The paint has become a white powder
POTENTIAL REASONS OF THE PROBLEM
Moisture behind the surface of the color comes from three reasons:
a) lack of waterproofing and rising damp
b) lack of waterproofing from the back side of the wall
c) a series of hairline cracks in the plaster caused moisture to enter behind the paint
SOLUTION
1: Dismantling of the loose and good cleaning of the surface with brush. If there is moisture, let it dry before moving on with repairing.
2: Fill where required with STATUS 100% acrylic putty
3: Prime with Primer STATUS DUR SOLVENT
4: Apply STATUS ALL WEATHER in two coats