To eliminate moisture from a wall, you first need to understand what is caused by it.
It can be rising damp ie that is the foundation or humidity caused by the incorrect ventilation of a room in the presence of activities that create moisture as in the case of bathroom and kitchen.
In case of rising damp we will intervene in the most serious cases to sheave the foundations and to create cavities, or, in less severe cases you can simply apply more plasters (lime mortar plaster) instead of cement plasters.
Mold on walls: harmful to health
It often comes in black gray or pinkish yellow color is caused by spores carried by the wind that find a favorable soil on damp walls of badly ventilated rooms.
Good ventilation and the absence of humidity are the best remedy for its formation and guarantee a healthy environment.