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.
Printing. After loading your frame with the carbon tissue, again place another narrow strip of ordinary printing-out paper on your actinometer and clamp it firmly. Place both frames in the light to print. A good, strongly diffused light is best. It is not advisable to print in bright sunlight. Do not examine the frame containing the carbon tissue; judging from your former experience you should have learned, almost to the minute, how long it will require for this negative to print. Within a few minutes of the proper time examine your actinometer or the strip of paper placed in the frame containing the actinometer. Examine it closely, and if the step or number to which you have calculated it necessary to carry your print has not yet been tinted, immediately place it in the window and continue printing; examine it again in a short time, and continue doing so until you have secured the proper tint.
Caution. It is advisable for your first experiments to withdraw the negative with the carbon tissue while you are examining the actinometer, as you are apt to over-judge the printing, for the negative containing the carbon tissue will continue to print while you are examining the strip of paper, and if you examine the paper quite frequently the carbon tissue will have gained upon you in time of exposure. When you have secured the proper number to print to, withdraw both frames, remove the carbon tissue from the frame, and if you so desire you can place this sheet in a box in the dark-room and make a second print before you start to develop.
Temporary Actinometer. If you do not care to go to the trouble of preparing an actinometer, select another negative similar in density and gradation to the one from which you intend making the carbon print, and use this second negative in place of the actinometer. Place the first negative with its "safe edge" in a printing-frame, and place a piece of sensitive tissue upon it and fasten the back of the frame in place. In another printing-frame place the second negative, and on it a piece of ordinary printing-out paper. As you cannot look at the carbon tissue while it is printing, the printing-out paper on the second negative will act as a guide for you to follow. A visible image will soon appear on the printing-out paper. Printing must be allowed to continue until there are signs of detail even in the highest lights of the guide print. It is impossible to say much more than this, but after a little experience you will be able to judge exactly how far to carry the guide or test print. It is advisable to develop this carbon print before proceeding to make a second one. The guide print should be taken in at the same time and placed in a dark place, until you see if the exposure was correct or not.
Preparing The Developing Bath. Into one of the galvanized-iron trays pour hot water heated to about 80° Fahr. Prepare another tray ready for water that should be heated to 110° Fahr. In a third tray containing clear, cold water, place your support, whether paper or celluloid. Beginners are advised to use celluloid, for the reason that should they fail in the first attempt the celluloid can be used over again by washing off the surface. A white matt celluloid should be used.