Engraving done using photochemistry.
A process for making relief plates by using acid to etch away the non-printing areas of a photographically produced image. The subject is photographed through a wire or glass screen, which breaks the light in a way that sensitizes the metal plate in a dotted pattern. Darker areas are created with larger dots while highlights are rendered with finer dots. When printed, the finest screens create the most precise detail. This process was used principally for reproducing illustrations in the earlier part of the 20th century.
an engraving used to reproduce an illustration
In letterpress, the process of creating a relief plate photochemically.
Making printing plates by exposure of line and halftone negatives on sensitized metal, converting the image into an acid resist, and etching the print to the relief required for letterpress printing.
Letterpress printing plate.
Photo-mechanically produced metal relief printing plate used for letterpress printing.
A photographic process of preparing plates in relief for letterpress printing.
Photoengraving also known as photo-chemical milling is a process of engraving using photographic techniques. The most common type of photoengraving involves using a material that is photosensitive and resistant to acids or other etching compounds. This material, called a photoresist, is applied to a metal to be engraved.