From Greek helios (sun) and graphein (write), also called photogravure. A printing process that uses a gravure printing plate with a photographically prepared surface. Based on a template, a slide is made by using light-sensitive gelatin paper. The slide is then pressed on a copper plate covered with asphalt dust. After drying, the plate is cauterised in iron chloride. The recesses on the plate absorb the ink during printing. By pressing the plate on moistened paper, the ink is transferred onto the paper. Heliogravure is characterised by its warm and soft hues and the impressions of the plate left on the paper.