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.
Introduction. Developing paper, more commonly called gaslight paper, is a paper which can be printed by light of any kind and from negatives of all descriptions. The image is not visible after exposure to the printing light, being seen only after the developer is applied. The most marked difference between this class of printing papers and printing-out papers is in sensitiveness. So sensitive is the gaslight paper that it cannot be handled safely in daylight, nor should it be unduly exposed even in ordinary lamp light. The entire process of manipulating developing papers is quite simple, but like all other photographic processes it requires some skill and judgment, both of which are readily acquired by careful observation of each detail and by close adherence to the rules given herein.
642. The developing paper process is one of the most convenient methods of finishing prints. Pictures may be produced with it regardless of weather conditions. Neither cloudiness, dampness, or any other deterring feature need be considered. The photographic worker is entirely independent in this respect, being able to finish prints either day or night. For the professional photographer this process simplifies work enormously, as the printer is able to take one negative at a time and print the complete order. This makes it possible to give precedence to rush orders and make complete delivery of the order when promised.
Further than this, each and every order can be completed and ready for delivery without delay.
643. It is not necessary for the amateur to go into a closed dark room, as it is possible to print work at night, which may be done on kitchen or dining-room table, in comfort. An ordinary electric, gas, or lamp light, can be used for printing. After printing, the paper may be developed but a few feet from the light, by simply interposing between the light and developing trays a piece of heavy cardboard, or similar material.
644. In no other department has the photographer such a range of choice as with developing papers. They are made in many different grades and surfaces, which make it possible to obtain good prints from practically any kind of a negative, by using proper judgment in the selection of the particular paper best suited to the negative in question.
Brands Of Paper. So rapidly has the popularity of this process developed, that there are now on the market a great variety of brands of developing papers. Among the most popular are "Velox," "Argo," Artura" and "Cyko," each particular brand having its various grades and surfaces. Every brand of paper has its own peculiar qualities, yet the particular brand for your use is not of serious importance. However, the grade and surface must be taken into consideration when making the first experiment.
Grades Of Paper. Most of the gaslight papers tend to increase contrast, being especially suitable for thin, flat negatives. Practically all developing papers are divided into two general classes - hard and soft. The hard grade is intended for flat negatives, as it works with a great amount of contrast. It should not be used with hard, contrasty negatives.
647. The soft grade is best suited to negatives of strong contrast, giving the best results when soft effects are desired.
648. All manufacturers do not use the terms "hard" and "soft," but the hard grade is generally termed "Regular," or "Carbon," while the soft is "Special," or "Portrait."
Choice Of Paper. The majority of persons being initiated into the art of photography as a rule lean toward the selection of glossy surface paper. Only after the artistic taste has been cultivated does the inevitable revolution against the glossy surface set in. We do not question the fact that glossy prints on printing-out paper give most pleasing results, on account of warm tone, but it must be admitted that with developing papers it is different - the black and white image appearing much more rich on a matte surface. Not only is this true, but the glossy gaslight papers are not as easy to manipulate. At times they have an objectionable tendency to yield surface marks, which afterward have to be removed. On the other hand, the very rough papers require special care, and should not be used when making first trials. The best grades and surfaces to employ are those which have a tendency to increase the contrast, and at the same time give a smooth matte surface. Therefore, the first work should be made on a paper like "Velox" Regular Carbon, "Argo" Carbon Matte, "Cyko" Contrast Matte, "Artura" Carbon Black Matte.
Caution. It is necessary to caution the beginner at the very outset of his work not to be discouraged by apparent failure in early stages of the work. Study this instruction not only once, but go through it thoroughly two or three times, as the cause for any failure will probably be that some point which is essential to complete success has been overlooked.