The Development of the Halftone Screen^ 



By Jacob Kainen 



Curator of Graphic Arts, U. S. National Museum 



[With 12 plates] 



The tremendous increase in the printing of pictures during the 

 past half-century constitutes one of the most important chapters in the 

 history of the graphic arts. While this phenomenal development in 

 picture printing came about as a result of public demand, the fact 

 remains that this appetite for pictures could never have been satisfied 

 had not certain mechanical instruments of reproduction first been 

 provided. And one of the most indispensable of such instruments 

 was the halftone screen. 



The halftone screen made it possible to translate the tonal values 

 and gradations of a photograph into dots of varying sizes so that 

 a plate could be prepared that would reproduce the original by 

 relief (letterpress) printing. Carried over into lithogi-aphy and 

 gravure, the halftone screen made important contributions to these 

 processes and played a key part in transforming them into giant 

 industries. 



The halftone screen, as it has been universally used since about 

 1895, is made up of two sheets of glass, each glass being ruled with 

 parallel lines etched and filled with black pigment and cemented 

 together at right angles so that the resulting single sheet of glass 

 shows a series of black lines crossing each other, with transparent 

 square openings like a fine version of a wire-mesh screen. When 

 placed before a sensitive plate in a camera the transparent openings 

 permit the light to pass through in proportion to the light and dark 

 areas of the object being photographed. Where the light reflected 

 from the object is low a small amount of light will pass through the 

 openings, which act like a pinhole camera, and where the illumination 

 is intense a larger number of rays will reach the sensitive plate. 

 In this manner the tones of the object to be printed are translated 

 into dots of varying sizes. 



1 Revised and expanded, by permission, from an article entitled "The Halftone Screen," 

 published as a brochure l»y R. R. Donnelley & Sons Co., Chicago, 111. 



409 



