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.
Overcoming Abrasion Marks. Frequently there will appear on the prints fine black lines or soiled whites, more especially on glossy prints. These are called abrasion marks and are caused by friction, breaks in the surface of the paper, or rubbing from the paper. As this causes the silver to rise to the surface, when it comes in contact with the developer black lines or soiled whites are produced. To overcome this difficulty add 5 grains of iodide of potassium crystals to every ounce of developer stock solution.
817. Such lines and marks can be removed from the print by rubbing with a small wad of absorbent cotton slightly moistened with wood alcohol. The prints, however, must be perfectly dry before cleaning.
818. For your future guidance results of first experiments should be preserved with a memorandum of your results noted on the backs thereof. These prints should then be filed in the regular proof file.
Practice Work. This instruction should not be undertaken until the previous instruction for general manipulation of Velox has been well mastered, because you must have a fair idea of the general results to be obtained with Velox before this special instruction is undertaken. As this instruction also deals with vignetting of prints, it will frequently be found most convenient to vignette some of the negatives, omitting objectionable portions, which, if left in the print, would tend to spoil the general effect.
820. After reading carefully, that this instruction may be thoroughly understood, make a few prints and observe their condition from the exposing, developing and fixing to the final drying. Note; we recommend full exposure with plenty of bromide. After a few experiments with the normal bath, as given in the formula, you should be prepared to adjust the developer for various effects, as explained in the instruction. Follow this with experiments on Royal Velox, which has a yellow body. It is intended for broad effects and is usually employed for large and sketchy work.
821. Preserve test prints of each manipulation, noting on the back of each all necessary data pertaining to their production. Include in this failures and successes alike, as both are important for your future guidance. Whenever meeting with failures, consult the difficulty department, where a remedy for the trouble will be found. File all prints in a proof file for future reference.
Note. - In professional studios, where a large number of prints are fixed, a fresh hypo bath should be made up each day. Hypo is very cheap, and more difficulty from discoloration, blisters, etc., can be traced to exhausted or incorrectly balanced hypo bath than from any other source. If a developer containing iodide of potassium is used the life of the hypo bath can be readily determined, for if the canary yellow of the prints does not disappear in five minutes, it is a question whether the hypo bath is in a condition to fix a print, no matter how long it remains in the bath.