Influence of paints on drying and salt distribution processes in porous building materials

Paints are widely used as finishing coats on all kinds of buildings. Aiming at a better understanding of how paints influence salt decay processes, experiments were performed on painted and unpainted specimens: (a) crystallization tests on specimens composed of a plaster on brick substrate; (b) drying experiments on stone specimens, monitored by means of a two-dimensional magnetic resonance imaging technique. The results of these experiments suggest that: (i) paints tend to increase the presence of moisture and salt deposition on or close to the surface of walls; (ii) the salt-accumulation behaviour and related features of different plasters/renders may be differently affected by paint layers.