Collotype

[Sarah]

A photomechanical print made directly from a hardened film ofgelatin or other colloid; also, the process of making such prints.According to one method, the film is sensitized with potassiumdichromate and exposed to light under a reversed negative. After thedichromate has been washed out, the film is soaked in glycerin andwater. As this treatment causes swelling in those parts of the filmwhich have been acted on by light, a plate results from whichimpressions can be taken with prepared ink. The albertype, phototype,and heliotype are collotypes.