644 HANDBOOK OF PHOTOGRAPHY 



utilized for the purpose of transferring coloring dyes instead of producing the wash-off 

 relief image as described before. A process based on this principle was introduced 

 commercially several years ago under the trade name of Pinatype. Material for this 

 process is obtainable from the Agfa-Ansco Company. 



Plates coated with gelatin and suitable as matrices for Pinatype-dye transfer are 

 available commercially, although the usual diapositi^'e plates fixed in plain hypo can 

 be equally satisfactory. 



The usual procedure is to sensitize the plates for 3 or 4 min. in a solution of 2 or 

 3 per cent of potassium bichromate and to allow them to dry in the dark. Although the 

 plates are not sensitive until Avy, the sensitizing should be carried out in subdued day- 

 light or under incandescent light. The plates so prepared should be utilized within 

 24 hr. 



The matrices must be printed from positives, and it is therefore necessary to first 

 print the negatives either by contact or by enlargement on positive plates or films of 

 the final size. 



The necessity of preparing first positive transparencies constitutes an additional 

 step in disfavor of this process. However, this particular step can be utilized to com- 

 pensate for exposure irregularities of the original negatives. The printing of the 

 bichromated plates must be made by contact with the positive transparencies in a 

 printing frame by means of sunlight or arc light. Since the image on the bichromated 

 gelatin is only slightly visible, it is best to place behind it, in a printing frame, a piece 

 of printing-out or proof paper to act as a photometer. The correct degree of printing 

 must be determined empirically and judged completely by the image on the printing- 

 out paper. After printing, the bichromated plates are to be freed of the bichromate 

 by washing in running water for 10 or 15 min. As the sensitivity to light ceases 

 immediately when the plates are immersed in the water, the washing can be carried 

 out under ordinary light. 



The Pinatype printing plates must be carefully identified by suitable markings, 

 or they could be slightly stained in the appropriate dyes to avoid any later mix-up. 

 It is best to let them dry completely before the final staining. The dye solutions are 

 made up in a concentration in accordance with instructions of the manufacturer. 

 The order of transfer to the final paper can be the same as with the Eastman wash-off 

 relief, viz., red, blue and yellow or blue, yellow and red or blue, red and yellow. It is 

 best, of course, not to transfer the yellow first, as otherwise the registration becomes 

 too difficult. The insertion of a thin Kodaloid sheet between the matrix and a final 

 paper for the purpose of obtaining correct registration will be found of great 

 advantage. 



The time required for staining the matrix the first time will be about 15 min. each, 

 after which each matrix must be well washed until no appreciable color is given off. 

 The type of paper and its preparation for final transfer can be as described under 

 Eastman wash-off relief. 



An alternative method consists in utilizing the positive transparencies as matrices. 

 With this method the positive transparencies fixed in plain hypo and well washed are 

 sensitized for 3 or 4 min. in a bath consisting of 



Ammonium bichromate 12J-2 g. 



Water 1000 cc. 



Ammonia 25 cc. 



The sensitized transparencies should then be put to dry in the dark and, when dry, 

 exposed to sunlight or arc light with the glass or celluloid sides toward the light source. 

 The amount of exposure to the light in this case also can be controlled by placing 

 behind each diapositive a sheet of printing-out paper. The diapositives must be then 



