232 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1941 



Casein plastic.— Th& discovery of the tough, insoluble, hornlike mass 

 produced by the action of formaldehyde on milk casein is said to 

 have been made by two men who were looking for a composition ma- 

 terial to replace slate for blackboards. These two men, Wilhelm 

 Krische and Adolph Spitteler, began production of casein plastic 

 about 1900 in Germany and France, respectively, using the trade name 

 Galalith, meaning milk stone. It was 1919 before successful produc- 

 tion in America was realized, and its use has been limited because 

 of the marked variations in climate throughout the year, which lead 

 to warping and cracking of this plastic. Its use is confined to small 

 articles like beads, buckles, buttons, game counters, novelties, and 

 trimming accessories. 



Cellulose acetate plastic. — A period of very active development of 

 new plastic materials in America started with the appearance of 

 cellulose acetate in the form of sheets, rods, and tubes in 1927. The 

 firm which pioneered in the development of pyroxylin plastic also 

 introduced cellulose acetate plastics to the American market. This 

 was accomplished by a combination in 1927 of the Celluloid Co. with 

 the Celanese Corporation, already a large producer and consumer of 

 cellulose acetate for rayon manufacture. In 1929 the first cellulose 

 acetate molding powder was marketed for use in compression molding. 

 The appearance of the injection molding press in the early thirties 

 greatly increased the speed with which molded articles could be pro- 

 duced with this thermoplastic material. Cellulose acetate plastics and 

 molding powders are now available from several commercial sources 

 and have outstripped the cellulose nitrate type in the quantity and 

 dollar value of annual production. 



Cellulose acetate very early found use as a safety photographic 

 film to replace the hazardous cellulose nitrate product. Many of the 

 applications of this plastic — for example, protective goggles, oil gages, 

 screw-driver handles, and flexible window material — ^have been 

 brought about by the safety factor introduced by its high resistance 

 to impact. It is employed in practically every make of automobile 

 and the total number of acetate parts involved is well over 200, includ- 

 ing such items as knobs, handles, switches, escutcheons, steering 

 wheels, instrument panels, horn buttons, and dials. Some of the 

 trade names for cellulose acetate plastics are Lumarith, Plastacele, 

 and Tenite I. 



Urea-formaldehyde plastics. — The appearance of the urea-formal- 

 dehyde resinous molding compound on the American market in 1929 

 meant the extension of unlimited color possibilities into the field of 

 thermosetting molding. Two such urea molding powders, Aldur and 

 Beetle, became available that year, while another, Plaskon, was mar- 

 keted in 1931. Extensive use of urea plastics in the illuminating in- 



