Condensation?

[philipb]

We have patches of white spores forming on a kitchen (exterior) wall. They are appearing in sections where the paint has bubbled up (almost blister-like). The pattern is similar to a snail's trail. They can be wiped clear, but then reappear.
The section of wall is between our back door and the kitchen window, which has a radiator underneath it.
Does this sound like condensation? (incidentally the kitchen widow is largely condensation-free).
Any thoughts/tips gratefully received!

 

[Carpenter]

Sounds like efflorescence or salts leaching through the paint. Is this new plaster? If not you may want to investigate a possible leak? (Is this forming at high or low level) Either way the only solution is to rub back the affected areas with a sanding block and spot prime with Dulux Sealapore akali resisting primer. When dry touch up with emulsion.

 

[philipb]

Hi Carpenter... it's not new plaster, but is relatively new paint (we repainted after buying the house in the summer). The patches have formed at a height of about 1.5-2m. Have since filled a couple of small holes on the outside of the wall, which could have well been letting in moisture (especially given the recent lousy weather). Will follow your redecoration tips and keep an eye on things. Thanks for your help.