THE DEVELOPMENT OF THE PLATE.
IT has been truly said by no less an authority than Captain Abney, whose works upon photography should be studied by all who wish to excel, that the development of the photographic image is both an art and a science; and probably few experienced photographers will take excep tion to the statement.
Development., of course, can only be carried out in the non-actinic light of the dark-room, for although the plate has been exposed to light in the camera, and has received therein the image cast upon it by the lens, it is still as sensitive to white light as before, and the slightest exposure to such would totally obliterate the image. This being so, we may take the slides to the dark-room and make the necessary preparations for developing our first negative. We commence by mixing our developer, and, to prepare a " normal" solution, that is to say one of medium strength, neither weak nor strong, which should serve, if we have correctly timed our exposure, to develop a good negative, we proceed as follows. Into one of the 4 oz. measures we pour 3 oz. of clean water, then with the minim graduate we add, in the following order, 60 minims of the "pyro." solution, 40 minims of the " bromide," or " restraining,"_ solution, and 30 minims of the " ammonia," or " accelera ting," solution—stirring the mixture well with a clean glass rocl.
All white light must now be excluded from the room by putting the non-actinic screen in position at the window. 'Ile plate which we first exposed should then be removed from the dark slide, and, after its surface has been lightly brushed with the broad carael-hair brush, laid, with its sensitive surface upwards, in the ebonite tray which we have reserved for developing negatives. Dust is one of the photographer's greatest enemies, and the object of dusting the plate, both before and after exposure, is to remove any small particles which, notwithstanding all precautions, will find their way on to the plate. The developer is now poured, with a gentle sweep, over the plate, in such a manner 'as to cover its entire surface with one flow of the solution; the operation requires a little knack to perform it successfully, but it i,s easily acquired. It is for this reason that we have mixed up rather a generous amount of solution, and when the reader gains a little experience he will find that 2 oz. of solution will suffice for developing a half-plate. If the solution does not entirely cover the plate, or only does so in patches, the negative will probably exhibit " developer markings," which may show in tho print. It is well, in commencing development, not to allow too much light to fall upon the plate ; therefore the dish containing it should be removed to the table, which we have assumed to be on the left of the sink. It is better not to allow the solution to remain stationary, but to rock the dish with a slight oscillating motion, which will cause the developer to flow in even waves to and fro over the plate, and will ensure uniform development and an immunity from stains. The development of the "latent image " is one of the most beautiful experiments which modern science has revealed, and one which cannot fail to fascinate those who witness the process for the first time. If, after the solution has been allowed to remain upon the plate for about two nainutes, we perceive no indication of a change in its appearance, we may conclude that the plate has been somewhat under-exposed, and, to remedy this, we measure out another 20 minims of the ammonia solution, pour it into the 4 oz. measure, pour the developer back from the tray on to the fresh solution, and, after a stir with the glass rod, again pour it over the plate. The object of making the addition in this way is to thoroughly mix the solution, for if it were imperfectly mixed, unequal develop ment, or stains, would result, and the negative would con sequently be spoiled. The plate must now be carefully watched. Probably after the strengthened solution has been acting upon it for about 30 seconds or so a portion of the plate will begin to darken—the part represented by the sky; this will be followed by the walls and roof of the house; the fence and objects in the foreground will also become visible. At this stage we may remove the plate from the developer, and, after giving it a slight rinse under the tap, to avoid the formation of stains, we proceed to examine it more closely by holding it up to the orange light of the non-actinic screen, not, however, for too long, for undue exposure, even now, might cause a slight veiling or fog. Our hasty scrutiny will show us more distinctly the detail in our negative, but we shall probably notice that although it appeared very black and dense when in the dish, even the darkest portions seem thin when viewed by transmitted light. This proves to us that development has not been carried to a sufficient extent, and if we were to arrest the process here, we should find, when the subsequent necessary operations had been completed, that we had a mere ghost of an image which, for practical purposes, would be value less. When judging the" density," as it is called technically, of the developed image, we must remember that the negative will always appear to be denser before the next operation of fixing than it is in reality, therefore an allowance must be made for this fact. We, therefore, return the plate to the tray, and having added another ten minims of ammonia solution as before, again pour the developer over it, con tinuing the rocking motion as before. The appearance of the plate will now quickly alter, further detail will appear, and the image will gain rapidly in vigour, until a point is reached when nearly the whole surface of the plate will appear obscured. The plate should then be again removed from the tray, and after a rinse under the tap, submitted to a second examination by transmitted light. It will now
