We wish it understood that we are not advertising any particular brand of plates, but what we shall do is to try and give you an insight into the developing and manipulation of all brands of plates, as far as it lies in our power. It will be for you to choose the brand of plates you think will be best suited to your use. Your light will to some extent govern this. If your light is high and narrow and steep, you will require a faster plate than you will for a low light. The reason is that a high, steep light has a tendency to give contrast, hence you will find a fast plate will yield a negative full of roundness and detail. On the other hand, should your light be low, wide and flat, you will find a slower plate advantageous, for the reason that such a light will give you negatives bordering on flatness. The reason the slower plate is better here is that it will give more contrast. The high lights will be stronger and the shadows clearer, thus giving more brilliant results.
The emulsion of every plate is different from every other plate, and yet there is such a striking similarity that we may speak in general terms on the developing of all plates. Certain chemicals have the same action on all plates, but the formulas for the manipulation of all plates are different.
One brand will receive a stronger alkali, while another will require more of the developing agent. It is our intention to speak particularly of the action of what is known as the pyrogallic acid developer, but as we go on, we will make a few remarks on what are known as the coal-tar developers. First we will give you an idea about how the plate is coated, so that you can more readily understand the action of each chemical on the emulsion. The emulsion is deposited on the plate in what we may term little globules or sacks. Now these little sacks differ in size on the different brands of plates. In some plates the sacks lie very close together, forming what we call a very fine grain negative. As to the various brands of developers on the market, we would say any of them will give you good negatives, but some of them will give you better printing quality in the negatives than others. Should you use what is known as metol, you will get a negative full of detail and roundness. This negative will give good results on glossy paper, but not so crisp a print on the matt paper. Again we have what is known as the hydro-quinone developer. The action of this developer is just the reverse of that of metol.
It will give you a strong negative, the gradations from light to shadows of which do not tone down as evenly as they do by the use of metol. Yet it is especially good for process work or etching. Then we have eikonogen, rodinal, metacarbol and numerous other brands of developers, all of which are good, but lacking to some extent in the printing qualities which we secure by the use of pyro-gallic acid. By the use of any of these developers you get a negative of a blue or black color, and the resulting print from this negative will be gray in the high lights, owing to the fact of there not being enough color in the negative to hold back the whites under the printing light. The action of these developers when first flowed over the plate is much quicker than that of pyro. In fact, the image will appear almost immediately. But we must carry the developing much farther when using any of these than we would for pyro, owing to the absence of any color in the negative. By the use of any of these developers we have what we may call two stages of development, and to secure the best results, we must go into the second stage of development, or until we secure a body development, which means that the image has gone down into the emulsion and does not rest on the surface. What we wish in a negative is good strength, crispness and yet plenty of detail and a good, warm tone that will yield a good print.
The color liked best in a negative is what we may call an amber. We want just enough of the yellow in it to give snap to the print. While the tar products will give a more pleasing effect to the negative, we must remember it is not the negative that we sell, but the print. Therefore, we should make the negative simply a means to an end, and work for the best printer. In the directions for working any of the plates, you will find a formula for making pyro developer, and in most cases this seems to be the favorite developer, judging from the fact that it is usually the first formula given. We will, however, give you the formula which we claim as our favorite, and which we have found to give the best printing qualities of any we have tried.
Stock Solution No. 1. - Carbonate of potassium, hydrometer test 40 degrees.
Stock Solution No. 2. - Sulphite of soda, hydrometer test 70 degrees.
Stock Solution No. 3. - "Water, 24 ounces, in which you have dissolved 15 grains of oxalic acid, after which add 1 ounce of pyrogallic acid.
We call your attention to the fact that I have given you the carbonate and sulphite solutions separately. The reason I do this is because the carbonate is an accelerator, and the sulphite is to some extent a retarder; therefore, if we had the two together, as some formulas recommend, and should wish to hasten development by the addition of carbonate, we would at the same time retard the development by adding sulphite.
