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.
Practice Work. The making of Velox prints is most successfully done by artificial light and we advise its use, especially for your first experiments, and as the general run of negatives is more suited to the special grades, we advise using these grades for your first work. You may employ any surface to your liking, whether smooth, matte or rough. The principal difficulty with the manipulation of Velox and other gaslight papers lies in the proper exposure. The one advantage of artificial light, be it gas, electric or even the light from a kerosene lamp, is that the strength of the illumination is always the same and when you once obtain the proper exposure, all future exposures from the same or similar strength negatives can be made exactly alike. For your first experiments in developing Velox we advise using the formula exactly as given herein, for this formula is prepared for normal exposures and really needs no altering. After you have had a little experience, the formula may be altered. Altering is advised in order that you may learn the effects produced by diluting as well as using full strength. You will learn by careful reading of the instructions that to produce soft prints, the developer must be used full strength while if you require more contrast dilute the developer with water.
Note. You will observe that this method of obtaining contrast with Velox prints is just the opposite to obtaining contrast when developing plates; because when developing plates, by adding more water you produce softness and more detail, while with Velox the reverse is the case. The addition of water, or dilution in other words, gives contrast. Remember this. For your first experiments you should make up several prints on Special Velox, observing the exposure necessary to the final development and fixing. Note on the back of each print all data connected with the production of the results. Should the first prints be failures, so much the better, as in that event they will prove the most important prints in your collection for future reference.
726. When failures are encountered consult the Difficulty Department, where you will find the cause, remedy and prevention for all troubles related to the difficulty in question. After you become familiar with Special Velox, take up the other grades and surfaces and manipulate them, following instructions closely. In all cases make note on the back of all your test prints, whether good or bad, and file them in your proof file. They will serve as good references for future guidance.