“The screen plate devised by the Frenchman Louis Dufay was made by superimposing a screen of pairs of lines of complementary colours, such as magenta and green, at right angles on a screen of pairs of lines of non-complementary colour, such as cyan and yellow. The combination produced green lines with rows of red and green squares between them. Dufay claimed four colours on his screen, since the combinations of green and cyan and green and yellow produced slightly different hues, but this made no difference in practice. The screen had 150 to 200 elements to the inch (60 to 80 to the cm). The process was first named Diopticolore, when it was announced in the summer of 1908 (at that time the screen was being produced by a greasy ink printing method, like Omnicolore), but the ‘four-colour’ screen process was launched in Spring 1909 under the name Dioptichrome.

The screen was mounted in a nickel frame, into which the special ‘Panchro-Inversable’ plate was located with centring springs. The frame was fitted into the plate-holder, and exposure made in the usual way through the screen. The exposed plate was processed by reversal development, and was returned to the frame for viewing. In the summer of 1910, a new version with an integral screen coated with emulsion was introduced, and around 1912 the method of manufacturing the screen was changed to produce a screen with blue lines alternating with rows of lozenge-shaped red and green elements.

For an average subject in bright sunshine the Dioptichrome plate required an exposure of one second at f/11. The screen transmitted 21% of the light falling on it a great improvement over the 7 ½ % of the Autochrome plate. H. Essenhigh Corke, a leading colour worker, said, ‘on the score of brilliance and transparency the Dioptichrome is a very great advance upon the Autochrome’. While the quality and saturation of colour were good, the Dioptichrome plates were often defective, with pinholes which produced green stains around each spot. They were on the market until the First World War, after which they were replaced by the Dufay Versicolor screen plate, first described in 1917 and using an alternative method of production by which the screen was formed by a technique involving grooving a celluloid sheet by embossed rollers.”

(Coe, Brian (1978): Colour Photography. The First Hundred Years 1840-1940. London: Ash & Grant, pp. 59-60.)

“The next Frenchman to enter the field was Louis Dufay, who obtained two patents in 1908. According to the second of these two specifications, a gelatine-coated plate (or film) was sensitized with bichromate and exposed through a line screen before being rolled-up with a layer of opaque greasy ink which adhered only to the hardened areas. The spaces between the ink lines were then dyed red. Next, the whole surface of the plate was coated with a layer of varnish that adhered to and protected the dyed area, but elsewhere could be dissolved and removed together with the underlying greasy ink. Then a new set of greasy ink lines was applied at right-angles to the first set and the unprotected areas between the resist were dyed blue-violet, before the plate was again coated with varnish. By now, one third of the surface of the plate was coloured red and one third blue-violet in the form of alternating rectangles. Finally, the layer of varnish was dissolved together with the greasy ink so that the intervening lines could be dyed green, to complete the mosaic.

Dufay enlisted the co-operation of the Guilleminot company to produce his plates which were sold under the name Dioptichrome. For a while, Dioptichrome plates were offered either pre-coated or as taking screens to be used with separate panchromatic plates. The taking screens were supplied in metal frames which could be used again to combine a positive plate with the screen for viewing the finished colour transparency. There were advantages in using screen plates with some form of regular geometric pattern. On the one hand, if produced accurately enough, they allowed the use of separate taking and viewing screens, which made for easy duplication. Also, the whole of the surface of the plate was covered by filter elements with no intervening spaces to be filled in with carbon black as had to be done with the starch grains of an Autochrome plate. Consequently, it was estimated that a Dufay Dioptichrome plate would transmit some 20% of the light reaching it while an Autochrome plate would only pass about 7 1/2% of incident light. Another advantage of regular over random filter elements is the avoidance of the clumping of elements of the same colour that occurs in the latter, giving them a much more mottled appearance. These advantages of using a geometric pattern of filter elements rather than randomly dispersed starch grains, with their unavoidable interstices, must have tempted the Lumieres to consider a change of direction, because in 1908 they patented a method of producing a screen which Louis Dufay considered he had anticipated in his earlier patent. Correspondence exists which indicates that Louis Lumiere acknowledged Dufay’s priority.”

(Coote, Jack H. (1993): The Illustrated History of Colour Photography. Surbiton, Surrey: Fountain Press, on pp. 44–45.)

“The most successful of all the screen processes was the one initiated by Louis Dufay. Today the product is known as Dufaycolor, but it was first introduced about 1910 as the Dioptichrome plate. The first Dufay patents were assigned to an organization carrying the quaint name “A Company for the Exploitation of the Process in Color Photography of L. Dufay.” This became the Versicolor organization. Some time later Spicers Limited became interested and such companies as Spicers-Dufay, Ltd., Dufaycolor, Ltd., and Dufay-Chromex, Ltd., were formed to exploit the disclosures. Finally the Ilford company became interested. In the United States there was but one organization, Dufaycolor, which marketed the product.

The first Dufay disclosures (Eng. P. 11698/08; Ger. P. 237755; U.S.P. 1003720) were concerning the preparation of the Dioptichrome plate, which combined dichromate printing and transfer a la wash-off-relief, for the formation of the screen. A variation of this was contained in English patent 18744/08.”

