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.
Washing Films. The hypo must be thoroughly removed from the film. There are several ways of doing this. Place the film in a wash-bowl of cold water and allow it to soak, for five minutes each, in five changes of cold water, moving it about occasionally to insure the water acting uniformly upon it. Or, give it a couple of changes as above, and then leave the film for an hour in a bowl set under a tap of running water.
207. With a bath tub and a piece of pine board available, the following is a very convenient way to wash film negatives: The board must be a little longer and a trifle wider than your strip of negatives. Pin the strip, back down (the back is the shiny side), upon the board, being careful not to touch the faces of the negatives with your fingers. Run cold water to a depth of six inches into the bath tub, and then float your board in the tub, film side down. The hypo, being heavier than the water, will go to the bottom of the tub, and in half an hour your films will be completely washed. The hypo cannot be removed from films by simply leaving these in a basin or tray of water. Hypo is heavier than water and sinks to the bottom, and the films, also, are heavier than water. Consequently, unless the water is continually changing, or is changed every few moments, the films are never actually out of the hypo solution, and cannot thus be expected to become free of the hypo. Only by generous washing in fresh water can the hypo be properly removed from films or plates.
Care Of Wet Films. Owing to their flexibility, films stand greater chances of becoming injured and the emulsion separated from the celluloid support than do glass plates. Therefore, it is necessary to handle the film, in all of the various solutions, with exceptional care and the temperature of all the baths should never be over 65° Fahr. Especially is this true in summer or in hot climates, when you should have your developing tray placed in another tray of water containing a small piece of ice, or running water.
Drying Films. When thoroughly washed, remove the surplus water from the film with a flat, soft rubber squeegee, a soft, damp cloth, or a damp ball of cotton, treating both sides of the film alike. To do this lay the film on a piece of glass or on oilcloth, and pass the squeegee or damp cloth over it, being careful that there is no grit on the squeegee or the cloth to scratch the film. Remove all the surplus moisture before hanging up to dry. If the moisture and tear drops are not removed they will cause transparent spots and streaks, which will show black in the print. Stretch a string across the corner of the room. Bend two pins like fish hooks. Push these through the corners of one end of the film to the heads, and hook one end of the film over the string; or, use the metal or wooden photo clips which can be bought at any dealer's. After the films are dry, keep them flat by placing them in a book.