discoloured ceiling

[happywitchie]

I gave my ceiling two coats of a premium quality emulsion paint yesterday and when I looked this morning, there are browny/yellow patches showing through all over the ceiling. I sugar-soaped the ceiling before I began. The ceiling has paper on it and was last painted 5 years ago. The paint is quite expensive so I don't want to keep coating the ceiling just in case these mystery stains keep penetrating. I don't know what they could be. Am I going to have to strip the paper and re-paper? Really don't want to have to do that!

I would appreciate any advice offered.

Thanks

[painter]

1 of 2 things.

A stain bleeding through (i.e. nicotine, water etc.).
If it is a stain bleed through, it is most likely a water-soluble stain. In which case, I would use an oil or shellac based primer.

Or

Surfactant leaching.

Surfactants are soaps formulated into most latex paints. Under the right (depending on how you look at it, wrong) conditions - usually high humidity and low temperatures, the surfactants can leach out causing brownish spots to appear.

If it is surfactant leaching, you should be able to wash it off with a damp sponge. There is only a limited amount of surfactant in paint, and it usually does not stain the paint once it is removed.

If I were a betting man (considering you mentioned soap), I would say it’s a case of surfactant leaching. Which may be the better problem to have.

Good luck.

[happywitchie]

Thanks for your reply. It may have been surfactant leeching - I will never know.

I was using Crown Indicoat paint (a new fangled paint that is pink in the tin but dries white). After posting here, I did some research online and found that other people also got brown patches after using this paint. So I ended up painting over it with my usual Dulux emulsion and my ceiling is nice and white now.

The moral of the story is to stay away from new paints until they've been around long enough to be proven.