Chemical treatments for detackification and separation of over-sprayed paints and lacquers in spray booths without corrosion and pollution problems. Water used to wash the air in paint or lacquer spray booths in order to remove over-sprayed paint or lacquers is treated with alkali-metal zincates optionally further containing strong cationic polyamine to reduce the tackiness of paint and lacquer solids and thereby reduce the tendency of oversprayed paints and lacquers to adhere to walls, ceilings and floors of said spray booths and also to condition the paint and lacquer solids removed with the water so that they can be separated and the water recycled for further use in washing the air in the spray booth. Furthermore, very little corrosion of air ducts, walls and ceilings of said spray booths, due to concentrated salts from the added chemicals, is expected because both alkali metal zincates and cationic polyamines contain only trace amounts of chlorides and sulfates.