A method of processing porous building materials in an impregnation chamber is disclosed. The are placed into the chamber and subjected to a vacuum for about 10 minutes. Then a mixture of a dye with a hydrophobic impregnant (liquid) is sprayed into the chamber at the pressure of 6 to 30 atm, thereby creating gas-like misty environment. The material is subjected to the misty environment for 0.5 to 10 minutes while gradually increasing the pressure in the chamber until the atmospheric pressure. Latex or acrylic based dyes with diffusion qualities and silicone based hydrophobic liquids possessing film qualities are used. Materials processed include bricks, cement and qypsum-based materials, natural stone, wood and timber based products, and ceramics.