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The Dark Room - Developing, Printing, Double Printing, Retouching, Exposures

( Originally Published 1902 )

THE DARK Room.— A comfortable, airy dark room, though not essential to good work, is nevertheless highly desirable. Much excellent work is done under the most adverse conditions — plates are developed under beds, in bath-rooms, and in all manner of places; but that is no reason why, when it is possible, we should not have a room adapted to, and solely for, developing. Such a room need not be large ; four by five feet will do, though it is better for being a little larger. Do not on any account have it in the attic, unless you expect to do all your developing at night. Even then in hot weather you will find it anything but comfortable. The cellar is of all places the most desirable: it is nearly always cool in the summer, and if there is a furnace, it is quite comfortable in the coldest weather.

To make a temporary and easily constructed dark room, use two thicknesses of red building-paper, supported on a rough but rigid framework. The door may be most easily and safely made by taking three thicknesses of black or red Canton flannel, or some such material, and hanging it so that the edges of the cloth overlap. If the bottom has a wide hem filled with shot or sand, it will keep the curtain in close contact with the floor. The window is easily made by cutting a hole of the desired size and covering it with ruby cloth and orange paper. A lamp on a bracket outside will give the best and most steady light without heating the room. An extra piece of ruby paper or cloth should shield the light when isochromatic plates are being used.

If by tapping the water-pipe you can have running water, do so, as you will find it is well worth the small cost. A plentiful supply of water is the way to be sure of having everything clean, and cleanliness in photographic work counts for a great deal.

Inside the dark room the shelves should be arranged so that there will be a place for changing plates, a place for the developing trays, a small shelf for chemicals and graduates, and another shelf below all the others for the fixing-bath. Having this below the shelf on which the developing is done insures one against the possibility of having drops of hypo fall into the developer.

DEVELOPING.— While it might be taken for granted that the reader knows how to develop, still a few words may be said on the subject for the benefit of the beginner. Developing a plate is, briefly speaking, subjecting an exposed plate which holds a latent image to the action of certain chemicals which will reduce the bromide of silver to metallic silver—in other words, the developing agent causes the image to appear. The image will, of course, appear re-versed; that is to say, the objects which in nature are black will show transparent, while the white objects become black. This is caused by the action of light on the sensitive film: white, reflecting more light, acts energetically on the film, while black, reflecting as it does no light or scarcely any, has correspondingly little effect on the film.

Now, of the important considerations in making a negative, the first is to have it correctly exposed; the next is to use the developer best suited to the subject and the plate. There are so many developers today that it is no wonder the beginner becomes confused in trying to select the best." It is not so very long ago (up to about 1880, I think) that pyro and ferrous oxalate were the only two ; then came hydroquinone, which in turn was followed by the vast number which we see today. Some of them are good, but as a rule they are too violent. Pyro still holds its own with those who do not object to its finger-staining properties. With each brand of plates the makers give the formula best suited to the plate, and we cannot do much better than follow their directions. For my own part, I prefer pyro to all others for general work. Occasionally, for a very much under-exposed plate, edinol or metol or some such developer may be used with advantage, especially in hot weather.

In developing a plate, one should always keep it under control and watch it carefully, so that it may be removed when the proper density is reached. Underexposed plates need less acid and more water, and overexposed plates require less alkali, a stronger developer, and a small quantity of restrainer, such as bromide of potassium (ordinary salt will do in an emergency). With a plate correctly timed the quality may be regulated by the relative proportion of the ingredients. Thus when the developer is weak in alkali or over-strong in acid, the plate will give the effect of under-exposure, i.e., will be hard, with decided contrasts and little detail in the shadows; whereas, if the proportions were reversed, so that the alkali predominates, the plate would be flat, lacking contrasts, as in the case of over-exposure. A very weak developer will have the same effect.

A much overexposed plate may be saved by being placed in a bath containing a small quantity of re-strainer and the developing acid, no alkali being used. This bath should be kept in constant motion, or else the plate will have irregular, wave-like markings. When removed from this bath, replace the plate in the ordinary developer, containing some re-strainer, and carry the development much further than usual. Under-exposed plates may with advantage be placed in a weak alkali bath for as much as half an hour before development, and then developed slowly with a rather weak developer.

If a plate is too dense, it may be reduced, after being thoroughly washed, by putting it in a bath containing about three per cent. of persulphate of ammonia, then thoroughly washed. A plate that is too thin but has detail may be improved by intensifying ; but an underexposed plate having strong high lights and transparent shadows should be reduced rather than intensified. A good bath is made of a saturated solution of bichloride of mercury. When thoroughly whitened, rinse the plate and blacken it in a weak bath of aqua ammonia or sulphite of soda. The plate must be free from all trace of hypo, other-wise there will be yellow stains or irregular intensification.

