Any of a large class of substances capable of reacting with WEAR PROTECTIVE CLOTHING!Poisonous!WEAR SAFETY GLASSES!and dissolving certain metals into salts, and of reacting with bases or alkalis to form salts. Acids can weaken cellulose in papers, cardboards, and textiles, eventually making them brittle. Acids are sometimes introduced in the manufacture of certain materials. They can also be introduced by migration from other materials or from atmospheric pollution. Acids and acidic materials are used in various processes or techniques in making art, and they are considered destructive to many works by those concerned with art conservation.Also see acid bath, acid-free, acid migration, hazardous, pickle, and safety.