By having the two together, we have two forces working in opposite directions. We spoke of the emulsion being deposited on the plate in little sacks. Now, the alkali solution or stock solution No. 1 which is, in this case, carbonate of potassium, is to open up these little sacks and allow the pyro or stock solution No. 3 to deposit on that portion of the plate which has been acted upon by the light, and this is done in what we call gradations, giving us high light, half tones and shadows. The oxalic acid in solution No. 3 has no action upon the plate at all. The sulphite of soda, solution No. 2 controls the color of your negative, or the printing quality. Should we leave out the sulphite, we would have a negative of a deep yellow color, which would be just as objectionable as one of blue or black. Solution No. 1 is, as we have said, an accelerator, therefore, should we have a negative slightly undertimed by the addition of carbonate of potassium or whatever alkali we are using, we may improve the negative. On the other hand, the pyro is what we will call the blackening agent.
Therefore, should we have a negative that is overtimed, by the addition of pyro, we will secure more contrast, and thus save the negative. It would doubtless seem peculiar to you when we tell you that for an overtimed negative you require a stronger developer than for one that is undertimed. Yet, it is nevertheless true. When we say stronger developer, we mean strong in pyro, for it is this that gives contrast, and that is what we must work for in an overtimed negative. I have found it a good plan to let your tray rest without rocking in case you have a negative just a trifle overtimed. This will give more contrast. The reason is that the developer on the plate is not changing, and is oxidizing all the time and becoming old, and you will find the older your developer, the stronger contrast you will get. If you should have a negative of a person with a very hollow cheek, a good way to save retouching on this negative is to have at hand what is known as a druggist's dropper, and fill it. with a weak solution of the carbonate, and allow a drop at a time to fall directly in the hollow of the cheek, rocking the tray after each drop to prevent fog from an excess of alkali. The action of the carbonate is to open up the pores or sacks of film and allow the pyro to deposit more freely, thus rounding out the cheek better. Another good thing is to have a pipe-stem and blow the warm breath through it into the hollow of the cheek. This, too, will hasten development locally. To get what we call an amber negative, we must have our stock solutions mixed as given, and we must also mix our developer for use in the following manner: Take an ounce of each Nos. 1, 2 and 3 stock solutions to eight ounces of water. This is a normal developer, to be used for a normally timid negative. If we know our negative to be overtimed, we might add two or three drops of a 10 per cent solution of bromide of potassium. With a normal timed negative and normal developer, the high lights should show in about twenty seconds after the plate is flowed. If it does not, add a few drops more of the alkali or carbonate, for it is undertimed. If it shows sooner, add a few drops more of the pyro, or bromide of potassium, for it is overtimed.
After it is developed, rinse thoroughly and place in an alum bath composed of water, 10 ounces; alum, 1 ounce. Leave in the alum bath two or three minutes, after which rinse again and place in plain hypo bath to test 85 degrees hydrometer test. After your plate is fixed, take it from the hypo bath and put it into the alum bath again without taking time to rinse it. The reason for this is, that the air will turn the negative too deep a yellow. When you take it from the fixing bath there is more or less pyro remaining in the film, and, by exposure to the air, it becomes oxidized and this turns the film yellow. Poor grade of sulphite, or too little of it in the developer will cause yellow negatives. By exposure to air the sulphite deteriorates, becoming a sulphate and is useless in negative making. Therefore, you should keep the solution tightly corked. The pyro solution should also be kept corked, as it will oxidize and turn yellow, becoming worthless. It is sometimes the case that we are troubled with foggy negatives. There are a number of things that will give us this trouble - light entering camera, plate holder, dark room or too strong developing light, or dust on the lens, and too strong alkali in the developer will cause it. Your developing light should be made of a ruby glass and one thickness of postofrke paper, but before using it test it by exposing half a plate to it at a distance of one foot for three minutes, after which develop in total darkness. If there is no difference in the exposed and the unexposed end of the plate, your light is safe.