COLOR PHOTOGRAPHY 659 



graphed with the idea in view of making several duplicate color transparencies, it 

 is best to resort to another color process which permits any number of duplicates to be 

 obtained. This is the Finlay color process. 



Finlay Process. — The Finlay color process is identical with the previously described 

 screen color plates with the exception that the color-screen elements are independent 

 of the panchromatic negative emulsion and are carried to a separate glass plate (taking 

 screen) where the color elements are disposed in geometrical pattern in small squares 

 similar to the Duf ay color film. The usual procedure is to place the color-taking screen 

 in contact with the plate carrying a panchromatic emulsion and expose the two 

 together in an ordinary camera with the glass side of the taking screen toward the 

 lens. The contact between the taking screen and the panchromatic emulsion must be 

 fairly good, otherwise diffusion and poor color results will be obtained. 



Suitable panchromatic plates for the above purpose are manufactured by Ilford in 

 England and by Eastman in the United States; they are marketed as a special P^inlaj^- 

 Ilford panchromatic plate and Finlay-Eastman panchromatic plate. Suitable com- 

 pensating filters for different types of lights are also available with this process. 



After exposure, the panchromatic plate is removed from contact with the color- 

 taking screen and developed in the usual manner. When examined with a magnifying 

 glass, the developed negative plate shows an image broken up into very small squares 

 very similar to the usual photomechanical process screen used for half-tone printing in 

 book illustrations. 



If now a positive transparency plate is placed in contact with the negative and 

 printed under artificial light in intimate contact in a printing frame, the positive image 

 that is obtained will also have the image broken up into minute squares, just as the 

 original. 



To reproduce the original colors, the positive plate is now placed in intimate con- 

 tact with a positive viewing screen of very much similar composition to the original 

 color-taking screen and having color elements of exactly the same size as the original 

 color-taking screen. 



The operation of registering the positive plate with the positive viewing screen 

 requires a little experience, but it represents no great difficulties. When satisfactory 

 registration has been obtained, as depicted by natural colors showing up satisfactorily 

 by transmitted light, the two are permanently bound together. 



It is obvious that any number of positive prints can be obtained in this way from 

 the original negative on ordinary positive plates, each of which can be assembled 

 together with its own viewing screen, assuring identical results. 



There are certain definite advantages with the Finla}^ color process as compared 

 with the other additive process alreadj^ described. These advantages consist mainly 

 in the facts that the negative emulsion is a standard panchromatic emulsion of very 

 high gradation and an appreciable latitude of exposure is permissible since one is not 

 concerned with the amount of emulsion left unexposed, this balance of emulsion not 

 being used to reproduce a positive by reversal methods. 



For the purpose of color reproduction on paper, color-separation negatives from 

 the Finlay color transparency can be made up also by rephotographing the trans- 

 parency through sharp separation filters such as the Wratten Nos. 29, 50, and 61. 

 However, the most satisfactory method consists in utilizing a special blocking-out 

 screen manufactured exclusively for the purpose of photomechanical reproduction, 

 without any additional use of color-separation filters. Two of these block-out filters 

 are available. One of the screens is used for both the red and the blue printer and the 

 other for the yellow printer. 



Because of better emulsion qualities permitted with the Finlay color process and 

 the use of block-out screens, color reproduction on paper from this process can be 



