Powderyand Damp Looking Stain on Newly Decorated Wall DIY hints, tips and solutions to the removal and repair of marked and stained areas

[Tommyfromhull]

Hello,

We recently decorated our home and patched up some of the rough plaster on an interior wall next to some verticals radiators. After it dried, we then painted the walls and noticed these strange patches appearing. It looks damp, but it is not an exterior wall, and the paint is flaking off. We patched up some part of the walls and painted them the same and these patches are not showing, only in this area.

Any ideas?

Thanks,
Tom