This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Spots. Untoned spots are caused by not thoroughly and evenly immersing the print in the toning bath, or by air-bells forming on the surface of the print during toning. Air-bells may be avoided by toning prints face up. It is important to observe the directions in regard to fully and evenly developing prints. Prints that are over-exposed and not fully developed will be flat and of a yellowish color when toned.
Manipulating Carbon Black Paper. Carbon Black is the fastest chloride paper made, requiring handling in red or orange light to avoid fogging. It possesses remarkable latitude of exposure and will adapt itself to a wide range of negatives. It is at its best when used with the stronger grades of negatives. Carbon Black is made in five surfaces and two weights:
Glossy - Regular Weight - High gloss surface. Studio Special - Regular Weight - Smooth half-matte surface. Matte - Regular Weight - Slight grain with slight lustre. Dead Matte - Regular Weight - Smooth surface without lustre. Rough Matte - Double Weight - Broad rough grain with slight lustre.
Extra Heavy - Double Weight - Smooth half-matte surface.
Exposure. The speed of Carbon Black makes it possible to print it with an oil lamp, ordinary gas light, or incandescent electric light. The length of exposure of course will depend on the density of the negative, also the strength of the light used for printing. For the beginner a test should be made by covering some important part of the negative with a small strip of paper and exposing it to the light. When exposure is thought to be sufficient, remove the test strip and develop it. If the exposure is correct, the print will develop to the proper depth and stop.
Prints should be timed so that they develop to the proper depth without forcing the development. If prints stop developing before the desired depth is reached, it will indicate under-exposure. If development proceeds beyond the desired depth, it will indicate over-exposure.
986. Carbon Black developer should be mixed according to the following formula. Other developers may be used (See "General Information "), but we recommend the following as giving good color and gradation:
Sulphite of Soda (Dry).....................
Carbonate of Soda (Dry).........................
987. When ready to develop add one drop of a saturated solution of bromide of potash to each ounce of developer. Chemicals should be dissolved in the order given, thoroughly dissolving each before adding the next. If sodas in crystal form are used, double the amount given in the above formula. Carbon Black prints may be placed in water previous to development, but this is not necessary. Prints should be immersed quickly and evenly in the developer, removing air-bells that may form on the surface of the print by rubbing the surface with the tips of the fingers, or a tuft of cotton.
988. A properly exposed print will develop to the desired depth freely without forcing. The image will appear shortly after the print is immersed in the developer and development will proceed evenly and slowly enough to give full control during development. The speed of development depends on the temperature of the developer, the quality of chemicals used in the developer, etc. The best temperature at which to use developer is about 65 degrees Fahrenheit.
989. When a print is completely developed, it will apparently stop or pause in development. If a print is under-exposed, over-developed, or forced, it will be cold or blue in tone and lack richness in the shadows and detail in the highlights. Forcing the development is also apt to cause impure or fogged whites. If the print is over-exposed and under-developed, it will have reached the desired depth before development has stopped. An over-exposed and under-developed print will be inclined to be flat in general appearance.
990. Developer formula, as given, will prove satisfactory for all negatives. The contrast of Carbon Black paper can be controlled by varying the exposure. To obtain contrast from flat negatives, expose farther from the source of light, and do not over-expose. Soft prints from hard negatives may be obtained by exposing near the source of light and giving full exposure. After prints are developed, rinse in fresh water and transfer immediately to the fixing bath. Fix prints face up to avoid air-bells. For fixing bath and method of fixing see Paragraph 977-978.
991. After prints are fixed wash in the usual way in running water for about an hour. If difficulty arises, look under head of General Information for suggestions. For instructions in regard to mounting and drying see General Information, Chapter XXXVII (Artura Paper - General Information And Difficulties).