When the Daguerreotype was announced on 19 August 1839 at the Académie des Sciences, the Heliography process was also described by Arago. The way in which he presented Niépce's method was done in terms so negative that nobody accorded any importance to asphalt-based heliography. Everybody was infatuated with the daguerreotype, a technique that made the portrait available to everyone.
Nevertheless, although the daguerreotype was universally praised, it was reproached for being a technique that produced a single image. Certain people tried to transform the daguerreotype into an engraved plate that could be used for making printed reproductions of the image. A number of techniques were developed, but they were never applied on any extensive scale since they were very complicated and unreliable.





Engraved plate made from a daguerreotype
When the daguerreotype was replaced by Talbot's calotype, it was believed that this technique could easily be used to illustrate books. The images were obtained on paper and by simply making copies from the negative by contact printing. There was no need for intermediate optical procedures. The method used by Talbot and by Blanquart-Evrard consisted of hand gluing the photographs into the books.

It was slow work and what is worse, the photographs aged badly and slowly deteriorated. It became clear that a way to print photographs permanently had to be found.


Original cover of
"Pencil of Nature" by H.F Talbot


Niepce de St Victor

It was at that point that Nicéphore Niépce's technique for obtaining engraved plates was resuscitated. There was an attempt to use it to reproduce not only drawings but photographs on translucent paper or on glass. Meanwhile, the glass negative replaced the paper negative, thanks to Niepce de Saint-Victor's invention.






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Until then shading on photoengraved images was exclusively done by more or less tight crosshatching. It is well known that when continuous shading is engraved, the metal must be grained to hold the ink, or else it will be lost when the plate is pressed. The various techniques developed after Nicéphore Niépce's death resolved the problem in one fashion or another. In what follows, we will limit ourselves to citing only the principal photomechanical methods developed after his death that used asphalt as photosensitive product.
We will intentionally not touch upon those procedures that use the same principle as Niépce's but depend on the use of bichromate colloids (albumin, gelatine gum)..