A Manual of Photographic Chemistry, Including the Practice of the Collodion Process

by T. Frederick Hardwich

4. Use of glasses improperly cleaned.—This cause is perhaps the most frequent of all, when the film of Pyroxyline is very thin and the Bath neutral. After glasses have been long used it is often difficult to clean them so thoroughly that the breath lies smoothly; but the use of Potash gives the best chance.

MARKINGS OF VARIOUS KINDS ON COLLODION PLATES.

1. A reticulated appearance on the film after developing.—When this is universal, it often depends upon the employment of Collodion containing water. Or, if not due to this cause, the plate may have been immersed too quickly in the Bath, and the soluble Pyroxyline partially precipitated.

2. Oily spots or lines.—a. From raising the plate out of the Nitrate Bath before it has been immersed sufficiently long to have become thoroughly wetted.—b. Removal of the plate from the Bath before the Ether upon the surface has been washed away.—c. Redipping the plate in the Nitrate Bath after exposure to light, and pouring on the developer immediately; if a few minutes be not allowed to drain off the excess of Nitrate, the Pyrogallic Acid will not amalgamate readily with the surface of the film.—d. From the Nitrate Bath being covered with an oily scum, which is carried down by the plate. Draw a slip of blotting-paper gently along the surface of the liquid before using it.

3. Straight lines traversing the film horizontally.—From a check having been made in immersing the plate in the Bath.

4. Curved lines of over-development.—By employing the developer too concentrated; or by not pouring it on sufficiently quickly to cover the surface before the action begins; or by using too little Acetic Acid, and omitting the Alcohol. The addition of Alcohol to the developer will not be required as a rule when the Bath is newly made; but when much Ether has accumulated in it, the developer has a tendency to run into oily lines, unless containing Alcohol.

5. Stains from too small a quantity of fluid having been employed to develope the image.—In this case, the whole plate not being thoroughly covered during the development, the action does not always proceed with regularity.

6. Irregular striæ.—From fragments of dried Collodion accumulating in the neck of the bottle, and being washed on the film; to avoid this, the finger should be passed gently round the inside of the neck before use.

7. Markings like those represented in the woodcut.—They are caused by using an inferior sample of Pyroxyline made from too hot acids, and are most seen when using an old Bath.