper paste, coated it on twice and let it dry between coats. However, I do recall it took an age to dry, and had to wait until the following day before applying paint. The other walls were not sized, as the paint went on OK. So I only sized the wall when the problem arose. The paint is Dulux emulsion.

It's an inside wall, brick/plaster construction, and 'the crazing' always starts at eye level, and never progresses lower that say 500mm? from the floor, and spreads across most of the width of the wall, but stops about 200mm from the edges. Also as mentioned, the room is well ventilated, so I would eliminate damp, rising or otherwise.

Also, this wall was painted during the summer, so temperature during application also not an issue either.

I agree about the contamination notion, but what contamination could occur to just this area is a bit of a mystery.? If the source of the contamination was known, then there is perhaps a neutralisation product available, but until the cause is confirmed, the remedy is hard to find.

If I were sure an oil based paint would stick, then I would recommend this to the owner, as it would be a simpler remedy than re-plastering.

Thanx again guys for your comments.

 

[Jackthebiscuit]

Just re-reading my post, and a spark appeared in my wee brain.!?

The sizing was a water based solution, and took an age to dry,, so no absorption into the plaster..!?

I know that a damp proof course was installed 'some time ago'. The owner lives overseas and is a bit vague, other than he had problems with the finishing standard of a plasterer, and he was eventually replaced.

So,,, when applying the render after injecting a damp course, a chemical is added to the mix to make it damp-roof. So my 'theory' is that if some of this chemical got into the mix of the finishing plaster, then it would repel any water based solution that is applied to it..?

Do you think I'm 'getting warm' with a reason for it happening.?

Cheers again.

Jack

 

[dcdec]

Nope your freezing cold, very simple answer to this one.... you used wall paper paste as a sealer for the walls!!!

I hope to dear God your not getting paid for this job as a decorator or tradesman because thats about as cowboy as you can get, if not and your trying to help a mate or something i apologise.
You are in a bit of trouble now the remedy is elbow grease, TheDec will fill you in as i cant remember his method.

 

[TheDec]

Well you really have created a monster for yourself, three options, either burn the lot off, sand, or line the walls. If you choose the sanding route using 120 grit sand over the crazed areas and apply a thinned oil based undercoat to the entire wall, face fill any areas that need it and when dry sand smooth and dust off, then apply a thinned emulsion to the filled areas, before you apply your finish coats. This should get you out of the dollie drums.

Dec

 

[handyman77]

Morning and thanks Dec and dec,

For sizing I used wallpaper paste,

You have got to be kidding me. R u gonna tell the client the truth.... Or r u gonna say how you have found a way to save his wall u genius u. You take the biscuit jack.

 

[opps]

soak the paint- the moisture will reactivate the glue and then use a scraper to remove as much as possible. Then sand as much as possble and use an enzyme based paste remover and resand.

Only use a paste size under paper...

 

[TheDec]

It is possible to save the situation here if you first stop the paste being reactivated by further coats of emulsion.

Dec

 

[opps]

It is possible to save the situation here if you first stop the paste being reactivated by further coats of emulsion.

Dec

Zinsser BIN would help to do that.

 

[TheDec]

Yes indeed it would, or any suitable sealer capable of stopping the re activation of the paste.

Dec

 

[opps]

Yes indeed it would, or any suitable sealer capable of stopping the re activation of the paste.

Dec

True

i recommended BIN rather than oilbased paints because of the solvent free clean up and speed of drying