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.
Negatives Full Of Detail, But Very Thin. The plates were either over-exposed or under-developed, or both. It is advisable to carry plates which appear flat and are overexposed, farther in the developing. If they are then too dense reduce them according to instructions given in Reducing. With a bath in good condition, and the proper time given for development, you should obtain good negatives. Be sure you make no mistake in the time.
Negatives Too Yellow When Developed In The Pyro Developer. When this occurs it signifies that the sulphite is not strong enough, or the sulphite solution is old, and has deteriorated. We would advise that you prepare a new stock solution of sulphite, being careful that it is made the proper strength. The color of the plate is controlled entirely by the strength of the sulphite. It requires a certain amount of sulphite to give you the right color, and to balance the developer.
Note. - If crystal sodas are used in place of anhydrous you will require twice the amount.
Negatives Too Blue. As the sulphite controls the color of the negative, blue or gray negatives would signify that the sulphite stock solution is too strong. Carefully test it, and if too strong dilute with water, and try it again, until the desired result in proper color is obtained. Your carbonate may also be weak or impure, but if the negative is right in every other respect but color, then your sulphite alone is at fault.
When Developing With Pyro Plates Develop To A Certain Stage And Then Stop. This will only occur when the developer is too weak or is over - worked, and the developing agent has become exhausted. Pyro in solution deteriorates quite rapidly; therefore it is liable to work slow after a few hours' use, especially in warm weather or hot climates. Do not over-work the bath in a warm climate. Not more than twenty-four to thirty 5 x 7 plates should be developed in a one hundred ounce bath. After developing this number of plates the bath better be discarded.
Plates Developing Contrasty In Hydro-Metol Developer After The Bath Has Been Used For Some Time. This is caused by the bromide which was released from the plates previously developed, and which, when dissolving, became a part of the developer, thereby restraining the development. A bath in this condition is unreliable and a new one should be prepared.
Top Edges Of Plates Not Developed. This will occur if there is not sufficient developer in the tank to completely cover the plate.
Some Plates Develop Quicker Than Others.
This will occur when the exposures vary. Carefully examine plates just before placing in hypo. Those that are not fully developed return to the developing tank, and prolong the development. Ordinarily a slightly under-exposed plate and a normal exposed one will be completely developed at the same time, but invariably an over-exposure will require a little longer developing, and possibly reducing afterwards.
Scum Gathering On The Developer While In The Tank. This is apt to happen if the tank is left uncovered for a considerable length of time, and is caused by oxidization. This scum will do no harm if the bath is stirred up, and if the plates are raised and lowered two or three times when placed in the developer. Should you fail to do this the scum will settle on the plate and cause transparent spots, stains and uneven development. The safest way is to keep the tank covered always, and when sediment or scum collects filter before using.
Sediment Gathering In The Developing Tank And Bottle Which Contains Hydro-Metol Developer. This is a precipitation which will occur, but will do no harm and have no injurious effect in the development.
Testing Development For Temperature. This is a very simple matter. Provide yourself with an all glass dairy or bath thermometer, which can be purchased very cheaply. After you have diluted the developer place the thermometer in it. If too cold, add a little hot water. The extra water will make very little difference in diluting the developer. If too warm, add a small piece of ice or a few ounces of very cold water until you have produced the correct temperature; or place the tank in a tray of ice water.