Cracks or small cracks

In old masonry or in new plasters before painting we observe capillary cracks and small cracks.

Possible causes

Poor quality or old-fashioned masonry that has been maintained for years.
Plasters do not have the right composition or are applied too thick or in the wrong way.
The humidity of the surface when it was very high.
The masonry is exposed to weather conditions with large temperature fluctuations or frost conditions.
The paint used does not show elasticity and good resistance to temperature change

Solution

As a precaution, the above causes that cause and enhance the phenomenon should be reduced and then the new surface should be plastered with the elastomeric pellet putty and primed with water primer or solvent primer. Then apply together acrylic insulation & paint, which has excellent elasticity, bridges capillaries and microcracks and offers enhanced protection against mold.
Suppressively, the painted surface should be cleaned of old paints, plastered with, primed and painted with the above suggested painting systems.