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.
Developing Instantaneous Exposures With Ammonia Developer. The ammonia developer is not recommended for general work, nor even for special work, but is included in this instruction for the benefit of the few who wish to go to the extremes with experiments, for any reasonable and positive result can be obtained from any of the previous formulae given. There are extreme cases, however, where ammonia developer is an advantage, and to cover these cases is the object of this instruction. The amount of ammonia to be used in this developer depends to a large extent upon the exposure. Unless the proportions of the developer are prepared according to the exposure given the plate there is danger of fog. For extremely under-timed plates some like the ammonia developer, as more detail can be coaxed out with the ammonia as an accelerator than any of the sodas, and this formula is, therefore, supplied for these extreme cases only. We do not advise using the ammonia developing formula given in this instruction for regular exposures, or snap shot work made with the ordinary shutter, but for extremely short exposure, or those made with focal-plane or similar extremely rapid shutter giving less than 1/250 part of a second exposure in bright sunlight, and not more than 1/150 part of a second in dull light. This class of instruments are usually used on moving objects, such as running or jumping horses, cattle, birds and trains, or cars in motion, athletic sports, or any rapid moving object requiring most rapid exposure, and a quicker exposure than can be given with the ordinary shutter, for all such objects must be photographed without any blur, and to do so the shutter must move across the sensitized plate more quickly than the object being photographed. There are times also in slightly cloudy weather when one must make exposures of moving objects which could not be obtained at any other time. All such exposures if developed in the ordinary way would be considered under-timed, and even if they were treated as such (with the ordinary developing), if the exposure should be extremely short, one would not obtain as much detail and solidity as it is possible to obtain with the ammonia developer, providing the developer is properly balanced.
440. The alkalies used in ordinary developing are usually some soda of a strong, harsh nature. This strong alkali, if used on extreme under-timed plates, even with a very much diluted developer, has a tendency to choke and clog the highest lights, and the shadows being so very meagerly exposed the soda does not have the same action as it does on the more fully exposed parts. While the ammonia acts just the reverse, it is of a more penetrating nature, and has a tendency to attack the least exposed parts the most; therefore, the shadows being the the least exposed it attacks them first. In the developing of this class of exposure, we must assume that these plates are of short exposure, or extremely under-exposed, and while in previous instruction the treatment for the development of under-exposed plates has been pretty thoroughly covered, yet the former training dealt with general exposure of portraiture, interior, landscape and architectural photography. The formula in this instruction, however, is intended purely for the plates that are very much under-exposed, and for extremely rapid instantaneous photography. In such pictures the main object is to show the subject in motion, and to get the image perfectly sharp the exposure must necessarily be extremely short, and there must be enough detail and strength in the negative to supply the proper printing quality. In previous instruction on developing you have been advised as to the proper color of the negative, which should be a slight tinge of brown. In this case of extreme under-exposure, however, you will find that many times a very thin negative with a yellow color will produce prints of much finer quality than extremely thin plates of a brown color, such as is required for ordinary portraiture, architectural or landscape views, where the full exposure was given; for with the extremely thin plate the color of the plate slows the printing, and thereby adds strength to the shadows, thus supplying more brilliant prints.
441. In the early days of the dry plate, ammonia was universally used as an alkali in place of carbonate of soda, which is generally used to-day. The principal reason for discarding ammonia was, that the negatives generally obtained with this ammonia alkali were extremely yellow, and the latitude in development was limited, and if plates were carried a trifle too far in the developer the prints produced from them would be contrasty, with strong highlights, and hard shadows. Ammonia developer has its advantages, especially in the developing of instantaneous exposures, because its accelerator properties are much stronger, rendering the solution very alkaline, yet not harsh, and enhancing its deoxidizing power. It also possesses the advantage over all other alkalies of giving greater vigor; thus its action is quicker, and with the under-exposed plate very easily controlled, while for normal or full-timed exposure ammonia accelerator would be more difficult to control, and better results can be obtained with other accelerators.
442. The following formula will produce most excellent results, and can be altered, or the developer manipulated during development to suit most any rapid exposure: -
Bromide of Potassium..............
Ammonia ( specific gravity 800 )
It is necessary that the ammonia be concentrated ammonia , the ordinary commercial ammonia is too weak, and should not be used. If, however, the former cannot be obtained, and you are compelled to use the weaker ammonia, then you will need to use a larger quantity of it - sufficient to make up for the difference in strength.
443. As the ammonia evaporates rapidly the developer should not be made up until you are ready to use it. The proportions given in the formula above are just right for normal developer, and should be used without diluting unless the plate is extremely under-exposed, then you should double the quantity of water used, making twenty ounces in all.
444. With the ammonia developer on an under-exposed plate the image will appear a little quicker than with soda accelerators, but after the image is plainly visible the developing will be extremely slow, as the ammonia evaporates very rapidly and you will, therefore, from time to time need to add a few drops of ammonia, replenishing that which has evaporated. The very fact that the developer acts slowly will prevent the highlights from piling up and growing too strong before there is sufficient detail in the shadows, which would be the case if carbonate of soda were used.
445. The bromide of potassium provided for in the formula in excessive quantities, no doubt will seem strange to you, for in your past instruction you were told to use bromide of potassium as a restrainer for plates which were over-exposed. In this case, however, the bromide is used in excessive quantities to protect the plate from fog, as the ammonia is very apt to fog the shadows unless restrained with bromide. As ammonia has a tendency to attack the shadows, or the least exposed parts first, the bromide does not have the effect of restraining them, but merely holds them clear of fog, thus enabling the developing agent to act more freely.