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.
Keeping The Trays Clean. Chemically unclean trays are the cause of a great deal of trouble to photographers. It is essential that each tray be kept for one particular purpose and used for that specific purpose only. It will pay a hundred times over to have a special tray for each part of the manipulation. For wash waters and hypo baths, wooden trays lined with oilcloth, or rubber cloth, are perfectly safe and can be constructed cheaply. Have plenty of them. In good plain letters mark one " First Washing," one " Gold Bath," one " Between Baths " (for washing between gold and platinum baths), one for " Hypo Bath " and one "After Hypo" (to be used after prints come from the hypo). The toning trays should be made of chemical-proof material, such as porcelain, or hard rubber. The number of trays before mentioned may at first seem unnecessary, but it is always best to be on the safe side, and as trays are inexpensive, it is advisable to have plenty of them, and each for a particular part of the manipulation. It will pay well in the end.
Dusting Negatives. No difficulty will be experienced in keeping the negatives perfectly free from dust if the printing room, including work table and a shelf or other support used for printing, also the printing frames, are kept clean. It is extremely important that the printing room be kept as free from dust as possible. Carefully brush both frame and negative before placing the paper on the negative. This saves time in spotting prints.
Judging Correct Depth In Printing. Difficulty will at first be experienced in securing the proper depth of printing, but if you bear in mind that it is necessary to make allowance in the printing for a certain amount of bleaching or eating away of the highlights, and print accordingly, no trouble will be experienced. The prints should be carefully examined and their appearance particularly noted before placing them in the first wash water. Notice carefully the changes as they take place in the toning baths, and fixing bath, then examine the prints carefully when dry. If they are too dark or too light, variations in the next printing should be made accordingly. The printer who is able to print an entire order with little or no variation in the depth of printing, has mastered the secret of this branch of work. It is practice and only practice that will enable you to overcome this difficulty.
Paper Sticking To Negatives. Sometimes when negatives go to the printer to be proofed, they are damp and the paper sticks in places. In such a case the paper must be removed from the negative at once or it will leave stains. Remove the paper by rubbing lightly with a tuft of cotton moistened with alcohol. If the stains show, fix the negative again in a hypo bath. Another way to remove the bits of paper is by rubbing with the end of a match dipped in alcohol.
256. This trouble is also caused by the paper sweating and sticking to the film, and can be overcome by using a felt pad back of the paper in printing frame. A better scheme is to flow the negatives with negative varnish.
257. Dusting negatives with pulverized soapstone and brushing off will prevent sticking.
258. This trouble of paper sticking is liable to happen in the spring or fall, or when there is a long season of damp weather. The paper, negatives and pads in frames become moist, causing the trouble.