A proteinaceous, water soluble adhesive made from fish heads, bones and skin and other parts containing collagen, keratin or elastin. The agglutinating agents are removed by extraction with hot water, then cooled and dried to produce gelatin or glue. Varied production techniques can produce poor-quality fish glues. The highest quality is made from the swim bladders of sturgeons. It is clear, bluish white and very flexible. Isinglass is a fine glue made from a specific type of sturgeon. it is generally sold in narrow soft translucent strips. In general, fish glues are lighter in colour than hide glue and form a weaker adhesive bond. They dry to a hard, sandable surface and adhere well to glass, ceramics, metal, wood, and leather (Norland 1977). Fish glue is sold in liquid form and is used in painting and gilding. It is mentioned as one of the organic additives used for stucco marble preparation according to literature. See also: adhesive; glue. Synonyms: isinglass; sturgeon glue. Wittenburg (1999); Museum of Fine Arts, Boston (2000); Norland (1977). [J. Cassar, R. de Angelis]