Polymetaal

A technical dictionary of printmaking, André Béguin.

ln his " Essai sur l'histoire de la gravure sur bois" ( Paris, 1863)/\mbroise Firmin-Didot wrote that "photography, this new marvel which allows us to reproduce objects as quickly as electricity shortens distances, might well replace wood engraving were it not hat the use of chemical processes seems to pose insurmountable problems, at least insofar as concerns the economic side of things." ln fact, in 1863, wood engraving was the only technique that could be used in typography since the developments of photography did not yet allow anything more than the transferring of an image onto a wood block, thus simplifying the work of the engraver. Photochemical techniques such as photo-engraving were not yet invented.
Today, however, this technique (either as a relief or an intaglio technique ) has become fully automatized in the rnost modern workshops.
ln 1855, photolithography had already been invented and was already beginning to be applied to metal plate lithography [photographic techniques ]. However, these techniques were used above all for reproducing images rather than pages of text and could only be inserted in books rather than being printed directly. It was not until relief metal plates were made that printers could print simultaneously both the image and the text of a book.
As of 1826 Niepce had managed to work out the principles of making engravings with photographic methods and had actually used the process for a portrait of the Cardinal d'Amboise. This portrait may well be considered the first photo-engraving. ln 1850 F.Gillot invented and began to use a process that he called paniconugraphie. This process, which consisted in transferring a line drawing from a litho stone onto a zinc plate, gave as a result a typographical zinc plate bearing an image. Gillot also developped a particular kind of etching that is still used in photo-engraving: successive bitings and stopping out procedures carried out with a rather soft ink that flows down the slope* of the etched lines. This kind of stopping out protects the lines from horizontal etching. Asphaltum powder is applied over and above the ink in order to reinforce the stopped out areas [* ink ]. The ulterior deepening of the lines had to be carried out to permit typographical* inking of the plate.
Only in 1872 did Gillot adapt his process (that had come to be known as the Gillotype* process) to photography, but even then only line drawings could be reproduced.
The experirnents of A.Poitevin should also be mentioned here. As of 1845 Poitevin made moulds from relief gelatine plates. The moulds were then used to make relief blocks. A similar process was invented and used by J.Moss of New York between 1875 and 1880.
What was still missing was a process that could reproduce half tones. On relief plates this was an impossible task when using the traditional methods of hatching or dotted surfaces. lt was not until the invention of the screen that the problem was resolved. The screen system was invented by Meisenbach in 1882 and later perfected by lves who introduced the square ruled screen with a square diaphragm in 1886. The glue enarnei process of H.W.Hislop, also invented in 1886, allowed for the first applications of the lves system.
ln the beginning, photo-engraving was also called heliogravure. In France this term led to a certain amount of confusion since it was also used for grained photogrqvure which was practiced as of 1852 ( F.Tall›ot, .l.5wan, K.K|ic ) and for screened photngravure after 1893 (K.Klic ).
Today photo-engraving is perfectly adapted to the various printing processes: typography, photogravure, and offset. However, it must be born in mind that the way of making the plates is different since each printing technique requires a particular plate.
Typographical photo-engraving consists in making zinc relief plates (because of this it was, at times, called zincography*) which are then mounted on a wood block so that the image will be just as high as the letters to be printed. The line cut or photo line engraving is, as the term suggests, a block for images that are only made ol lines and in which there are no half tones. ln fact, half tones can only be reproduced with the halftone process which uses a screen. Colour images are made with the help of three or four different plates [* three colour process ].
Electronic photo-engraving is a photomechanical process which requires no etching. This system entails direct burning, carried out with the help of a photoelectrical cell which "reads" the original (a drawing or a photograph ). This kind of photo-engraving is done on metal or plastic plates and produces a typographical relief plate.[* gillotype ].