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.
Washing. It is absolutely necessary to thoroughly wash the prints before they enter the first toning bath. Eight or ten changes, handling each print separately in every change of water, is generally sufficient to remove the preserving chemicals and free silver, and thus thoroughly prepare the print to enter the gold bath.
143. Gold Toning Bath.
Chloride of Gold.........................
Acetate of Soda........................
Pure Hot Water................................
Preparing The Gold Toning Bath. In a two-quart bottle place 40 ozs. of pure water and add to this 1 1/2 ozs. of Stock Solution No. 2 (Acetate of Soda). This bath should be prepared 10 hours before use, if possible, in order to allow it to thoroughly ripen. If, however, it is impossible to wait that length of time before toning, it is permissible to place an unwashed proof print in the bath and permit it to stand for two hours. The free silver from the print has a tendency to hasten the ripening of the solution. As acetate of soda is a very weak alkali, it will have no effect upon the toning, unless the solution is allowed to stand at least two hours to ripen.
148. When ready to use the gold bath, pour the bath mixture into the toning tray. Then pour into a graduate 3/4 oz. of the Stock Solution No. 1 (gold) and 1/2 drm. of the Stock Solution No. 3 (borax), allowing them to stand 5 minutes; then empty into the toning tray and add to the bath 1/2 teaspoonful of common table salt. Place a piece of red litmus paper in the bath, and cautiously add a little of Solution No. 3 (borax), carefully stirring the bath while adding. If the red litmus paper turns blue in two minutes enough of the borax solution has been added. Care must be exercised not to add more of the borax than is absolutely necessary, but there must be enough alkali in the gold bath to at least turn the red litmus paper blue.
Toning In The Gold Bath. The prints should tone in from 6 to 8 minutes and if they do not tone in this time, more gold solution should be added until the correct time of toning is reached. Do not make the bath too strong as the prints will tone before the whites clear up if there is too much acid action. If the prints bleach in the highlights before the shadows are toned far enough, add more of Solution No. 3 (borax) regardless of the color of the litmus paper, bearing in mind that the alkali acts as a re-strainer on the highlights. The amount of alkali to use is the quantity necessary to keep the whites from bleaching while the shadows tone. An acid gold bath not only bleaches out the detail in the prints, but it also produces pink whites and weak shadows, and tones slowly. The color of the resulting picture is to a very great degree dependent upon the tone of the print when it leaves the gold bath. For the average matte surface paper the prints should be toned to a purple, but never a blue color. More direct instruction for toning in the gold bath will be found under the detailed instruction given in the following chapter.
150. Prints must be carefully handled over in 3 changes of clear water before placing in the platinum bath. This is essential, as none of the free gold which might be on the print should be carried to the platinum bath, as gold precipitates platinum and unless prints are well washed, platinum will be precipitated on the bottom of the tray and not on the print.