SPECIAL PRINTING PROCESSES 473 



richness and transparency akin to that which the painter secures by repeated over- 

 paintings of a transparent color. 



Double Transfer. — This method is used in three-color work or when the print must 

 be the right way around and must possess very fine detail. It is not, in general, useful 

 to the pictorial worker, since it not only introduces an extra — and rather delicate — 

 operation, but limits the choice of transfer paper to a comparatively smooth 

 surface. 



To make prints by double transfer, secure a sheet or several sheets of the tem- 

 porary support, which is sold by the dealers in carbon materials, together with a bottle 

 of waxing solution and several sheets of double transfer paper. The temporary sup- 

 port is carefully cleaned with warm water, dried, given a coat of the waxing solution, 

 and then lightly polished with a tuft of cotton. The print is transferred to this and 

 developed on it as described above. When this operation is completed, the well- 

 soaked double transfer paper is squeegeed to the print and allowed to remain under 

 pressure, between blotters, for a few minutes. It is then stripped off the temporary' 

 support and allowed to dry in the usual manner. 



Prints on Ivory. — Carbon prints may be made on ivory, porcelain, celluloid, and 

 other materials, using the single transfer method. The support to be used may be 

 coated with the gelatin-chrome alum solution, described above, by dipping and should 

 then be dried in a dust-free atmosphere. The subsequent operations are as already 

 described. 



Transparencies. — Very fine transparencies for the making of enlarged negatives 

 may be made by carbon printing, the great advantage of this method being that the 

 gradations of the original negative are faithfully reproduced with no danger of loss 

 through incorrectly estimating the exposure and development, as often happens when 

 making such transparencies on dry plates or films. 



Instead of transfer paper, a piece of ground glass, which has been well washed with 

 soap and water and thoroughly rinsed, is used. All the operations are as already 

 described, except that the tissue should be printed about four times as long as for a 

 print on paper. The tissue is transferred to the grovmd side of the glass, which needs 

 no special preparation. A special transparencj^ tissue is sold for this purpose, but the 

 writer prefers to use the regular Ivory Black. If a slight grain in the large negative is 

 not objectionable, the transparency may be used as soon as it is dry, but if grain must 

 be avoided, the transparency should be flowed with some ordinary negative varnish, 

 which will eliminate the grain of the ground glass. 



Miscellaneous Notes. — Frilling of the print during development may be caused by 

 (1) no safe edge, (2) failure to use a freshly cut edge on the carbon tissue, (3) exces- 

 sively hot water used at first in developing, (4) stripping before the gelatin has been 

 sufficiently softened, (5) an alkaline sensitizer, (6) the use of excessively hot water for 

 developing, (7) development forced with excessive alkali in the developing water, (8) 

 excessive soaking of the print before squeegeeing to the transfer paper, (9) insufficient 

 pressure during squeegeeing, (10) failure to allow the print to remain long enough in 

 contact with the transfer paper before development. Blisters may result from (3), 

 (4), (5), (6), or (7) or from allowing air bubbles to remain between the print and the 

 transfer paper, when squeegeeing. Frilling or blisters may also result from the use of 

 insufficient gelatin on the transfer paper or from the use of an excessively hard gelatin 

 such as that on a supercoated bromide paper, but in this case the failure is more likely 

 to be a definite tearing away of the print in large areas than a true frilling or blistering. 

 It should be noted that the failure due to an excessively alkaline sensitizer or to the 

 use of excessive alkali in the developing water is more likely to be a breaking down 

 of the gradations in the high lights — a sort of corrosion of the thinner portions of the 

 print — than an actual frilling or blistering. Handling the dry carbon tissue — either 



