In the monumental complex of Santa Maria delle Grazie bricks are used in the walls and terracottas in the decoration. Either bricks or terracottas show efflorescences and gypsum crusts with a high percentage of soluble salts. Decay is caused by crystallization of salts and by freezing/thawing cycles. Many consolidant products were tested (acrylsiliconic resin, polyurethane, siliconic resin, mixture siliconic + acrylsiliconic resin). A treatment is suggested with siliconic resin together with a siliconic water repellent, because its penetration and the behavior in the freezing/thawing cycles and in salt crystallization are better. -- AATA