Water-repellent SL 90/10 penetrates well deep into the material. Organosilicon liquid exhibits high resistance to alkalis; Hydrophobic impregnation does not stick when dried; SL 90/10 is effective even when applied to wet surfaces of building materials; Quickly develops hydrophobic properties. After application, SL 90/10 water-repellent liquid reacts with atmospheric moisture or water contained in the pores of mineral building materials (natural stones, masonry, sand-lime brick, concrete surfaces, and mineral plaster), active components are formed and alcohol is released. These active components greatly reduce the water absorption of building structures. After treatment, neither the pores nor the capillaries are clogged and the substrate retains a high degree of vapor permeability.