be observed that the image has considerably gained in density, and if the highest lights, that is to say, the blackest portions of the negative, appear nearly opaque, it may be assumed that the plate has been sufficiently developed, and after a good wash under the tap it may be placed in a clean porcelain dish, in which some of the alum clearing bath has been poured, and allowed to remain therein for five minutes, while we are preparing the fixing bath. Into the dish which we reserved for this special purpose, we pour 4 oz. of the saturated solution of adding to it 9 oz. of water, and well stirring. In all our dealings with this chemical we must take great care not to contaminate either dishes or measures with it, and if any of the solution should be spilled upon the table, it should be immediately wiped up with a cloth. The negative may now be removed from the alum bath, and after another thorough wash under the tap, should be placed in the fixing-bath. Up to this point all the operations have been conducted in the non-actinic light; but when we have safely placed the plate in the fixing solution, we may remove the non-actinic screen, as white light at this stage will not further affect it. The object of the fixing-bath is to dissolve out of the film all the sensitive silver salt which has not been acted upon by light. It will be instructive to watch the change which the plate will undergo after being placed in the fixing solution. The back of the plate will rapidly lose the creamy appearance which it previously exhibited, and the unreduced silver will be quickly dissolved by the solution. After the plate has been allowed to remain in the fixing-bath for about ten minutes it should be removed, when the back of the plate should have quite lost its white creamy appearance ; if, however, some patches of white still remain, the plate must be returned to the solution until all such signs disappear. A quarter of an hour in the fixing-bath is a safe time to allow. The plate should then be most thoroughly washed to remove all traces of the fixing solution, for if any hypo. be left in the film it will in time cause the negative to become discoloured, if not to entirely fade. The negative should, therefore, be held by its edges under the tap, and the water allowed to run gently over it for about a couple of minutes, after which time it may be placed in the grooved rack of the washing trough, which should then be placed under the tap, and a gentle stream of water allowed to run through it. About two hours of this washing will be found sufficient for all practical purposes. Although in the course of the foregoing operations it will be impossible to avoid handling the negative to some extent, the tyro should understand the right way in which to do it. The plate whilst wet must never be held between the thumb and fingers, as an indelible impression of them in the gelatinous film would result, which would, of course, be duly recorded iu each print made from the negative. When it becomes necessary to examine the plate during development, it should be raised from the bottom of the dish by cautiously slipping the nail of the forefinger underneath it, when, its edges being held between the forefinger and thumb of the other hand, it may be readily lifted from the solution. Even this, however, should not be clone more frequently than necessary, as the heat of the hands, more particularly in hot weather, slightly warms the gelatine, and causes the film to partially detach itself from the glass—this defect is known as " frilling." Let us now remove our negative from the washing tank, and hold it up to the light with a view to ascertaining its quality. Now, it is wellnigh impossible to describe the appearance of a properly exposed and developed negative in language which can be appreciated by the beginner, and I much wonder that plate makers, or dealers in photographic apparatus, have not conceived the idea of selling sets of negatives showing the result of over, under, and correct exposure. Such assistance would be of immense educational value to beginners, and I throw out the suggestion in the hope that some one may think it worth acting upon. Upon examining* our negative, we shall, in all probability, find that it is somewhat under-exposed. to some extent, anticipated this result when we failed to get any trace of an image with what we called our " normal developer." If , we look carefully at the negative, we shall notice, also, that some portions are represented by patches of clear glass in which no detail can be seen. This, however, would not happen if the negative were properly exposed, in which case some detail should be visible even in the deepest shadows, which are represented by the clear portions of the plate. The negative will, probably, also be wanting in gradation; that is to say, a print made from it would appear hard, with chalky high lights and heavy shadows, with an absence of " half-tone," as the intermediate shades are designated. From such a negative it is extremely difficult to obtain satisfactory prints, and, whenever it is possible, it is better to make a second negative, giving a longer exposure than before. When the reader becomes more proficient, and is able to develop a satisfactory negative, he will do well to make it a rule to at once destroy any plate which by mis calculation of the exposure, or from other causes, turns out to be under-exposed, for from such he will rarely be able to obtain even passable prints.
It was with a view to possible errors of this nature that we made the three successive exposures on the same subject recorded in the last chapter, and, with the object of acquiring more information on the subject of development, we will now proceed to develop the remaining plates.