2. The Heliographic Engravings of Niepce de Saint-Victor (1805-1870)

Claude Félix Abel Niepce de Saint-Victor was the son of the first cousin of Nicéphore Niépce. He became famous in photography for having developed the first photographic technique on glass where all previous techniques on paper, the calotype for example, produced an intermediate negative.
He did all kinds of research, on producing colour photographs, on reproducing engravings and drawings via iodine vapours and on heliographic engraving made from images made using asphalt.

He did all kinds of research, on producing colour photographs, on reproducing engravings and drawings via iodine vapours and on heliographic engraving made from images made using asphalt. Niepce de Saint-Victor was only interested in making images engraved on metal and did not work with Nicéphore's iodine inversion technique. The changes he introduced to heliography had to do with the composition of the varnish, the solvent used to make the image appear, the technique used to spread the solvent and the techniques used to engrave. The varnish that he used was composed of 90 parts of benzene, 10 parts of essential oil of lemon and two parts of asphalt. The solvent he used was composed of five parts of oil of naphtha to one part benzene. The varnish was very diluted in a very volatile solvent. The layer of asphalt obtained was consequently so thin that it displayed iridescence like a film of oil on the surface of water. As a result exposure time was decreased because the thickness of the asphalt that was to become insoluble was slight. Another consequence was the capacity of the acid to etch the metal across the layer of asphalt, which had increased compactness the more light it received.

With such a fine layer of varnish, it becomes difficult to reproduce a large range of shades, contrary to the procedure that Nicéphore Niépce used. For the procedure we are describing here, this inability to reproduce shades through varying the thickness of the varnish was not considered a difficulty. This is due to the fact that, in photoengraving, gradation in shading is accomplished by varying the density of the grains, each of which can have the same thickness of varnish.
The sensitivity of a varnish is a function of its thickness. The thinner it is the better. Using the varnish of Niepce de Saint-Victor, only 10 minutes of exposition of a glass plate to direct sunlight were needed to obtain a result, whereas 2 to 3 hours of exposure were necessary for an engraving made with translucent paper. Both these times were much lower than those for Nicéphore Niépce's heliographs.

Niepce de Saint-Victor also discovered how to presensitize asphalt. By exposing asphalt in powdered or dissolved form to sunlight and air for a few hours, he increased its sensitivity. In Nicéphore Niépce's method, presensitizing was done when heat was applied to dry the varnish, a process that Niepce de Saint-Victor did not use. He seemed not to have observed the ageing of asphalt solutions in the absence of light, which, after a few days or even a few weeks, makes them more and more sensitive.

We have a few printed documents that reproduce drawings or photographs made using the technique perfected by Niepce de Saint-Victor. I have been able to see several prints made with this process, made by Pauline Riffaut and finished by the engraver A. Riffaut. One is a portrait of the Empress Eugdnie, one of Napoleon III and one of Niepce de Saint-Victor himself. There are some zoological plates' printed in 1853 in the book Photographie Zoologique by Rousseau and Devéria.







"Photographie Zoologique"
by Rousseau and Devéria, 1853

Examination under a printer's glass clearly shows that Niepce de Saint-Victor's were unusable in the form they took after the action of the acid. In fact, they served as a Ode for the engraver who, after the acid bite, executed the engraving by hand by following the forms and shadings that had been cut into the surface. Only the background of the image was not retouched. It was made of an aquatint grain either obtained through traditional nitric-acid engraving methods or by acid applied to a very thin layer of varnish that had been largely dissolved. Accounts at the time of Niepce de Saint-Victor confirm the fact that the images lacked halftone effects and it is worthy of mention that the images that were published were always retouched by an engraver.

Niepce de Saint-Victor's use of asphalt was special and unique in the history of photomechanical methods. What he did was to try to obtain a halftone engraving through asphalt varnish known for its exceptional impermeability to acids. We will see that, in the other techniques developed after Niepce de Saint-Victor, the varnish was always used either as a screen to the acids or as insulation against electroplate metal deposits.

Niepce de Saint-Victor's method did not last for very long, in particular because it always required the intervention of an engraver. Its merit was that it was a pioneering method and opened the way to newer methods. In his study of the heliographic techniques of C. Nègre, J. Borcoman writes: "The method used by Niepce de Saint-Victor was successful in reproducing line engravings, but when it is applied to images with grey shading the results are extremely rudimentary. All the shading prints as deep black independently of their diverse densities in the photograph. Since it is incapable of reproducing the subtle rage of halftones, it is this method that Nègre set himself to perfecting".