Experiments of consolidation carried out on sandstone in an advanced state of deterioration show exfoliation of surface skin and an incoherent stone layer underneath. Silicones, acrylics (and silicone-acrylic mixtures), epoxies and polyurethanes were applied both on monuments in situ and on samples in the laboratory. Depth of impregnation, porosity, mechanical properties and water absorption were measured. Wetting-and-drying weathering cycles were employed to assess durability of the treatments. Aesthetic effects of impregnation are discussed.