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.
Depth Of Printing. Only practice and close observation can teach you this. With the combined bath, where both the toning and the fixing are done in one operation, the prints should be printed only a trifle darker than the tone you desire for the finished picture. Before removing prints from the frame, impress upon your memory the depth of each print, and if you find, after toning, that they are too dark or too light, govern yourself accordingly the next time you are printing. With a little practice you will be able to judge the proper depth.
Bath Too Warm. Allow your tray containing the toning and fixing bath to remain on the ice, or you can add a small piece of ice to the bath until it is of the proper temperature. If you have no ice, allow running water to flow into the outside tray. If this water is of the proper temperature the bath will soon become the same temperature.
Bath Too Cold. When the toning bath is too cold, remove it from the pan of ice until it assumes the proper temperature. At all times keep your thermometer in the toning bath and watch it closely.
Bath Tones Too Fast. This is generally caused by the bath having become too warm. It hastens the action of the chemicals and the print will tone before it is fixed. It is also apt to produce sulphurization, and although the prints may have a pleasing tone, they are not permanent and will fade in time. If more gold has been added to the bath than the formula calls for, it will tone too fast.
Bath Toning Too Slow. If the toning bath becomes too cold the action of the chemicals will be slow, and naturally it will tone slowly. It is advisable, however, to have the bath tone rather slow than too fast, because slow toning insures perfect fixing and the prints are more liable to be permanent.
Bleaching Of Prints In Toning Bath. Bleaching of prints generally occurs when a toning bath has been used too long, or when too many prints have been toned in it. The bath then becomes over-charged with silver from the prints and produces green tones, with the whites very badly bleached. Never tone more prints in a given amount of toning solution than called for in the instructions.
Bleaching Of Prints In After-Fixing Bath. If the prints have not been thoroughly washed to remove the toning solution, you are apt to carry some of the toning bath into the after-fixing bath; this would make of it a very weak toning bath and the prints, on account of the excess of hypo, would not only continue to tone, but would be apt to bleach.
Unable To Secure Blue-Black Tone. The combined bath is not adapted and is not intended for producing blue-black tones. If the negative from which you are printing is a strong negative, you can produce a purple tone, clear half-tones and highlights, and warm shadows, but the combined bath is only intended for warm tones.