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.
Negative From Transparency Flat. If the transparency is a weak, thin one, the enlarged negative will also be weak, thin and flat. If over-exposed, whether in making the enlargement from a large transparency, or enlarging from a small transparency, and the proper method in developing for over-exposure is not observed, the result will be flat negatives. When developing negatives from thin, flat transparencies use a strong restrained developer; this will assist in giving contrast.
Enlarged Negative From Transparency Showing No Detail In The Shadows. If the transparency has no detail, which would be the case in an exceedingly contrasty or under-exposed transparency, there would be little or no detail in the enlarged negative. Under-exposure in the enlarged negative would also cause a lack of detail.
High-Lights In Both Transparency And Enlarged Negative Hazy And Flat. A certain sign that both the transparency and enlarged negative are over-exposed; or if the transparency is brilliant, has clear shadows, and only the enlarged negative has highlights that are flat and hazy, this would indicate that the enlarged negative was over-exposed. By using slow plates for making the transparencies the flatness will be overcome as there is much more latitude to the exposure.
Shadows Not Transparent Enough. This effect is produced both in the transparency and enlarged negative by over-exposure. If, however, the transparencies are over-exposed or overprinted, the enlarged negative is sure to have shadows that are not transparent, even though the enlarged negative be properly exposed.
When Using Artificial Light Other Than Arc-Light The Entire Ground-Glass Not Evenly Illuminated. By using opal glass in place of ground-glass and placing the light far enough away from the glass, this difficulty can be overcome almost entirely. It is harder, however, to evenly illuminate the negative by artificial light than it is by daylight. A good reflector is necessary; therefore, line the entire box that holds the light with asbestos or tin. The white box will then act as a reflector and more evenly illuminate the ground or opal glass.
Proper Exposure For Transparencies. When printing the transparency, whether by contact or by enlarging, a number of experiments will be found advisable. Be guided by the results thus obtained and govern the exposure for all future results accordingly.