478 HANDBOOK OF PHOTOGRAPHY 



has a slight intensifying action on the bromide print, and allowance for this should be 

 made in the use of the control bath. Owing to mechanical causes, the limit to this 

 use is about six carbros to each bromide. 



If the nontransfer method is used, there are three possible courses. 



1. The residual silver image may be completely removed with Farmer's reducer. 

 In this case the final result is a pure carbon print. 



2. The residual silver image may be redeveloped with sodium or barium sulphide 

 (not sulphite) to a brown, in which case the result is a brown image underlying the 

 pigment image of the carbon and adding strength as well as a warm color to it. 

 Barium sulphide is preferable to the sodium salt, as it gives a cooler, richer brown, but, 

 if it is used, care must be taken to swab off the scum that settles on the face of the 

 print and to give a final rinse after this is done. If the silver image is thus redeveloped 

 to a brown under a carbon image in Ivory Black, the whole being on a buff stock, the 

 richness and color of the result are very desirable in the case of portraits with a dark 

 background or in the case of sunny landscapes. 



3. The residual silver image may be redeveloped to a black, using any ordinary 

 developer, and may then be left that w&y or maj^ be made the basis for multiple 

 printing. 



Whichever one of these final treatments is selected, the carbro print should always 

 be dried before the aftertreatment since, if this is done, there is less danger of blisters 

 and frilling. 



Multiple Prints. — The making of multiple prints by nontransfer carbro is exceed- 

 ingly simple and easy. The bromide print is redeveloped to a black with any ordinary 

 developer; it is weU washed and dried; and a second printing of carbon is placed on the 

 first, using the bromide-carbon print exactly as the original bromide was used. Obvi- 

 ously, there is no need of any special registration, since this is automatically taken care 

 of by the bromide print, i.e., by the silver image which reacts with the sensitizer to 

 insolubilize the gelatin of the carbon tissue. It is, of course, apparent that, provided 

 there is no slipping during squeegeeing, registration will be perfect even though the 

 bromide print may not have shrank back to its original size. In the writer's opinion, 

 the chief merit of carbro lies in the extreme ease with which the great richness of 

 multiple carbon prints may be attained in large sizes. 



Prints in Colors.— It is possible with carbro to produce prints in arbitrary combina- 

 tions of colors. Thus, if a landscape is to be printed and it is desired to have the 

 foreground in green and the sky in blue, the foreground in the bromide print is bleached 

 out, using an ordinary ferricyanide-bromide bleacher, and applying it with a brush. 

 Then a carbro print is made from this semibleached bromide, using a blue tissue when 

 only the sky is printed. Then the bromide is redeveloped to a black, and the sky is 

 bleached out, after which the foreground is used as a basis for a green carbro. In 

 general, however, the results of this technique are extremely unsatisfactory, being 

 harsh and unconvincing. However, it is often the case that multiple prints in different 

 colors are very pleasing, if the colors are so chosen that they harmonize, the various 

 colors being used merely to modify the tone of earlier or later printings, as was 

 suggested for carbon work. 



Platinum Printing. — At the time of writing, there is no commercial platinum paper 

 on the market, but the operation of preparing homemade sensitized material, together 

 with the subsequent printing and processing, is so extremely simple and easy as to be 

 well within the capability of even the least experienced amateur. The results 

 obtained are in many respects so far superior to those given by any other photographic 

 printing medium as amply to repay the slight effort involved. 



Advantages. — The prints are absolutely permanent. If properly developed, 

 cleared, and washed and if made on a good grade of linen paper, platinum prints will 

 remain in new condition unless the paper support is destroyed mechanicalh^ or by fire. 



