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photogelatin process[¦fōd·ō′jel·ət·ən ‚prä·səs]
Photomechanical process for producing prints directly from a hardened colloid film; the sensitized film is exposed under a reversed negative, desensitized, and then soaked in glycerin and salt water so that the parts that have not been exposed to light undergo swelling; the swelled parts are ink-repellent and the unswelled parts ink-receptive, thereby forming a printing surface of the lithographic sort. Also known as collotype.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.