Photography self taught

After exposure, the film or plate shows no visible change but the “latent image” is there and by the aid of suitable chemicals and solutions it can be brought out and made visible or in other words be “developed.” Such solutions are termed developers.

CHEMICAL PROCESS. This consists in the removal of the bromine or chlorine from the silver bromide or silver chloride of the emulsion where the light has acted, so as to leave the grains of metallic silver which constitute the photographic image.

Of the developing agents which are capable of bringing out the image, pyro, hydroquinone and Elon are perhaps the most commonly used for negatives, although Elon is seldom used except in connection with one or the other.

Although one of the oldest developers, pyro has long been considered one of the best for the development of films and plates. It surpasses other developers in the control it gives over the printing quality of negatives as the color can easily be varied from a blue-black to a slightly olive or yellowish tone. A slight stain image in addition to the silver image is desirable as thus the negatives will not need to be so dense as though they were blue-black. The present tendency is to use pyro either in connection with Elon or with Elon and hydroquinone. Beginners are likely to get the negatives a too decided yellow; also pyro if somewhat oxidized will stain the finger nails. An Elon-Hydroquinone combination is one of the most popular developers, and being non-staining it is especially good for tray development.

A solution of pyro, Elon, or hydroquinone and water, will develop so slowly that an alkali such as sodium carbonate is added to speed up the action. In the presence of an alkali, however, the developing agent quickly oxidizes, making the solution somewhat colored. To prevent this oxidation, a preservative such as sodium sulphite is added which keeps the developer clear without otherwise affecting its properties. In order to minimize the tendency to fog (the development of the unexposed grains of silver salts), a trace of potassium bromide, a restrainer, is usually added.

TANK DEVELOPMENT

Within recent years the tank method has come to be preferred by the majority of workers. If roll film is being used, a special tank developing machine consisting of a wooden box, a lightproof apron, transferring reel, and metal solution cup will be necessary (Fig. 8). No dark room is required. The film is wound into the apron according to instructions and transferred to the solution cup where it is left in the developer for a predetermined time. This is a logical scientific method, development being continued for a definite time in a solution of a given strength at a known temperature. It will produce a technically correct negative and in the hands of the average person will no doubt give the highest percentage of good results. If the exposure is at all within the latitude of the film, the negatives will be of proper contrast, differing in density according to the exposure and although requiring different printing times will give prints of similar quality.

Film packs may also be developed in special tanks but a dark room is necessary when loading them into the tank.

Cut films and plates are usually developed in open tanks and this operation must be carried on in the dark room. The work may be done either by the time and temperature system or the inspection method.

TRAY DEVELOPMENT

Tray development is not usually considered as convenient a method as tank development but it has its advantages and is used by many workers. Not only does it give an insight into the actual process, but it affords an opportunity for the pictorial worker to secure results other than an exact representation of the subject. Tray development must be carried on in a dark room which is entirely free from white light and which is illuminated only by a light such as given by a Brownie Safelight Lamp when fitted with a Series 2 Safelight.⁠[6]

Four trays are necessary, one for clear water, one for the developer, one for a rinse bath, and one for the fixing bath.

Many workers prefer to purchase their chemicals made up in small packages and ready for use with only the addition of water. This is a very convenient method. Others are interested more in the science of photography, and prefer to make up their own solutions from formulas. Of the many good formulas available but one will be given here⁠[7]:

Elon-Hydroquinone Tray Developer

For use dilute with equal parts of water. The temperature should be 65 degrees Fahrenheit.

Development. If roll film is being used it is first detached from the red paper on the roll, and then, one end being held in each hand, it is passed face down through a tray of clear water several times to eliminate air bubbles and to prevent curling. Next it is passed back and forth through the developer in the same manner, this motion being continued until development is complete.

Ordinarily the films should remain in the developer until the picture is about faded out on the side where it first appeared and begins to show quite well on the back. Longer development will not only make the negative denser but will result in more contrast or a greater difference in density between the highlights and shadows. Therefore development should be continued until the negative is of the proper density and contrast to give good prints on the type of printing paper which is being used. Naturally it will take some experience to know just when the correct point is reached. The negatives may be examined by holding them up in front of the safelight lamp but they should not be held there for more than a few seconds at a time.

Because of the extra transparent coating on film packs, the purpose of which is to lessen the possibility of scratching the emulsion on drawing the tabs, about 1–3 longer development is required than for roll film. Super-speed film also requires longer development. Panchromatic film, being sensitive to all colors, must be developed in total darkness or by the aid of a deep green light.

Rinsing. When developed, films are rinsed for a few seconds in clear water and then transferred to the fixing bath. The following rinse bath may be used instead of clear water and has the advantage that it will not only harden the films but will stop development at once.

The negatives should be left in this bath for two or three minutes, being moved about especially when first being immersed. The hardening bath should be renewed frequently.

Fixing. After the negatives are developed the particles of silver bromide which were not affected by the light are still sensitive and so must be removed by a process called “fixation.” Here the hypo (sodium thiosulphate) combines with the unexposed grains of silver bromide or other silver salts to form a compound which is soluble in water and therefore which can be removed by washing.

Either a chrome alum fixing bath or an acetic acid fixing bath may be used, but the latter will be given here as this formula is suitable for prints as well as negatives.

Acetic Acid Fixing Bath

The chemicals should be dissolved in the order given using water at about 125° F. Be sure that the sodium sulphite has completely dissolved before adding the acetic acid. After the sulphite-acid solution has been thoroughly mixed, add the potassium alum and stir until completely dissolved. Add the cold hardener solution (B) slowly to the cold hypo solution (A), stirring the latter continually.

The negatives when first being placed in the fixing bath should be moved about for a few seconds and then occasionally during the entire time of fixation. This should be for about 15 minutes or for twice as long as it takes to clear them of the white milky appearance. If not kept separated properly or if removed too soon the negatives will later discolor, probably showing yellow stain. Sixty-four ounces of this bath will completely fix the equivalent of 200 3¼ x 5½ negatives if the Alum Rinse Bath is used.

Washing. When removed from the fixing bath, negatives contain in the gelatin a number of chemicals which must be removed if permanency is to be assured. These include the hypo and other chemicals of the fixing and hardening bath and also other compounds formed by the reaction between the hypo and silver salts, and also possibly some carried over from the developer. Washing should be for 30 minutes in running water or for five minutes each in six changes of water.

Drying. Superfluous water together with any grains of dirt from the wash water should be removed from the film or plate by swabbing gently with absorbent cotton which has been saturated with water. Roll film may be hung up to dry in such a way that neither side touches anything. Drying should take place where there is circulation of warm, dry air, but not in the sunlight or where the temperature is too high or the emulsion may melt. Neither should the negatives be dried in a dusty location as any specks of dust will show up as white spots when the negatives are printed.

NEGATIVE DEFECTS

After the process of development is complete and the negatives are dry, it may be found that some of them have been underexposed or overexposed or underdeveloped or overdeveloped. The following table indicates the results that should be expected from variations in exposure and development.

Sometimes negatives are defective in some way and need treatment before being printed. Those that are too thin and flat, having a short scale of contrast as the result of underdevelopment, should be intensified. On the other hand if the negatives have been overexposed or overdeveloped they should be reduced. Formulas for these processes are given in Elementary Photographic Chemistry.