Chalky wall

[Koolpc]

My friend has a wall in her living room that has some areas that are chalky. Its an exterior wall. Previously painted fine, several months ago.

Everything seems ok outside on external wall.

What process would you recommend to rid the wall of these chalky patches.

Would Zinsser peel stop be a good product to use?

Any advice would be very welcome. Thanks

 

[opps]

When you say chalky, in the absence of images, it sounds like it might be efflorescence.

Is there a a fine powder on the surface that can be wiped off? If yes, it is probably the salt in the plaster coming to the surface. The salts are not harmful but need to be treated. They are often the result of the plaster becoming wet over a prolonged period.

The following site offers quite a bit of advice

David M. Kinsey – The effect of salts on dampness

Photos of both the inside and outside, with indicators to show which part relates to which would be helpful.

Regards.