In chemistry, it is a substance capable of forming salts with a base. In pictorial techniques, it may used as a anti-decayer. In restoration, acids are used in disinfecting and as solvents in operations of cleaning, obviously in weak concentrations due to the strong aggressiveness that characterizes it as may provoke irreparable damage (if incorrectly controlled) to the pictorial film. See acetic acid, hydrochloric acid, oxalic acid, salicylic acid, hydrocyanic acid, carbolic acid.