Dynamic of moisture transfer in ancient plasters

The present research shows that it is possible to obtain, from mercury porosimetry, suction curves useful to describe how and how fast two touching porous materials exchange water. Suction curves correlate the mass water content with the capillary suction pressure, such a comparison making it possible to know, by means of a potential scale similar to temperatures, the water exchange possibilities between layers and also, through their first derivatives, the transfer velocity according to the saturation degree of initial and final materials. On the basis of these curves a hypothesis on the possible role played by the technological complexity of historical plasters as described in ancient treatises is put forward. A comparison between the suction properties of plaster sheets realised as ancient plasters, show that the stratification and the complexity may be a regulating system to prevent water penetration from the wall and the exterior.