Literature References: The bark of the cork oak tree, Quercus suber L., Fagaceae and to a lesser degree of Quercus occidentalis Gray, Fagaceae, indigenous to the African and European shores of the western Mediterranean. Constit. 35-60% suberin, 30-33% cellulose, 27-32% lignin; small amounts of cerin (a wax), fats, inorganic manganese compds, decacrylic acid. Suberin contains phellonic acid, suberic acid, phloionic acid, phloionolic acid, suberolcarboxylic acid, eicosadicarboxylic acid, stearic acid, cortic acid. Used to seal wine casks since antiquity: Theophrastus, Historia Plantarum 3, 16 and 17. Plinius (major), Historia Naturalis 16, 8, 13. Reviews and monographs: A. Klauber, Monographie des Korkes (Weber, Berlin, 1920); W. Herrmann, Kork in Ullmanns Encyklopädie der technischen Chemie vol. 10, (Urban & Schwarzenberg, Munich, 3rd ed., 1958) pp 634-637; G. B. Cooke, Cork and the Cork Tree (Pergamon Press, New York, 1961).
Properties: Pale tan, elastic mass. Floats on water. Specific gravity about 0.10 to 0.25 g/ml. Excellent insulator against heat and sound. Stable to heat up to about 100°. Unaffected by water, brine, dil acids, alcohols, bland oils. Attacked by concd mineral acids, strong alkali and ammonia, free halogens, hydrogen peroxide, ozone.
Use: Bottle stoppers, sound deadeners, heat insulators, life preservers, gaskets, linoleum manufacture, cork tile, bulletin boards, dart boards, inlays for shoes.