Paint Problem

[Nodge]

I have a strange problem with some emulsion painted walls. Must be 6 or 7 years ago since I decorated the hall & landing. I put up a dado rail and painted above the rail a light green and below a slightly darker green. I'm pretty sure that I sealed the walls first with some dilute pva. About a year ago we first noticed some rough patches appearing in the light green upstairs on the landing. Since then it's just got progressively worse. But it's only the light green above the dado rail and it's only upstairs on the landing. Everything is fine down in the hall, and the darker green below the dado rail is ok up on the landing. The rough areas are where the paint is flaking off. Not in big blisters - just very small rough bits.

I've never come across this before and I don't know what's causing it. I don't think it was my preparation as the paint everywhere else is fine. But if it's the paint, why isn't it happening all over - not just upstairs? The walls are all internal walls so it's not damp from the outside or anything. The problem is what to do about it. If I just sand the bits that are flaking and repaint I'm worried that the old paint is just going to carry on flaking. I get the feeling that I need to get all the old emulsion off the walls and start with bare walls again.. Would this be the best thing to do and how would I go about it?

TIA John

[Harry Bloomfield]

Nodge presented the following explanation :

Often it is caused by some damp, it doesn't need much to make it flake. Is it near a widow and perhaps there is some leakage or tracking via the frame through to the brickwork?

[mr fuxit]

The rough areas are where the paint is flaking off.

It's almost certainly caused by sealing the walls with PVA. New plaster should be sealed with diluted emulsion paint.

[Phil L]

Considering it's been on for 7 years, it's not doing too bad.

Without seeing it, I'd say it's peeling due to shrinkage - even though your house looks stable and the walls solid, they are in a constant state of flux, moving slightly with hot and cold cycles, and also humid and dry periods all take their toll, what started out as minor imperfections, invisible to the naked eye, have now given way to flaky paint.

Why it's happened only upstairs I don't know - perhaps it's the heat accumulating on the landing.

[meow2222]

Sounds like the glue component failing. I'm going to try adding a little linseed oil to water based paint for damp situations, might help it last longer. Spirit based may do better.

If you dont wet porous walls before painting, the wall sucks liquid out of the paint when applied.

NT

[Stuart Noble]

It's unlikely to the pva, emulsion paint being entirely compatible with it. Whatever's causing it, oil based undercoat usually stabilises difficult surfaces, and is much more damp resistant. You can apply it over the existing emulsion after a rub down with coarse abrasive. The fumes can be a major problem when you're covering a large area though. I wouldn't want to sleep in the house that night.

[Stuart Noble]

The only issue with pva under emulsion is that the colour can be paler and show brushmarks if the seal is too complete. Nothing that would cause flaking

[Stuart Noble]

I don't think that's a worthwhile experiment. You can guess what happens to oil in water, and a mess is the most likely end result.

, might

You need to (relatively) seal porous walls to prevent that. Dilute pva prevents excessive glugging of moisture but is nowhere near a total seal

[meow2222]

Adding linseed to water based paints has been done since long before emulsion came along. No need to guess.

No, its just one way, and not the best option for a couple of reasons.

Not entirely, painting walls with pva first has caused several people problems.

Yes, on both counts, but since its likely to be a damp wall problem this would not be the wisest move.

or the next night. Or the next

NT

[Stuart Noble]

Whatever for? In that case you might as well mix oil paint with emulsion. Don't let chemistry get in the way.

[Nodge]

Thanks for all the comments.

Having given this some more thought I think it is probably a damp related problem. We are in the habit of hanging washing over the banisters on the landing to dry. There's a big radiator downstairs in the hall and the heat rises upstairs to the landing. Just for some reason the light green emulsion is affected where the darker green emulsion isn't. Think I'll just sand the wall down all over and paint again with a good quality emulsion and see what happens.

John

[meow2222]

to increase the range of substrates the paint will stick to

NT