A fine, white pigment composed of calcium hydroxide, and calcium carbonate. Lime white is produced by the long-term slaking of lime in water or air to form a thick, white, alkaline paste. It was used for fresco painting because it hardens to form a cohesive film without the aid of a binder. Lime white reacts with proteins, such as egg white, or casein, to produce a tough, insoluble film. Synonyms: St. John's white; bianco sangiovanni (It.). Museum of Fine Arts, Boston (2000). [J. Cassar, R. de Angelis]