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.
Fixing Bath. After a print is developed it is only partly completed, for it is yet sensitive to light. All sensitive salts that have not been affected by either light or developer must be removed before allowing a strong light to fall on the print. This is accomplished by immersing the print in another solution, termed the fixing bath. The fixing bath used for gaslight papers is different from the ordinary fixing bath. The ordinary plain fixing bath is composed of four parts of pure water and one part of hypo. This plain fixing bath is used for fixing dry plates or films and also in a diluted form for fixing printing-out papers, but as gaslight papers are coated with a gelatin emulsion, and the chemicals used for developing are strongly alkaline, the print, when developed, is very soft. There would be danger of stain and discoloration unless it were treated in a hardening bath; therefore do not use plain fixing bath, but an "acid fixing bath," which will harden the emulsion and clear the print as well. The acid hypo can be obtained from any dealer. It is put up in wooden or pasteboard boxes, and to be ready for use only requires dissolving in water, according to the given directions.
Printing. In addition to the trays and solutions for developing, it is necessary to have a printing frame the size of the largest plate or film from which you are to print. By fitting a piece of clean, clear glass in the printing frame any smaller size negative can be printed from equally as well as if the actual size frame were used.
439. To begin with, two dozen sheets of what is known as the regular grade of paper should be sufficient. But as gaslight paper, if kept in a dry place, will last for months, it would be economy to keep a supply of a few dozen or one-half gross on hand. For the information of those without experience in the manipulation of developing papers, we would say that the image is not visible on the paper while printing, but appears only when it is placed in the developing solution.
440. As stated in a former paragraph, the different manufacturers make many grades of papers, yet for the beginner we would advise the use of the "regular" grades only. In subsequent instructions you will be taught how and when to use the different "special" grades. The regular carbon grade papers are intended for thin negatives, and as most beginners' negatives are thin, better general results will be obtained with this paper.
441. Printing and Developing Outfit.
While it is possible to get along very nicely with but two trays, one for developing and the other for fixing, provided an ordinary clean wash bowl can be used for final washing, yet, as the majority of failures are due to the careless handling of the prints, we recommend the following:
1 5x8 tray, to be used for developing only.
1 5x8 tray, to be used for fixing bath only.
1 5x8 tray, to be used for intermediate washing.
1 5x8 tray, to be used for final washing.
1 printing frame, size of largest plate used.
1 package of printing paper.
1 8-ounce glass graduate.
1 glass stirring rod.
1 package or tube of developing powder.
Developing or "Gaslight" Papers - Regular Grades. 239
1 package of "acid hypo."
1 ounce of bromide of potassium.
1 dozen sheets non-linting blotting paper.
442. The above outfit is for printing and finishing 4x5 or 5x7 prints. If larger prints are to be made, the trays should be in proportion. Again, we would caution you to use the respective trays only for the purpose intended, viz., developer tray for developing, hypo tray for fixing, and water tray for washing. Label each tray so that there will be no danger of mistake, for should the hypo tray be used for developing, even after very careful washing, a slight trace of the fixing salt may ruin the developer and cause the prints to be spotted. It is, therefore, very important that each tray be used for one purpose only.