The effect of various silicone-based products on three different types of volcanic tuff, two from Germany (Ettringer and Weiberner) and one from Poland (Filipovice) was studied. The products tested were one consolidant (Wacker, OH), applied at different concentrations, and three water-repellent materials (Elastosil, Silak and Ahydrosil Z). The changes in porosity, water absorption, and other physical characteristics were measured and interpreted on the basis of the tuff/applied product interaction. Artificial weathering cycles were also carried out, and the results obtained are discussed.