photogravure

Photogravure is an intaglio printing process that produces continuous-tone images by etching a copper plate to hold ink in recessed areas and transferring it to damp paper under high pressure. The tonal range is achieved by a finely modulated relief rather than discrete lines, allowing photographs and artworks to reproduce with smooth gradations.

The technique developed in the 19th century to improve photographic reproduction and reached prominence in the late 1800s and early 1900s in art books, portfolios, and magazines. It remained valued for its ability to convey subtle texture and depth, and it is still practiced by specialized printers today.

Process: A copper plate is cleaned and coated with a light-sensitive film, typically gelatin or a photopolymer. The coating is exposed through a negative to create a tonal image, then developed. The plate is etched in an acid bath to bite the unexposed areas, with aquatint or other controls to adjust density. After etching, the coating is removed, the plate is inked and wiped so ink remains only in the recesses, and damp paper is run over the plate in a press to transfer the image.

Materials and variants: Traditional photogravure uses copper with gelatin- or bitumen-based coatings; modern variants include photopolymer gravure that eliminates some chemical steps. The process is skilled and time-consuming, but yields rich, stable images with long print runs.

Applications and significance: Photogravure is used for fine art prints, limited editions, and high-quality book illustrations. It remains an important technique in contemporary printmaking for its depth, warmth, and tonal range, even as digital methods have grown.