SPECIAL PRINTING PROCESSES 495 



desired. Generally speaking, the cooler colors print more rapidly than the warm ones, 

 and a bone-dry paper will print more rapidly than one which is faintly damp. Using 

 the black paper, working with it bone dry, and working for normal results, the writer 

 makes a test on P O P, then prints the Fresson for about three-quarters of this proofing 

 time. 



Developing. — The print should be developed immediately after taking from the 

 printing frame, since there is the same continuing action with Fresson that there is 

 with carbon and gum. 



To develop, the print is immersed for 4 min. in water at room temperature, then 

 for 1 min. in water at 88°F. It is then laid face up on a smooth slanting surface, and 

 the sawdust soup is poured repeatedly over it. A convenient arrangement for this 

 apparatus was designed and made of sheet zinc by W. G. Houskeeper. It consists 

 of a semicylindrical trough about 18 in. long and 5 in. in diameter, supporting a 

 sheet of zinc which has had the edges bent up so that the soup will not run off them. 

 The trough has feet to keep it upright, the sheet has a lip which projects slightly 

 over the edge of the trough, and the upper end of the sheet is supported by a piece of 

 2- by 4-in. wood. An enameled cup from the 5-and-lO-cent store is used for 

 pouring. The exact angle of the support is of no great consequence. So long as 

 there is slant enough for the soup to run off freely, it is all right — an angle of 30° 

 with the horizontal is satisfactory. 



Development is continued until it has reached the proper point, when the print is 

 rinsed in cold water to remove any adhering bits of sawdust and to set the gelatin. 

 It is then hung up to dry; no further fixing or washing is necessary. The print will 

 dry somewhat darker than it appears while wet — this darkening is more apparent in 

 the shadows than in the high lights, so development should be continued until the 

 print seems a little lighter than it should be when finished. 



If for any reason it is not desired to develop the print at once, the continuing 

 action may be arrested by washing the undeveloped print in six or more changes of 

 water to remove the sensitizer. It may then be dried and developed in the usual man- 

 ner at any subsequent time. 



Unless printing has been so deep as to require the use of water at 96°F., it will 

 probably be found that the margins of the print, even though masked in printing, will 

 not develop clear but will retain more or less of the pigmented gelatin. Apparently 

 a slight amount of light actioa is necessary if absolutely pure whites are to be secured. 

 This residual tint is often very pleasing but may be removed with a brush if it is not 

 desired. 



For any given temperature of the soaking water, the print will develop to a certain 

 depth, after which continued pouring of the soup has no effect. If it does not develop 

 far enough after soaking at 88°F., the print may be placed for 1 min. into water at a 

 slightly higher temperature, after which development is resumed in the usual manner. 

 It is not advisable, however, to go above 94 to 96°F., since at this temperature the 

 pigmented film will probably strip entirely from the paper, and even if it does not do 

 this, the high lights of the picture will probably flake off, leaving blank spaces. If 

 96°F. will not bring the print up to the proper point, it is seriously overprinted and 

 should usually be thrown away, though it may sometimes by salvaged by brushing 

 with a soft brush. This treatment, however, is likely to result in unsightly scratches 

 on the surface of the print. 



Variations in Contrast. — For normal sensitizing, the softest contrast is obtained 

 when the paper is printed to such a depth that it will develop satisfactorily after 

 1 min. of soaking at 88°F. Deeper printing, up to double the normal time, with the 

 use of a warmer soaking water, up to 96°F., gives marked increase of contrast; this 

 latter technique tends to give a grainy texture to the print which may be undesirable. 



