The Influence of pH on Washing Films after Processing

Advantages stated to be obtained by adjusting fixing baths and wash-water to the isoelectric point of gelatin have been claimed. The advantages are said to be shorter washing time, less swelling and retention of water, with consequent improvement in the jelly strength of the wet emulsion, and reduced drying time. In the present investigation the conditions as to pH of the solutions, and wash-water, rate of flow of water, residual thiosulfate, etc., were controlled accurately. The results indicate that with a regular acid fixing and hardening bath (F-25) there is no advantage, but rather a disadvantage in washing at the isoelectric point (ca. pH 4.9) rather than at pH 7 to 8, since the time required to remove hypo to the same degree is increased, nor is less water retained. In a non-hardening acid fixing bath, there was little difference in washing time, but some gain in drying time for the isoelectric wash because of reduced water absorption.

Print ISSN

0097-5834

Published

1938-07

Content type

Original Research

DOI

10.5594/J14655