Photographic techniques can also be employed with etching. In photoetching the ground is a plastic material and a halftone screen is usually used. In photogravure, the process used at Crown Point Press, the acid-resistant ground is a photosensitized gelatin layer that is dissolved in the areas of the metal plate eaten away by the acid. An aquatint provides the tooth, substituting for a halftone screen so the photograph’s different tones can be captured.
Direct gravure is a similar process, but no photograph is used. The artist draws an image on Mylar, and that image is directly transferred to the photosensitized gelatin by shining light through it. Aquatint is used to provide tooth, and the tones of the drawing are etched into the plates in varying depths, just as they are in conventional aquatint processes.