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.
Impure Or Grayish Whites. Lack of bromide in the developer - add a few drops of a 10% solution of bromide to the developer. Under-timed prints which have been forced in the development. Or, possibly the paper has been fogged by having been brought too near the light while the printing frame was being loaded, or when the paper was developing.
Greenish Tones. A developer too weak or too old; too much bromide in the developer; oxidized developer; or overexposure. Use a more concentrated developer, or add less bromide. A strong and fresh developer permits the use of more bromide than a weak one, without producing greenish black.
Brown Tones. When the brown tones show, while the print is in the developer, it may be due to over-exposure and an excessive amount of bromide, or an old or incorrectly compounded developer. If the brown tone appears after immersion in the fixing bath, it may be traced to impure sulphite of sodium, or to too warm a fixing bath.
Contrasty Prints (Lacking In Detail). If negatives are too harsh, use Normal or Professional Cyko, which works softer than the Contrast grade. A softer effect may be obtained with any grade of Cyko by increasing the exposure, or using a more dilute developer, or both.
Flat, Muddy Prints. Over-exposure. Negatives too thin or too weak. Use Contrast Cyko, which is more contrasty than Normal or Professional Cyko. The trouble may be due in some cases to the developer being too weak.
Prints That Are Too Dark. Over-developed. (See also Grayish-Whites.) Remove prints from the developer sooner.
Yellow Or Brown Stains. The developer has not covered the print uniformly; or too long a time has elapsed between developing and fixing; or the prints were not kept in motion when first immersed in the fixing bath. Staining all over the print is the result of trying to force the development of under-timed prints, or using a developer too weak, or too old. The print may not have been fixed or washed sufficiently. In some cases it is due to the fact that the water contains too great a proportion of iron. It is easy to determine when the trouble is due to incomplete fixing, because the print will have a sweet taste. Always rinse prints before fixing. We may here remark that one of the most common troubles met with in printing gaslight paper is staining; but this difficulty is seldom present when making Cyko prints, unless the worker is extremely careless.