As if it were unstable, but the plaster is not eternal. As a result of a fairly long operation or due to unprofessional technological application and other reasons, all this leads to the process of exfoliation, cracking. The applied paint in several layers may also be a very probable reason for this. In such situations, your intervention and repair are required, otherwise, it will simply collapse.
First of all, make sure that apply the material to a perfectly even surface, which should still be dry and clean. In no case should bold spots be allowed, as this will noticeably slow down and worsen the repair process. Also, do not mix two opposite solutions in the effects. As a result, there will be improper application, which guarantees poor quality. If you are dealing not with the walls, but with the ceiling, then first of all it is necessary to process smoked and fungal places. According to the standard, this is performed using a 3 percent solution of hydrochloric acid, after which the surface must be wiped with clean water.