SPECIAL PRINTING PROCESSES 493 



the negative but smaller than the mask, and four registration marks on mask and 

 paper. 



A very beautiful effect, which is particularly delightful in the treatment of sunlit 

 water, a sunny landscape, or any subject in which a vibrating, shimmering eifect of 

 light is desired may be secured by very slight underprinting, by very slight under- 

 development, and by drying the print in a horizontal position on a sheet of glass or 

 other flat level surface. In this case the gum and pigment run slightly, giving a 

 peculiar blurring of the outlines which is not obtained in any other way or in any 

 other medium. This is a very difficult eifect to obtain, since it demands the most 

 exact timing throughout, but if secured, it has a remarkable charm. 



One of the finest characteristics of multiple gum lies in the extreme richness and 

 depth of the blacks obtainable, a quality in which gum rivals multiple carbon. This 

 effect, in both mediums, is due to the fact that we are looking through, rather than 

 at, successive layers of pigment suspended in a transparent medium, and, as in carbon, 

 the effect may be enhanced in a gum print by waxing and polishing. 



In conclusion: work systematically; keep a record of all you do; do not expect to 

 get a good picture with one printing; and do not overdo your local modifications. If 

 these recommendations are followed, success will result. 



Fresson Printing. — Fresson is, in effect, a revival of the Artigue process, which was 

 more or less used some 25 or 30 years ago, and like carbon and gum it depends on the 

 fact that a colloid film, when sensitized with a chromic salt and exposed to light, 

 becomes more or less insoluble in water. 



The paper supplied for this process consists of a sheet of paper carrying a basic 

 layer of some hard colloid — presumably either gelatin or glue — which has a high melt- 

 ing point. Over this is laid a stratum of softer colloid — probably gelatin^ — which 

 melts at about 96°F. and which carries a relatively heavy content of pigment. The 

 paper is supplied insensitive and is sensitized just before use by immersion in a solution 

 of potassium bichromate, being afterward dried and printed under a negative. At this 

 point the process diverges fi'om both gum and carbon, since, instead of being developed 

 by floating on cold water, as with gum, or by washing with hot water, as with carbon, 

 the printed paper is soaked for a short time in tepid water, is then laid face up on a 

 slanting surface, and is developed by pouring over it a soup of boxwood sawdust in 

 water. 



Advantages. — The process has a long scale of gradation, gives very rich blacks, and 

 has a beautiful absolutely matte surface closely resembling that of platinum. 

 The prints are absolutely permanent. 



The paper may be obtained in several different colors, and on several different 

 supports. 



Modifications of total contrast are verj^ easily made. 

 It is extremely easy to make modifications of local vakies. 



The process is very easy to work, requiring but little technical skill. Also there 

 is great latitude in handling. 



Disadvantages. — Fresson is a contact-printing process, requiring a very strong 

 light, and it is practically impossible to use it for enlarging. 



It is somewhat laborious to work, requiring a good deal of time for development if 

 the best expression of the process is to be obtained. 



The surface of the paper, both before and after printing, is very delicate and easily 

 marred, so finished prints must be handled carefully. 



The Paper. — As has been said, this is bought insensitive and, if stored in a cool dry 

 place, will kee^^^nost indefinitely, though the colloid gradually hardens with time, 

 requiring slightly warmer water for processing. It is advisable to store it flat, vmder 

 light pressure, to minimize its tendency to curl. The paper may be obtained in 



