454 HANDBOOK OF PHOTOGRAPHY 



Toning by Direct Development. — When developers of a special composition are 

 used and the developing time is shortened or the solution diluted, a coloring of the 

 image is noticed; this usually is brownish. Here again some papers have properties 

 which yield themselves to these modifications of development more than others. 

 These are the chlorobromide papers that yield warm olive tones even in ordinary 

 developers, and some of the chloride papers. Most chloride papers, especially those 

 used for commercial and photo-finishing purposes, are blue-black in tone when devel- 

 oped in the recommended formulas. Bromide papers, as a rule, are not readily 

 adaptable to toning by direct development. 



The reducing agents used in a developing formula and their proportions to one 

 another play an important part in the determination of the final color of a print. 

 It must be remembered that an agent such as hydroquinone has a tendency, when 

 used without any other agents, to yield warm tones, especially in the presence of fairly 

 large quantities of potassium bromide. Metol, on the other hand, besides having 

 soft-gradation-producing characteristics, generally makes the tones of prints black 

 or blue-black. 



In most photofinishing establishments contact prints with a blue-black tone are 

 desired, and these result from using a developer having a high energy factor, i.e., 

 one having a large proportion of alkali or energizer and properly balanced amounts of 

 metol and hydroquinone. Such a developer is of the following composition and may 

 be used for contact and bromide papers when cold blue-black tones are desired. 



Stock Solution (Agfa 103) 



Hot water (125°F. or 52°C.) 750 cc. 24 oz. 



Metol 3.5 g. 50 gr. 



Sodium sulphite (anhydrous) 57 g. 1?4 oz., 50 gr. 



Hydroquinone 11.5 g. M oz., 55 gr. 



Sodium carbonate (monohydrated) 78 g. 23-2 oz., 35 gr. 



Potassium bromide 1 . 2 g. 18 grains 



Water to make 1 1. 32 oz. 



Dilute 1 part stock solution with 2 parts water. 



Chloride papers: Normal development time, 1 min. at 70°F. (21°C.). 



Bromide papers: Normal development time, IH to 2 min. at 70°F. (21°C.). 



A chlorobromide paper when developed in such a formula will have a tendency to 

 produce rich blacks, although the medium tones will be more olive in color, especially 

 if through use the developer has been allowed to accumulate an amount of bromide. 

 By reducing the amount of metol in such a formula, the warm-toned results will be 

 even more pronounced. If the solution is diluted in order to control the rate of 

 development, still warmer tones wUl result. 



There are other reducing agents, which, when used in the developing formulas in 

 the proper proportions, will yield tones even more brilliant in color than those obtained 

 from the methods outlined above. Examples of these reducing agents are Adurol and 

 glycine. 



Adurol will produce tones which range from a rich brown-black to brilliant reds 

 when the dilution of the developer is very great; the exposure time has been increased 

 enough to compensate for this dilution, and increasing amounts of potassium bromide 

 have been added. The formulas on page 455 were developed by Ilford Limited of 

 London and published in their "Manual of Photography." The table of exposure 

 time, dilution, etc., has been changed slightly to meet the requirements of American 

 papers. 



These formulas used as mixed, without any dilution, will produce warm black- 

 toned prints. By diluting the solution, increasing the exposure, adding a certain 

 amount of a 10 per cent solution of potassium bromide, and prolonging the developing 

 time, we may change this tone from warm black to reddish brown. While different 



