DESTRUCTIVE FACTORS CAUSING DETERIORATION OF PAINTS ON BUILDINGS WALLS

Durability of the surfaces depends on prevailing climate effects and on a complex of physical and mechanical values of the materials used. Damage of external walls depends on a high moisture content. One example of such damage is damage due to direct water penetration in walls. The other negative effects of a high moisture content are impaired heat insulation and accelerated degradation. The investigation of the external layer of walls and durability of different paints is carried out in the present article. In case of system "paint film - the wall being painted" two opposite processes take place: water flow rate from outside towards the wall, and water vapour flow rate of the wall to outside. For the wall to be painted, optimum selection of paint is necessary. Water vapour accumulated in the wall, when disturbed from escaping through a very dense film might cause blebs, or tear off the whole film or its parts. It was foreseen before investigations of paints on durability that theoretical attitude - low vapour resistance - low rain penetration - can be insufficient evaluating paints durability. During investigation the changes of surface layer, showing decrease in adhesion between paint and surface were fixed. After the investigations in climate chamber were finished and the results were calculated, the reliability of theoretical statement was verified.