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.
Development. All copy-negatives receiving a full exposure must be treated accordingly, and be developed slowly and considerably farther than for ordinary work. In order to avoid fog and retain the snap throughout the development we advise adding three or four drops of a 10% solution of Bromide to your normal developer. Mix well and proceed to develop in the usual manner. Remember that plates from copies should be carried at least one shade farther in developing than regular work. Work very carefully, and once you have produced a good copy-negative you will have a key to guide you in your future work.
Developing Special Plates. Great care must be exercised when developing color-sensitive plates. Either cover your developing tray or develop away from the ruby-light, and when judging the development do so as quickly as possible, as the plate is sensitive even to ruby-light and will fog in a few seconds. Remember these special plates are extremely sensitive to all colors; so keep them in the dark during development. These special plates usually give the best results when developed according to the formula accompanying them, and should be handled in that way. The plates, after developing, should be fixed, washed and dried in the usual manner.
Copying Oil Paintings Or Water Colors; Or Any Colored Objects, Such As Colored Lithographs, Etc. For the copying of these, or any good, clear prints, with much color, use a slow Isochromatic plate, and time as long again as with ordinary plates. For old faded pictures, tintypes, or soiled pictures of any kind, use an ordinary slow plate, time fully, and develop in normal developer, with a few drops of Bromide added.
488. Be careful to develop color-sensitive plates in either a covered dish, or develop away from the ruby-light, as they are apt to fog and mislead you, being sensitive to the ruby-light. When copying paintings, unless they are very bright and of a high color, give fully ten times the exposure you would give uncolored prints. Sometimes it requires ten minutes in a strong light to secure the best results.
489. When copying from glossy prints you will find that they will not require as much time as dull surface ones. When reducing from a large picture you will find it will not require so long an exposure, for the reason that the lens is nearer to the plate or ground-glass and the illumination is greater. Exercise great care, when copying large pictures to a small size, that your picture or drawing is placed absolutely perpendicular and parallel with the camera. Oil paintings or colored pictures of any sort copy best on good bright days. When copying drawings you require a smaller stop than for other pictures, as each line must be perfectly sharp. Illustrations Nos. 3 and 4 show copies from a colored Daguerreotype. One exposure was made with an ordinary plate, while the other was made with an Orthochromatic. (See Page 157.)