It seems that there is quite a lot of trouble caused by negatives turning too yellow or green. This can be caused by several things, and we will mention a few of them. If the sulphite used in the developer is not a good article, that will cause this trouble.
If it has been exposed to the action of the air, either in a dry state or in solution, that will cause it.
If you do not use enough sulphite in your developer that will cause it.
In reference to the foregoing it must be understood that the sulphite of soda controls the color or printing quality of the negative - the more you use the less of the yellow or green, and of course the less you use, the deeper the colors will be. It also follows that if the article be a poor one, it will not work with the strength desired, and as a consequence the yellow and green will be enhanced.
If you are anxious to see how your negative is progressing, and take it from the developer very frequently to watch development, and you should hold it in the air for very long at a time while examining it this will give you the yellow or green. The reason for this is: The developer on the negative has been oxidizing all the time you have been holding it in the air, and the result is a stained film. Therefore the plate should be examined as little as possible during the development.
It may be that you take the negative from the hypo bath and before washing it hold it up and examine it. If the hypo bath is at all charged with the developing agent this will cause yellow, for the reason that there is more or less of this agent in the film, and when you take time to examine the plate before rinsing, the agent is oxidizing, the same as during development, and the result is the yellow or green.
However, that which we consider the greatest cause of this trouble is the condition of the water in which the negatives are washed after fixing. The negative, when first taken from the fixing bath, may be just the color desired, but on taking the same negative from the wash water preparatory to drying it may be found a deep yellow. This is caused by the water in which it was washed. Some waters are heavily charged with chemical or vegetable matter, and this will affect the film of the plate unless it be hardened before putting into the wash water. If you will use one of the acid fixing baths as recommended by the various plate manufacturers you will not be troubled with this change of color.
It also happens sometimes that the negative will change color after it has been hung up to dry. This can be avoided by hardening the film with the acid fixing bath, as recommended above.
While we are not an advocate of the use of "bromide of potassium" on all occasions, and in reckless quantities, yet we consider a dark room without a bottle of it sitting "handy" just about on a par with a parlor without a carpet - it is not positively a necessity, but it makes a fellow more comfortable to have it. There are times in the lives of all operators when they find a negative that has a little more time than they can manage, without the use of this chemical, and like the Kentucky Colonel was about his pistol, "'Taint often I need her, but when I do, I need her d - m bad."
Don't use any smaller diaphragm for your lens than is absolutely necessary. It is a mistaken idea that many have that the "sharper" the picture the better. The most artistic pictures are made by having the "sharpest" point closest the camera, and as the eye travels backward over the subject, the focus should recede also. Never have the outline of a portrait perfectly sharp. This will cause that flat appearance, as though the subject were pasted against the background. The plan we have found most satisfactory is to focus on the lobe of the nose, then use a diaphragm just small enough to bring the eyes into sharp focus. This is of course referring to portraits. Groups will require a smaller diaphragm.
In mixing developers, bear in mind that:
Five ounces of dried carbonate (or sal) soda are equal to 12 ounces of carbonate soda crystals.
Six ounces of carbonate of potassium is equal to 12 ounces of carbonate of soda. One ounce of dried or granular sulphite of soda is equal to two ounces of sulphite soda crystals.
Some claim it is beneficial to have some old developer in connection with the new, while others prefer a fresh solution altogether, personally we prefer a fresh solution, for there is no developer that has been used three or four times, or even once, that is so pure, chemically, as one that has never been used. And it seems that most of the dark room men who prefer the use of part old and part new claim that it gives them better control of the negative in development. If this be the only reason for preferring it, it would seem the better plan to time the exposure correctly, and use a new developer which we know to be chemically pure.
Relative to the above, don't condemn a plate, when you are using the formula of developer, that was intended for another brand of plates. "Render unto Caesar that which is Caesar's." If you are using a certain brand of plates, use the formula for that brand of plate. It may be necessary, however, to change the proportions of the various ingredients in certain localities, as mentioned above, but stick to the general formula.
It is sometimes the case that we have a negative to develop that has been lighted in Rembrandt lighting and the subject has on dark or black drapery. In this lighting it is more difficult to get dark drapery than white. Now when the image begins to appear it will be noticed that the draperies lack the proper amount of detail in the deepest shadows. If a camel hair brush is dipped in a weak solution of the alkali that is being used in the developer, and run around over the shadows, it will at once be seen that the detail comes up better. The developer should be thrown into one end of the tray during the operation, but should be flowed back over the plate after running over it with the brush. This will prevent fog from an excess of alkali.
It is peculiar the slight regard some operators have for the suggestion made by all plate manufacturers "that plates before exposure should be kept in a dry place." We have all read this warning hundreds of times, and yet numbers paid no attention to it. This is one of the most important points connected with negative making. The reason of its importance is that, a plate is much more sensitive when in a thoroughly dry condition than if damp. Therefore considering the fact that the emulsion of the plate will absorb atmosphere just the same as a sponge absorbs water, we can easily understand that our plates, to give entire satisfaction in point of speed must be kept in a dry place. It therefore follows that plates will be more speedy in cool dry climates than in damp hot climates unless some precaution be taken to counteract the effect of the climate. These precautions will best be suggested by the photographer living in those sections.
Don't think because some good dark room man gave you what he calls a crack formula for developing plates that you can in all cases use the same formula. This you may do, and again you may not. The conditions under which your friend labors may be entirely different from what you have to contend with. The water he is using may be purer than that which you use. The water you use for washing the negatives may be charged with vegetable matter, and your plate may turn yellow after development. The best plan is to use melted ice water for mixing the formulas, and then the conditions will be more equal. But the style light you are working under will step in and play an important part. Your friend may have a light that is inclined to contrasty effects while your light may have a tendency to flatness. If this be the case, it can not be possible that both should have exactly the same formula, without "doctoring" it, for these conditions. "Know thy light, and developer."
Nearly all photographers have at times wished they could get a proof of a negative when it was first made. Since the advent of Velox paper this is easily done. After the negative has been developed, and fixed, rinse it well under the tap. Now take a sheet of Velox paper and immerse it in a pail of water until thoroughly limp, then place it on the wet negative, press all the air out from under it and then expose to the light. After the required exposure has been given remove the print from the negative and develop as usual. Be sure to wipe the drops of water from the back of the plate before exposure, as they will show in the proof. It will take about twice as much exposure on a wet negative as it would on the same negative were it dry.