1.1 This practice covers non-abrasive surface cleaning of architectural sandstone to remove grease, dirt, loose material, and surface deposits such as soot, fly ash, hydrocarbon residues, and algae and other biological growth in preparation for the application of water repellent coatings. Procedures include broom cleaning, vacuum cleaning, air blast cleaning, water cleaning (and detergent water cleaning), and chemical cleaning.1.2 Limitations - This practice is intended to clean ar