American Photography Volume 12 download pdf

American Photography Volume 12 by Camera Club of New York

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. 1918 Excerpt: ... believe that carbon tissue needs a plucky negative take one of his which, while having ample gradation, is a soft one--the kind, in fact, which makes the best enlargement. Let him take some warm block or sepia tissue, and sensitise it by immersing it for three minutes in a solution of potassium bichromate of a strength of seventy grains to ten ounces of water, which is approximately one and a half per cent. If it is done in the evening, and the tissue is left freely exposed to the air in a perfectly darkened room, it will be dry the next morning, and can be printed at once. It will be found to give a bright, strong print without any trouble. After carbon tissue has been sensitised it speedily alters in character. If kept long enough it becomes insoluble and useless; but for a few days it is in good working order, and its character varies according to the time that has elapsed since it was sensitised. The gradation is at its best on the second or third day. Very freshly sensitised tissue tends to give hardness, the lighter tones being proportionally too light; stale tissue, on the other hand, gives flat results. By cutting a scrap off the piece, putting it in cold water for a minute or so, in the dark, and then putting it in warm water, one can see at a glance if it is in good working condition; if sc. the pigmented gelatine will entirely dissolve, leaving the paper quite white. It is not a good plan to sensitise more of the tissue than there is a reasonable prospect of using forthwith; as, in spite of what has been written as to the possibilities of keeping it in good working order, it is sure to cause trouble. If sensitive tissue is to be kept at all, it must be stored out of reach of damp; and it might be thought that a platinum storage tube with some ca...

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