Abstract

Class, Jay B. (Hercules Incorporated). Natural resins are solid, amorphous, usually transparent or translucent organic substances that originate from plant secretions. They may be obtained directly as tree or plant exudates, collected by hand or below the ground, or mined from underground deposits. Shellac is refined from insect secretion which coats twigs of a host tree. The resins may be altered by methods of isolation, or modified in production to increase their industrial utility. In this article, the resins are discussed in five groups. Rosin and modified rosins are commercially the most important natural resins, with an annual production of almost a million tons. The isolation of rosin from pine gum, pine stumps, and tall oil is discussed, as well as properties, composition, chemical reactions, and derivatives. Principal uses are described, such as paper sizing, printing inks, and adhesives. The origin, properties, and uses of traditional natural resins are described, with special emphasis on resins that are available in the United States. These are Manila copal, pontianak, dammar, East India resins, gum elemi, sandarac, and mastic. Resins with limited availability, such as kauri, congo, accroides, and amber are also discussed. In a section on natural resins in medicines, flavors, and fragrances origin, composition, and uses are described for balm of Gilead, balsam of Peru, balsam of Tolu, copaiba, gum benzoin, guaiac, myrrh, olibanum (frankincense), and storax. Properties are described for the asphaltites, such as gilsonite, glance pitch, and grahamite, as well as for Utah coal resin. The history, cultivation, production, and composition of shellac are discussed. Uses in protective coatings, pharmaceuticals, candy and fruit coatings, and electrical applications are described.