482 HANDBOOK OF PHOTOGRAPHY 



The sensitizing may be carried out in an ordinary room or by the Hght of a 100-watt 

 Mazda lamp, since the paper is only slightly sensitive while wet. 



Brush and graduate should be well washed under the faucet immediately on 

 completion of sensitizing. 



Printing. — As has been said, a strong light is required for printing, and, as with 

 any paper, the time will depend on the density of the negative and on the character 

 of the result desired. It is the writer's practice to make negatives somewhat softer 

 than the average, and in unobstructed July sunlight or 15 in. from a 110- volt 15-amp. 

 twin carbon arc, using White Flame carbons, the printing time ranges between 2 and 

 5 min., with the sensitizer for average results. The printing time will vary slightly 

 with the different sensitizers, those for stronger prints requiring somewhat more time 

 and those for soft prints a little less. If the carbon-arc lamp is used. White Flame 

 carbons are preferable to the Panchromatic. 



When printed, the image will appear brownish yellow on a yellow ground, but it is 

 not distinct enough to serve as a guide to timing, and test strips should be printed and 

 developed before printing the full sheet. 



Developing. — The developer is made up as follows: 



Water, warm 1500.0 cc. -48 oz. 



Potassium oxalate 500 . g. 1 lb. 



In some localities, where the water is very hard, it may be advisable to make this 

 up with distilled water, but as a rule this is not necessary. 



The developer is ordinarily used at room temperature, i.e., from 65 to 80°F., 

 moderate variations in temperature having little effect on the results. A tray a size 

 larger than the print should be used, the developer being poured into this to a depth 

 of 32 i^- or so and the print being slid in face up, so that the developer covers the print 

 with an even sweep. If there is any stoppage so that the print is not evenly covered, 

 development marks may occur at normal temperatures and are certain to result when 

 the developer is used warm. 



Development should take place immediately after printing since, although there is 

 no continuing action as there is with bichromated colloid processes, the paper is very 

 hygroscopic, and if it absorbs moisture from the air, the print will have degraded 

 high lights. 



At normal temperature, development will require 3 or 4 min. and should be con- 

 tinued until it has gone as far as it will. In the case of an overprinted print, it is 

 sometimes possible to save it bA^ withdrawing it before development is complete, but 

 this is uncertain and should not be depended upon. An undertimed print cannot be 

 forced after development has begun, though if underprinting is discovered before 

 development, the print can sometimes be saved by warming the developer. 



Clearing. — The clearing bath is 



Water 2000 . cc. 60 oz. 



Hydrochloric acid (c.p.) 35.0 cc. 1 oz. 



The print should be given three successive baths of the above strength, after which 

 it is washed in running water (or in half a dozen changes) for a few minutes and is 

 hung up to dry. Clearing must be thorough, to remove all the iron salts from the 

 paper, or the print will gradually darken on exposure to light. 



Increased Contrast. — If sufficient contrast cannot be obtained by varying the 

 sensitizing solution, as given above, still further contrast may be obtained by printing 

 to normal depth but in a very weak light, so that a long time is required. If still more 

 is desired, it may be secured by overprinting and by adding a small amount of potas- 

 sium bichromate to the developer. It is iinpossible to give precise instructions as to 



