The dirty surface of exfoliating, crumbling stone must be preconsolidated before it is cleaned. A mixture of Paraloid B72 and Dri-Film 104 is a very successful consolidant, but prevents direct cleaning of the surface by the poultice technique. Preconsolidation by impregnation with a mixture of limewater, acrylic emulsion (Primal AC33), and potassium siliconate (Silirain) produces no color change in the stone and allows poultice cleaning of the stone surface. The authors investigated the consolidative and protective effectiveness of the latter mixture in various concentrations of components. They found that, particularly in more concentrated formulations, it imparts cohesion and water repellency to sandstone and can even be used as a final consolidant. Their results were borne out in the in situ treatment of sandstone in the Palazzo Gaudenzi (Bologna). See also AATA 11-737 and 20-909 for related studies and 21-1334 for reference to proceedings. -- AATA