In all cases be sure to dust your. plates carefully before placing them in the tray. Wash the plates thoroughly before fixing, and fix with fresh hypo bath, except when the weather is hot ; then the acid fixing-bath recommended by the Cramer plate-makers should be used. It hardens the film and keeps well, and allows of any after treatment that may be necessary for the plate. Another good hardener is fôrmaline (I part to 16 of water). This may be used either before or after fixing. Its keeping qualities are good, and it may be used repeatedly, allowing the plate to remain in it for from one to three minutes.

PRINTING.—In making a negative the prints must, of course, be thought of and the plate made that will best suit the paper one expects to use. Each kind of paper requires a certain quality of negative. Although these qualities cannot very well be expressed in writing, they will soon be discovered. The extremes may be said to be albumen, which requires a strong, dense negative, and velox, which gives the best results when the negative is thin and full of detail.

For most printing-out papers (papers which show the image while printing) the printing should be done in the shade if the plate is thin, and in strong sunlight when a dense plate is being printed from. Subdued light increases contrast, strong light decreases it.

Local printing, which often saves a picture, is accomplished by letting the light strike the plate locally, being careful not to have hard edges. A piece of cardboard with a hole cut in it will enable one to concentrate the light on the parts requiring the most printing. Do not, however, place it too close to the plate.

A very flat skv is much improved by allowing the light to fall on the paper very gradually (after the printing is finished and the paper removed from the frame), letting the upper part become fairly dark, while the lower part remains light. So much can be done by manipulating a print ; in skilful hands a poor negative may be made to yield a very fair print, but only after a great deal of practice can much be accomplished.

DOUBLE PRINTING.— There are times when the background of a picture may have been injured, while the central object, be it a person or an animal, is quite clear, or perhaps it is desirable to alter the surroundings of an object. In order to do this, double printing is resorted to. Two negatives are used, one of the background and the other of the figure. (Be sure the two are in correct proportion.) This latter negative is painted out with opaque colour, leaving the figure untouched. Of course the edge must be very carefully followed. Then a print of this figure is made, and that is carefully cut out, thoroughly darkened, and laid against the background negative in exactly the place where it is needed. A print is now made from this negative which, when done, will leave a white space exactly the size and form of the figure. The next step is to fit this print against the figure negative and make a print from it. The resulting picture will show no joint, if the work has been properly done. A little retouching on the edge will easily cover up any small defects in the joining.

RETOUCHING AND SPOTTING.— Both negatives and prints may frequently be improved by a little judicious retouching: an outline accentuated, a little detail worked up, or a high light strengthened will often do much to enhance the beauty of a photo-graph and render it more suitable for reproduction. This retouching may be done on either the negative or the print, or both.

For the negative a balsam preparation known as retouching-fluid is rubbed softly over the film. This gives it a " tooth," so that a lead-pencil will mark it. When fine work is needed, such as in working up the hair on an animal, a very hard and finely pointed pencil should be used, HHHH being none too hard. For softening shadows H is hard enough. Occasionally, where broad masses of shadow are to be held back, a very thin and light wash of pale aniline yellow, applied with a brush, will answer.

In working up a negative, if one has not a regular retouching-frame, lay the plate in a printing-frame, prop it up so as to face a window, and place a piece of white paper in such a way as to throw a reflected light against the plate.

Spotting a negative is simply filling in the small clear spots that are caused either by dust or by bubbles in the developer. The medium used for this is either a preparation known as " opaque," or water-colour paint, or even Indian ink. The density of the paint must, of course, correspond with that of the plate at the place where the hole is in the film.

For retouching prints both paint and pencil are used. For the platinum papers a soft pencil or charcoal gray and white (water-colour will serve. With the smooth, glossy papers, water-colours mixed with a little albumen or gum arabic will allow of almost any degree of retouching. In doing work for reproduction, it is often necessary to accentuate detail in the shadows. It should, however, be done carefully, as the photographic effect is easily lost.

EXPOSURES.— There is but one master who can teach us how to expose a plate correctly under all conditions. That master is experience. Correct exposure depends so much on the quality of print we want that it is impossible to give any rules on the subject. An under-exposed plate yields a hard negative with strong contrasts, while the result of over-exposure is flatness — lack of contrast. To a limited extent these defects may be corrected in the developer, but if the plate is very much under-timed, no power can save it. On the other hand, a very much over-exposed plate may, with care, be made into a good negative. So if you are in doubt about what expo-sure to give, be sure to give enough — too much rather than too little.

The Optics Of Photography
Photographic Printing Processes

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