Performance evolution of hydrophobic treatments for stone conservation investigated by MRI

H-1-MRI has been applied to the evaluation of the performances of a hydroph obic polymer (Paraloid B72), widely used for the conservation of monumental buildings and other stone artifacts. By this technique it has been possibl e to visualize the water diffusion in a treated rock material (Pietra di Le cce, a highly porous Italian biocalcarenite) and then indirectly the spatia l distribution of the polymer in the rock. The effects of wetting-drying cy cles on the hydrophobic efficacy of the acrylic polymer in the inner layers of the rock were also studied. A notable decrease in the water-repellence inside the stone was detected and attributed to a loss of adhesion of the p olymer to the substrate, promoted by the action of water. (C) 2001 Elsevier Science Inc. All rights reserved.