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.
Edges Of Print Cracking. This is due to the prints curling because they were not perfectly flattened in the first wash water. Be careful that you do not use more water than is absolutely necessary to cover the prints in the first washing. Flatten the prints to the bottom of the tray. Set the tray on end, allowing it to stand for five minutes, when the prints will be perfectly flat and will not break in future handling. Extreme cold water will cause prints to curl even after flattening, and constant handling when in this condition will induce cracking. Always keep the temperature of all baths and wash waters uniform.
Paper Sticking To Negatives. If the paper is damp the tendency is for it to stick to the negative when printing. In some cases, where the paper is extremely fresh, it will adhere to the negatives; or if the negatives are extremely hard and contrasty, and are printed in hot sun, the paper will stick. If any of these difficulties are met with, brush the negative with French chalk before printing. Never blow the chalk from a plate, for if any saliva touches the gelatin surface it will cause the paper to stick fast.
White Spots. These are generally caused by insufficient handling in the hypo bath, or by not thoroughly washing after fixing. The prints must be handled over in the final wash waters and not allowed to mat together.
136. White spots are also caused when the prints dry very slowly, or when placed upon poor quality of blotters or paper when drying. If there is any undissolved hypo in the fixing bath and the crystals come in contact with the surface of the print, small white or yellow spots will result.
Red Spots. The most common causes of red spots are unclean trays, finger marks, air-bells, and insufficient preliminary washing. If from finger marks, they will be easily recognized by the grain of the fingers. If the spots are uneven and scattered over the paper, or if the prints have the appearance of being greasy when they are in the wash water, the difficulty comes from oil or grease either on the hands, trays or in the water. This trouble may be readily overcome by adding to the second preliminary wash water 1 ounce of saturated solution of carbonate of soda to each gallon of water. The prints should be handled over in this water for 5 minutes. The alkali will cut off all grease or oil, and also neutralize the acid preservative chemicals in the paper. The remaining preliminary changes of water will wash out all trace of this alkali, the prints then being in a neutral condition when entering the gold bath.