When dry, the paper should be laid face down, upon a polished litho. stone, and be pulled through the press three or four times, so as to get the surface as smooth as possible, and insure absolute contact. {133}
This must be done in a yellow light, or in a room lighted by gas or oil light.
The paper is now placed in contact with the negative, in a printing-frame, and exposed to light; the exposure for such paper should be from five to fifteen minutes.
Note well that these paper transfers are printed from negatives taken direct in the camera, without the intervention of the mirror, therefore negatives suitable for printing paper transfers will not do for printing upon zinc, or vice versa.
The progress may be watched by undoing one side of the back of the frame, and examining the image in the dark room; but in damp weather this should not be done too often, as the paper may expand or contract, and blur the image.
The exposure to light under the negative being complete, the print is removed from the frame in the dark room, and is next coated with a thin film of ink as follows:
A smooth litho. stone is carefully coated with a fatty ink by means of a leather roller, extreme care being necessary to insure an even coat of ink over the stone; this being attained, the exposed print is laid face down (the room being lit by yellow light or gaslight) upon the inked stone, then a piece of backing paper laid upon it, and pulled through the press, with a good nip upon it; pull it through twice, then reverse the stone on the press, and again pull through twice, which will leave a fine, thin film of ink upon it. Now take the inked print, and place it in a tray of clean, cold water, allow it to remain therein for five minutes, then lay the print upon a piece of glass, and rub it gently with a pad of cotton-wool—previously wetted in the water. This will remove the ink from those portions of the paper that were protected from the action of light by the opaque portions of the negative, representing the whites of the original.
The application of the pad of cotton-wool is continued until the whole of the picture is cleared from superfluous ink, and the lines composing the image are evenly coated with ink. The ink adheres only to those portions of the paper which the light has acted upon, through the negative.
Now wash the transfer under the tap, then hang it up to dry. When dry it is ready for transferring to stone or zinc.
To transfer to stone or zinc, place the transfer first of all in the damping book, and when limp place it upon a clean, cold, polished stone, and pull it through the press. {134}