Ink impression of ‘Le Cardinal d’Amboise’ taken from a heliographic plate, made by Joseph Nicéphore Niépce in 1826.
This impression was made by Niépce from a plate of ‘Le Cardinal d’Amboise’, held today at the Musée Nicéphore Niépce, Ville de Chalon-sur-Saône.
The original plate from which the impression was taken was created using Niépce’s Heliographic process, using Bitumen of Judea on a metal plate, which hardens when exposed to light. An engraving was varnished, placed over the plate and exposed to sunlight. The soluble unexposed bitumen was dissolved in an oil of lavender-kerosene mixture and the plate was etched in an acid bath. The exposed hardened bitumen acted as a resist, so that the acid etched only areas of unexposed metal. The resulting heliographic plate was used to make final prints on paper.