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.
Washing. One hour's washing in running water is sufficient. After washing the plates may be placed in the drying rack in the usual way. Where plates are developed, fixed and washed back to back in the developing tank, they should be separated and the back thoroughly rinsed before placing in the rack to dry.
The developing tank should be scrupulously clean at the time of developing.
A thermometer should always be used in testing the temperature; 5° difference in temperature will make a difference in the required time of development.
Do not leave the solution standing in the tank when not in use.
Do not leave exposed plates in a damp tank for any length of time before development.
Should negatives appear dense you will understand that they are over-developed. Should they appear thin you will understand they are under-developed.