isinglass, gelatinous semitransparent substance obtained by cleaning and drying the air bladders of the sturgeon, cod, hake, and other fishes. Isinglass is manufactured in Russia, the United States, Canada, Brazil, Indonesia, the West Indies, and the Philippines. It is used in the clarification of wines and beers, as a stiffening for jellies, in court plaster, and in glues and cements. The name isinglass is also commonly applied to thin sheets of mica and sometimes to a gelatinous substance obtained from certain seaweeds.