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.
Examining The Print. The greatest of care must be exercised in examining the print during printing, it being necessary to keep the margin perfectly white, as the surface is very sensitive and is easily "flashed." If you examine the print in strong light, the part exposed to the light may become tinted. For this reason, it is always advisable to examine collodio carbon paper in subdued light. When printed lay the prints flat, face down, in a perfectly light-tight box or drawer.
Washing The Prints. As this paper is extremely heavy, it requires more washing to remove the preserving chemicals and unused silver salts than is necessary with other matte surface paper of lighter weight. Plenty of water should be used in the tray as this paper does not curl readily on account of its thickness. In the winter months, or in cold weather, the chill must be taken from the water. It requires at least eight changes of clear water to thoroughly wash prints and prepare them for the gold bath. To leave the prints in running water will not accomplish the desired results. They must be picked over by hand carefully between each change. After careful washing prints are ready for the toning bath.
Gold Toning Bath. This bath should be prepared according to the formulae given in the preliminary instruction. The acetate of soda is a very weak alkali, in fact a neutral chemical, and on account of its mild alkaline qualities it is possible to use it in larger quantities and more freely than any of the other alkalies. The use of strong alkalies as restrainers tends to give muddy whites. Although the alkaline action of acetate of soda is weak and its retarding or restraining quality powerful, it would not affect the gold bath to any great extent unless it were allowed to stand for a considerable length of time after being added to the bath. In order that the action of the bath be uniform at all times, it is advisable to allow the gold bath to ripen for a number of hours before using. If possible, the bath should ripen for twelve hours.
Toning In The Gold Bath. When the bath is ready for use, pour the entire contents into the toning tray and before proceeding with the toning, place in a graduate 3/4 oz. gold solution and add thereto 1/2 dram of borax solution. Allow this to stand for five minutes and add it to your toning bath, stirring the solution with the hand, after which add 1/2 teaspoonful of common salt. The salt will, to a certain extent, prevent the whites from bleaching and assist in making the tone more even. Next place a piece of red litmus paper in the bath and add gradually a little of the Solution No. 3, or borax solution, sufficient to turn the red litmus paper blue in about 2 minutes. Remember the gold bath must always be alkaline. If the amount of Solution No. 3, or borax, added does not perform this work in the given time, add more of the solution and continue to add a little at a time until the red litmus paper does turn blue. As the water in various sections of the country requires more or less of this solution, exact amounts to use cannot be given. However, there is one thing certain, a gold bath will not work properly unless it is slightly alkaline. It must turn red litmus paper blue in at least 2 minutes.