A Manual of Photographic Chemistry, Including the Practice of the Collodion Process

by T. Frederick Hardwich

The Iodide and Bromide should be free from Carbonate of Potash, which is said to cause pin-holes in the Negatives. To ensure the absence of this salt, dissolve the total quantity of both Iodide and Bromide in the three ounces of water advised in the formula; then, previously to adding the Ammonia and Albumen, introduce an excessively minute particle of Iodine, enough barely to colour the liquid. The Iodine decomposes the Carbonate of Potash, but it must not be used in excess, since free Iodine possesses the property of coagulating Albumen. Iodide of Cadmium also coagulates Albumen, so that the Iodides of Potassium and Ammonium are the best.

Having mixed the ingredients in the order above given, introduce them into a bottle, and shake it violently until they have thoroughly amalgamated. Then transfer to a tall narrow jar; allow to settle for twenty-four hours, and draw off the upper clear portion for use. Particulars of this part of the process have already been given under the head of Albuminized Paper, to which the reader is referred ([p. 241]).

The ammoniacal solution of Albumen may be kept for some time in a stoppered bottle without much decomposition. If mucous threads form in it, filter through fine linen.

Mode of applying the Albumen.—Cover the moist film with the Albumen in the same way as advised for Collodion ([p. 216]), pouring on at once a sufficient quantity to cause it to spread in an even and undivided sheet; otherwise a veined appearance may be produced, which will show in the development. Return the excess of Albumen into the bottle, and pour it once again upon the plate: the film will remain clear and transparent, if the whole of the Nitrate of Silver has been properly washed away from the Collodion. Lastly, stand the plate nearly vertically on blotting-paper to dry. This will occupy five or six hours; but the process may be hastened by artificial heat.

After the Albumen solution has been used to coat a number of plates successively, it becomes diluted with water; the result of which is, that unequal intensity of image is produced at the upper and lower edge of the film.

The iodized Albumen plates are at this stage of the process nearly or quite insensitive to light, and may be preserved unchanged for many weeks.

Sensitizing the Albumen film.—When the plate has become thoroughly dry, it is again introduced into the Bath of Aceto-Nitrate of Silver, and allowed to remain for one minute: then washed with water in the same manner as before, but with even greater care, in order to obviate clouding in the development. If blisters should form on drying, it will be found useful to hasten the process by holding the plates to the fire—or a hot iron may be placed in the centre of a covered box and the glasses reared up round the sides. They will thus dry quickly, and there will not be time for the Albumen to swell much by imbibition.

Exposure in the Camera.—This may be performed at any period within a few weeks from the date of preparation of the plates. For a landscape view with a small Stereoscopic single lens, allow about three minutes in the winter, or one minute and a half in the summer.

Development of the image.—This can be deferred as long as fourteen days after the exposure, with successful results. Pour water over the plate until the film is thoroughly wetted; then cover it with a solution of Pyrogallic Acid containing one grain of the acid to the ounce of water, and twenty minims of Glacial Acetic Acid. Two drops of a neutral solution of Nitrate of Silver made with forty grains of Nitrate to the ounce of water must be previously added to each fluid drachm of the Pyrogallic. The development, in the case of a landscape view taken with sunlight, commences almost immediately, and may be completed in about ten minutes, but the time occupied in developing will vary greatly with the length of exposure, the quantity of Nitrate of Silver, and the nature of the subject copied—a badly lighted interior, for instance, often taking an hour or longer to appear in all its details. If the developer should discolour before the proper intensity has been obtained, pour it off and mix a fresh quantity.