CHAPTER XIV 



PRINTING PROCESSES 



By Keith Henney 



The photographic process culminates in the making of a positive print, either on a 

 transparent base for viewing by transmitted light or on a paper base for viewing by 

 reflected light. The negative is only an incidental and intermediate (although 

 extremely important) step in this process. The print is the final resvilt, and by the 

 print the photographer's efi'orts are judged as successes or failures. 



General Printing Processes. The Printing Method. — ^When the negative is made, 

 a tone reversal takes place, the bright portions of the object being reproduced in the 

 negative as dark portions and the shadows or dark parts of the object becoming light 

 or transparent portions of the negative. The reason for this reversal of tone is the 

 fundamental basis of present-day photography. Light so affects the negative mate- 

 rial that a metallic silver deposit of varj'ing thickness represents the image in the 

 processed negative. The high lights or brighter portions of the object are represented 

 by denser deposits of silver which absorb more transmitted light than the less dense 

 portions representing shadows of the object. 



When the print is made, the tone values of the negative are reversed so that the 

 dark portions, representing the high lights, become light portions in the print; and 

 the transparent parts of the negative, representing the shadows of the original, become 

 dark portions in the print. 



If the negative and positive have been correctly exposed and processed, the rela- 

 tions between the brightness of the brightest, the least bright, and the intermediate 

 portions of the original scene will be correctly reproduced in the final print. In the 

 ideal case the actual values of these brightnesses will be reproduced as well as the rela- 

 tions between them, but in general all that is expected of the print is that two portions 

 of the original, bearing a certain brightness ratio, will be represented in the print by 

 that same brightness ratio. Thus, if two portions of the original scene have a bright- 

 ness ratio of 3:1, these portions of the print should reflect light to the eye in a 3:1 

 ratio. 



Types of Printing Processes, and Their Characteristics. — Prints may be made, in 

 general, bj^ two methods: they may be placed in contact with the negative, when a 

 print having the same dimensions as the negative will result, or the positive material 

 may have the image projected on it from the negative so that the print may be smaller 

 or larger than the original, as well as the same size. If the print is to be reduced or 

 enlarged in size, compared to the size of the negative, the print must be made by 

 projection. 



Printing processes may also be classified as to the medium used for the print, viz., 

 paper sensitized with silver salts or paper sensitized with salts of other metals, or as to 

 whether the final print is in color or in monochrome, etc. In this chapter we are 

 concerned with monochrome printing on materials sensitized with salts of silver. 



The result usually desired is accuracy in portraying the original scene, not only in 

 perspective, but in tone values as well, considering that colors in the original are 

 reduced to black, white, and shades of gray, in the final print. But artistically the 



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