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.
Tissue Runs When Drying. If the tissue runs during drying the drying-room is too warm. The room or drying-box must be kept about 75° Fahr., and at this temperature there should be a strong circulation of air, in order to insure rapid drying.
Judging When Print Is Printed. If the various directions given in the lesson have been followed, no difficulty should be experienced in judging the correct depth to which to print carbon tissue. The carbon does not require quite as much light action as the ordinary printing-out paper; it should be printed the same length of time required to make a good proof print from the same negative. The test for correct printing will come upon development.
Keeping Tissue Flat. The best way to keep tissue flat is to place it under a sheet of plate glass, or put it in a dry plate box and weight it down with a sheet of glass. If a large printing-frame is at hand, a piece of plain glass may be inserted in it, a sheet of opaque paper placed on top of this, and the carbon tissue laid on next, the back of the printing frame being replaced and fastened.
Refusal Of Tissue To Adhere To Support. In this case the tissue has either been left in the water too long or has been exposed to foul air or gases during drying. Place tissue and support under heavy pressure for one hour and then begin development in moderately warm water. Add hotter water until the pigment begins to ooze out; then strip off the back, lower the temperature of the water, and proceed with development.
Exposed Parts Of Pigment Not Dissolving. (a) First cause is due to too long drying; or fumes from the gas or lamp in the drying room. Always be sure that the room is well ventilated, and the room should be warmed without any danger of fumes emanating from the source of the heat. There must also be a good circulation of air through the drying-box, if the latter is employed. (b) Another difficulty may arise from the bichromate bath having turned brown both before and after use. This bath should be filtered, and frequently renewed. (c) Still a third difficulty may arise from the tissue not being printed soon enough after sensitizing. Endeavor to sensitize so that printing can be done the same day, or at latest, the day following. It is often convenient to sensitize the tissue in the evening for use the next day.
Cannot Dissolve Pigment In Shadows. The tissue is over-exposed. To secure the best possible results the temperature of the developing water should be constantly increased or a little ammonia may be added. If the details do not then appear a shorter exposure is the only remedy.
Image Will Not Dissolve At All. If even at the increased temperature the image refuses to dissolve in the developing water, the picture has been completely over-exposed. The only remedy is to make another print, giving a shorter exposure.