An ink printing process in which a glass printing plate is coated with bichromated gelatin, dried, contact printed with a negative and then washed; leaving a positive image formed by the light-hardened gelatin. A dilution of glycerin and water is applied to the surface and absorbed into the areas of less hardened gelatin. As in lithographic printing, when inked, the ink repelled from those areas where water has been absorbed, leaving a positive ink image on the hardened gelatin. Collotype also called Albertype, Artotype, Autotype, bromoil, Dallastype, Heliotype, Levytype, Paynetype, phototype, photoglyphic is the most accurate and beautiful method of photomechanical reproduction yet invented. Collotype can produce results difficult to distinguish from actual photographs, many old postcards are collotypes.