American Photography Volume 6 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 edition. Excerpt: ... comes from decomposition of hypo. The trouble is that sodium sulphite in solution oxidizes to sulphate, which has not the power to protect the hypo from the acid. Even pure sulphite will fail if the bath stands for a time, and impure sulphite simply hastens the decomposition. You might make up a saturated solution of hypo in a large jar; take as much as needed for use, diluting it with an equal volume of water, and adding the liquid bisulphite. Spots; Exhausting A Developer; Drying Prints.--A. K., Westfield, N. Y., asks: (1) Why do my films have very small specks on them? I use the tank for developing. (2) How many 4x5 prints can I develop with three hundred ounces of M.-Q. developer of regular Eastman formula? (3) How are prints dried with alcohol? Ans.--(1) You should have sent a film showing the defect. Your question is too indefinite. The specks may be due to dust which settled on the film before, during, or after exposure; undissolved particles of developer; dirt in the water; lime salts, or air bubbles. (2) The number of prints you could develop might be anywhere from fifty to three hundred and fifty dozen 4 x 5. The only safe rule is to throw away the developer and mix fresh as soon as the color of the prints begins to fall away from the tone you like. Probably six ounces of developer in a 4 x 5 tray would develop from two to four dozen sheets of paper. (3) We do not advise you to dry prints by means of alcohol, as it might affect the color of the prints or even cut away some of the detail in the highlights and halftones. It is far better to dry the prints over a gas stove while spread face down on cheesecloth-covered stretchers. Tank Formulas.--A. N. asks: Can you give me a good formula for tank eikonogen-hydrochinon, also metol-glycin?...