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.
Acetate Of Soda. Acetate of soda is a very weak alkali, almost a neutral chemical. The fact of its being one of the mildest alkalies permits us to use it in large quantities. As strong alkalies give us muddy whites when using them as restrainers, we, therefore, use acetate of soda in large quantities, and while its alkaline properties are mild, its retarding qualities are powerful; but acetate of soda has no beneficial effect upon a gold bath, unless, after adding acetate, the bath is allowed to stand for at least two hours to ripen.
192. Lack of Alkali in the Gold Bath will give weak shadows, pink whites, blue half-tones and bleached prints. If you do not get strong, rich shadows in the print from the gold bath, you cannot get them in the platinum bath. Insufficient toning in the gold bath, leaving the shadows a bricky red, will give flat prints, lack of brilliancy, yellow whites and muddy shadows, resulting in a brownish olive tone. This, in connection with lack of proper amount of alkali, is the cause of the majority of troubles in the gold bath. A gold bath should be made up from four to twenty-four hours before using. An excellent plan is to make up a fresh bath after you have finished toning, for use the next time, adding only enough gold to ripen the bath, say one grain, and a few drops of the alkali. Some printers put a print into the bath just as it comes from the frame, which furnishes enough silver to ripen it. When ready to tone, add gold and the proper amount of alkali to make speed of bath from five to eight minutes. A ripened bath will work much more smoothly than a fresh one. When acetate of soda is used in a gold bath, it is for the purpose of holding the strength and brilliancy of the tone.
193. When the water used is extremely alkaline it is best to use the gold alone without neutralizing, thus first acidifying the toning bath; then just before toning add the borax to make the bath alkaline. The reason for this is that the alkali found in the water is not of the proper kind and will give poor results.
194. The temperature of the toning bath should be between 65 degrees and 75 degrees Fahr.
How To Tone Different Kinds Of Prints. Vigorous prints will stand vigorous toning. Weak prints require gentle toning. If prints tone too rapidly the bath is too strong in gold, and can be corrected by adding more water. Uneven toning comes from insufficient washing before gold bath; gold too strong; lack of alkali; bath being too warm; prints sticking together in the bath; insufficient bath; not keeping prints moving; also from insufficient salt in gold bath. If prints tone too slowly the bath may be too weak in gold, or it may be contaminated with foreign impurities, or be too cold. In the gold bath flat-looking prints may be caused by the use of too much salt, too much alkali, or by impurities in the water. When from impurities in the water, a few drops of nitro-muriatic acid (nitric acid one part, muriatic acid two parts) is added to acidify the toning bath and then the proper alkali employed, this difficulty may be overcome.