230 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1941 



tant factors in this application, but its susceptibility in the trans- 

 parent form to ultraviolet light resulted in rapid deterioration of 

 these sheets. Typical applications of this plastic include bag 

 frames, brushes, buckles, clock dials and crystals, drafting instru- 

 ments, fountain pens, piano keys, shoe eyelets and lace tips, spectacle 

 frames, toilet seats, tool handles, toothbrush handles, toys, and covers 

 for wooden heels. The contributions of this first synthetic plastic to 

 the plastics industry have been extensive and lasting. It not only 

 paved the way for the advances which have been made in formulation 

 and pigmentation of all thermoplastics, but it also supplied much of 

 the mechanical and operative means of manufacture and fabrication. 

 It was the real pioneer in the development of the market for plastics 

 and in many of their uses. 



Shellac 'plastic. — The next plastic to become of importance in this 

 country was shellac molding composition. Shellac is of natural 

 origin, being produced by an insect which lives upon certain trees 

 in India and southern Asia, and has been known and utilized for 

 many centuries for various purposes, such as a component of sealing 

 waxes, polishes, and varnishes. In 1888, Emile Berliner had worked 

 out the details of the method that made it possible to engrave a sound 

 groove on a flat disk, but means of duplicating these recordings in 

 large numbers remained to be perfected. He tried both cellulose 

 nitrate and hard rubber, but neither of these materials was satisfac- 

 tory for his purpose. In 1895 he turned to a plastic composition 

 containing shellac as a binder, and soon the technique of molding 

 shellac-base phonograph records was under full development. It 

 remains today the largest single outlet for shellac in the plastic 

 molding field. The properties which make it especially suitable for 

 the manufacture of records are ease of molding, toughness, hardness, 

 fidelity of reproduction, low cost, and the possibility of reusing the 

 scrap material. Developments in the past 20 years have been pri- 

 marily in its application as a resinous binder for cloth, paper, silk, 

 mica, and other electrical insulating components. 



Bitumen plastic. — The third plastic to become industrially impor- 

 tant in America was the bituminous type, more commonly known as 

 cold-molded. Emile Hemming was the pioneer in its development 

 in the United States and introduced it on the market in 1909. The 

 raw materials used in the preparation of cold-molded plastics are 

 asbestos, asphalts, coal tar, stearin pitches, natural and synthetic 

 resin, and oils. The asbestos in the proportion of 70 to 80 percent 

 contributes the body of the material and the bituminous or resinous 

 ingredients in the proportion of 20 to 30 percent function as the 

 binder. The molding is done at or near room temperature, hence the 

 name cold-molded. The pieces are removed immediately from the 



