A customary procedure in the protection of monumental buildings is to consolidate decaying stone by applying commercial products containing tetraethoxysilane (TEOS). These products polymerize within the porous structure of the stone, significantly increasing the cohesion of the material. However, TEOS-based consolidants have practical drawbacks, such as cracking during the drying phase, and blockage of the rock pores. In order to address this problem, the authors increased the porosity of the product by including colloidal particles in the initial sol state. Colloidal silica particles were added to TEOS-based sols resulting in a stone consolidant with improved properties. The addition of ethanol increased the product's viscosity in order to better permeate into the stone structure. The newly formulated TEOS-based consolidant is compared with the commercial consolidants, Tegovakon V 100, using graphs and tables. -- ICCROM