When the stone has been under pressure for a sufficient length of time, to allow the small traces of gum in the deepest shadows to attach themselves to the stone, the pressure is removed, the stone withdrawn, and the paper carrying the photographic print is carefully lifted up, leaving the bare negative image on a gummed ground. The stone is well dried, and covered all over with a greasy ink applied by a roller or otherwise. The ink is thus brought into contact with all parts of the stone or zinc unprotected by the gum.
The image is then washed out with turpentine, and the gum removed by a damp sponge, after which the stone or zinc is rolled up in the ordinary manner with a leather roller, and is printed from in the ordinary manner.
Of course, it will not be expected that the best results are obtainable by so simple a process. Perhaps in no other branch of work does an outlay of thought and time “pay” so well as in the practice of these interesting photo-printing methods.
CHAPTER V. PHOTO-LITHO. TRANSFERS.
TO DEVELOP PHOTO-LITHO. TRANSFERS.
To develop photo-litho. transfers on paper
Now the inked and exposed transfer is placed in water at 80° F., and allowed to remain for three or four minutes, when it is taken from the water and placed upon a plate of glass, and the superfluous ink is removed by means of a sponge dipped in the hot water. If the negative has been sufficiently opaque, and the exposure right, the image will quickly develop, the lines retaining the ink, while that upon the whites will come away.
Hot water is used where the coating is of gelatine only; if gum arabic, or albumen has been used, then, after inking up on the stone, the transfer must be developed in cold water, and cotton-wool used to remove the ink from the whites, rubbing very carefully with very little pressure.
Paper prepared with a thick coat of gelatine may be developed in another way; after removing it from the printing-frame, the transfer is inked up on the stone, then placed in a dish of cold water and left there for five or ten minutes; then removed and placed upon a thick glass slab, the end tucked under so that when placed on the bench the slab will press the paper and keep it in position. Now, with a sheet of clean blotting-paper, remove the water from the transfer, using pressure with the hands from the end tucked under the slab; then, with a glue roller, roll from the tucked under end until the image is developed. Instead of inking the transfer up when dry, the transfer may be placed in the cold water directly it is taken from the printing-frame, and allowed to remain for ten or fifteen minutes, during which time the image will swell, by the whites absorbing water. Now place upon the glass slab (one end being tucked under), and remove the superfluous water first with a {141} sponge, then with a damp cloth; now dip a sponge in transfer ink thinned to the consistency of cream by turpentine, and dab all over the damp transfer, then allow it to stand until the turpentine has evaporated. Next take the glue roller and roll the transfer until the whites are clear; only roll one way—i.e., from the end tucked under the slab.
The transfers being developed, they are rinsed with clean water, and hung up to dry in a current of cool air. If dried at too high a temperature, the transfers will be inferior, and difficult to handle.