Adhesion and impact resistance properties of hard finishing masses prepared from cement – sand mixtures, gypsum or chalk containing, as a binder organo – or water – soluble methacrylic polymer have been studied. The adhesion and impact resistance of hard finishing masses for stone change equally dependent on the mass composition and conditions of temperature-moisture storage of monuments. The adhesion to porous substrates and the impact resistance of the hard masses increase with them or with using a polymer that is a surface- active substance. A sharp decrease in the strength of the hard finishing masses exposed to heating at high temperatures or on freezing the samples, especially in a humid state, is observed.