This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Stripping Off The Backing Paper. The next operation is to remove the paper which forms the back of the carbon tissue, leaving the picture in an undeveloped condition on the transfer paper or celluloid. To do this, when you are sure the time is right as described in the foregoing paragraph, gently raise one corner of the paper with the point of a pin, or use the finger nails, and then catch hold of it with the fingers, keeping the print under water; then bend it right back and with a smooth, even motion, peel it off. If the corner will not pick up freely from the start, this will indicate that the film is not sufficiently softened; again immerse it in the hot water for another minute or so and try it once more. Do not fear damaging the tissue, even should you fail the first time, as it is by experience that you learn.
160. This operation may seem rather a rough sort of treatment, and one that you would think would injure the delicate surface of the print underneath it, but such is not the case. Moreover, this manipulation should not be carried out in a nervous or hesitating manner. We do not advise being rough about it, of course, but always strip it quickly and straight. The paper as it comes off may bear signs of the picture or it may not. It may also shows what seems to be bubbles and blemishes, from which you may be led to suppose your print was a failure, but it by no means follows that this is the case, and you may throw away the tissue paper backing, discarding it entirely. Concentrate your attention to the transfer paper or celluloid, which now lies in the warm water with a mass of slimy looking pigment upon it. This mass contains the picture and the surface is very delicate. From now on to the finish no solid matter must come in contact, however gentle, with the face of the image.
Caution. It is extremely important, when removing the backing from the transfer paper, not to hesitate, but draw the tissue evenly with one continuous draw, for should you hesitate and pull in jerks, wherever you stop there will be a line across the face of the print, which will be somewhat difficult to remove when developing.
Finishing The Development. The water in the tray will by this time have cooled somewhat and should be discarded. Having previously provided a fresh supply of water in an ordinary tea-kettle, at about the original temperature, hold the print over the tray and from the tea-kettle pour the water in a gentle stream over the face of the print.
It is quite possible that the picture will almost immediately begin to make its appearance, as the excess of the pigment gradually washes away where it is not required to form the image. In other words, the insoluble portions of the pigment remain in contact with the transfer paper, while the soluble particles are dissolved and washed away. Continue to pour the fresh warm water gently over the print; or you may turn the print face over and allow it to flow face downward on the warm water, and in this way it will develop itself. Should the development proceed too slowly, then gradually increase the temperature of the water or transfer the print to your second tray containing water heated to 100° or even 110° Fahr., and, with the hand, spray the water upon the print. At this stage hold the print out of the water. The spraying of the water on the carbon will gradually eat away the black pigment until the entire image is developed, which will require from five to fifteen minutes. Do not make any attempt to stop development when the print seems to be about the right depth, as greasy looking spots will be the result, indicating that development has not been finished. On the contrary, go on developing as long as the warm water seems to be dissolving anything from the print. This is the only way you will be able to judge whether or not the exposure has been correct.
163. When the development is finished, rinse the print in cold water and with the finger gently rub the white edge or margin of the celluloid or paper support, cleaning it thoroughly before fixing.