560 HANDBOOK OF PHOTOGRAPHY 



in clear water for 10 or 20 min. before attempting to apply the solution. The negative 

 should be moist for this afterwork, but should not contain too much water. Best 

 results are usuallj' obtained when the surface moisture has been removed by means of 

 lintless blotters or sponges. 



If care is taken with this method, few difficulties will be encountered. In order 

 that the desired intensification may be obtained, it is preferable to choose an intensifier 

 which does not stain appreciably. It may be desirable to dilute the intensifying or 

 reducing solutions to prevent too rapid action and to keep the treatment completely 

 under control. The main difficulty with this method of correction, especially for the 

 inexperienced, is one of keeping the applied solutions from spreading to undesired 

 portions of the negative. This difficulty may be reduced to a minimum hy working 

 over small areas and by removing the surface water from the negative. 



Yellow or orange dyes or well-diluted water colors maj^ be applied to portions of the 

 negative to obtain local reduction. These colors should be applied with a moist, 

 rather than wet, brush, and only a small amount of coloring should be added at a 

 time. The surplus water should be removed as soon as the desired area has been 

 treated. Through the use of successive applications, the densitj" may be built up to 

 the desired amount. A disadvantage of this system is that it is difficult to determine, 

 bj" visual inspection, the degree of photographic intensification which has been 

 obtained. 



Intensification may also be carried out bj^ darkening the negative with lead or 

 lithographic pencils, although this process is, perhaps, more properly to be regarded as 

 one of retouching than of intensification. 



A simple method of intensification which does not involve treatment of the partic- 

 ular negative may be effected by making a duplicate negative with a higher scale of 

 density than the original. Intensification may be carried out in the making of the 

 positive from the original negative and again when making the final negative. 



The use of a duplicate negative, having a lower contrast than the original, may 

 also be used for reduction. 



A simple method of reduction consists of removing some of the silver through the 

 use of an abrasive reducing paste applied to the image on the negative or through the 

 application of an abrasive pencil or rubber eraser. 



The contrast of a negative may be reduced by practically any desired degree 

 by printing from a negative a positive transparency, and binding this positive mask 

 with the negative. The mask may be made on sensitive material on a slow film or 

 plate and may have low or high contrast, according to the degree of masking required. 



Bibliography 



Periodicals: 



Haddon, a.: Potassium Ferricyanide and Ammonium Sulphocj-anide Reducer, Brit. J. Phot., 39, 



49, 60 (1892). 

 Piper, C. W., and D. J. Carnegie: Intensification and Redevelopment, Amateur Phot., 40, 336 (1904). 

 HusE, K., and A. H. Nietz: Proportional Reducers, Brit. J. Phot., 63, 580 (,1916). 

 NiETZ, A. H.. and K. Huse: The Sensitometry of Photographic Intensification, J. Franklin Inst., 



185, 389 (1918). 

 Krauss, H.: Reduction of Photographic Plates with Ferric Ammonium Sulphate, Z. iviss. Phot., 18, 



192 (1919). 

 BuNEL, L. J.: Harmonizing Negatives by Intensification with Chromium, Brit. J. Phot., 70, 625 (1923). 

 Crabtree, J. I., and L. E. Muehler: Reducing and Intensifying Solutions for Motion Picture Film, 



J. Soc. Motion Picture Engrs., 17 (No. 6), 1001-1053 (1931). 



Books: 



Wall, E. .1.: "Intensification and Reduction," Am. Photographic Pub. 



"The Tinting and Toning of Eastman Positive Motion Picture Film," Eastman Kodak Co. 