(Friedman, Joseph Solomon (1945): History of Color Photography. Boston: The American Photographic Publishing Company, on p. 166.)

“Although it did not always bear Dufay’s name, the process he invented in 1907 was pursued in modified forms and under various names for over forty years – covering much the same period as the Autochrome process.

Louis Dufay, son of the notary in the small town of Baume les Dames near Besançon, was born in 1874. After studying law and working in a practice in Chaumont, he somehow became interested in colour photography and then conceived, and in 1907 patented, a method for producing a geometric filter réseau for a screen-plate.

In his patent, Dufay described this procedure at some length.

Briefly, a transparent support, having been coated with a thin layer of gelatine, was covered by a pattern of parallel greasy ink lines to serve as a temporary resist. The gelatine between the ink lines was then dyed red. The surface of the plate was then coated with a varnish that adhered to and protected the dyed areas but elsewhere could be dissolved and removed together with the underlying greasy ink. Next, a new set of greasy ink lines were printed at right-angles to the first and the unprotected areas between the resist dyed blue-violet. The whole surface was again varnished and the resist removed. By now one third of the surface was coloured red and one third blue-violet in the form of alternating rectangles, while the remaining third of the area, represented by parallel lines, was dyed green to complete the mosaic.

This may seem to be a very complicated way of forming a mosaic of red, green and blue filters, and in fact the method was simplified later, when Dufaycolor was produced on film-base.

There is evidence that in 1908 Dufay tried to interest Lumière in his patent, but by then that company was probably quite happy with their method of producing a random screen pattern. He had more luck with Guilleminot, a plate and paper manufacturer with a factory at Chantilly, where Dufay and his family went to live in 1909.

A company name la Société des Plaques et Produits Dufay was formed with a capital of 420,000 Frs. and the plates were called Dioptichrome. They were on sale for only a few years, the most successful of which was 1911, when 40,000 plates were sold.

Because there were no gaps to fill between the filter elements as there were with the dyed starch grains of an Autochrome, Dufay Dioptichrome plates were faster and the results more transparent than the Lumière product. But the resolution of an Autochrome was far superior to a Dioptichrome transparency because the filter réseau of the latter only contained about 40,000 elements to the square inch compared with the millions of starch grains covering each square inch of an Autochrome.

However, things did not go smoothly and there were many difficulties and disputes, so that by 1914 the company was dissolved – possibly because the war made it impossible to continue. After the war, Dufay renewed his efforts to promote his process, this time concentrating on production of film rather than glass-based products, no doubt with cinematography in mind.”

(Coote, Jack H. (1993): The Illustrated History of Colour Photography. Surbiton, Surrey: Fountain Press, on pp. 47–49.)

“Dioptichrome

In 1907 the French lawyer Louis Dufay (1874-1936) patented a system whose screen pattern was obtained by the combined use of dichromated colloids, greasy printing inks, and imbibition.¹⁶ To take a photograph, the screen was mounted in a metallic frame into which a panchromatic plate was inserted before exposure in the camera. The photographic plate was processed individually and returned to the frame for viewing (Fig. 2.11). To form the screens colored pattern, a plate coated with dichromated gelatin was printed through a screen with parallel opaque lines. After a wash to eliminate the dichromate, the plate was immersed in a red dye. The soft gelatin absorbed the color in the parts that were left unexposed under the screen. The plate was then covered with a black greasy ink that did not adhere to the red lines. It was placed in contact with a plain gelatin-coated plate (the receiving plate) that took in the greasy ink and the red dyes, which were transferred by imbibition. The receiving plate was then varnished overall. When both ink and varnish were dry, a solvent was applied to dissolve the greasy ink. The solvent did not affect the varnish, but as the greasy ink was dissolved portions of the varnish coated over it were also removed, leaving the receiving plate with parallel red lines protected by a varnish. A second dichromated gelatin plate was printed through the screen. It was immersed in a blue dye bath, coated with black greasy ink, and applied onto the receiving plate at a right angle to the red lines. After the greasy ink was removed from the receiving plate, a third dichromated gelatin plate saturated with green was applied to its surface. The varnish was then completely removed, leaving a homogeneous screen whose regular pattern consisted of approximately 150 to 200 red, green, and blue elements per square inch (BJP 1918) (Fig. 2.12). First named Diopticolore when it was announced in 1908, the product was launched in spring 1909 under the name Dioptichrome.¹⁷ The plates were manufactured by Guilleminot, Boespflug et Compagnie of Paris and marketed by the Société des plaques et produits Dufay. In 1910 a combined screen version of the Dioptichrome was introduced and marketed under the name Dioptichrome-B (Dobrusskin 1998: 65). Around 1912 the method of manufacturing the screen was changed to produce continuous blue lines alternating with rows of lozenge-shaped red and green elements (Fig. 2.13). Although Dioptichrome had good color rendition and was five to six times faster than the Lumière autochrome (Coote 1993: 44), plates were often defective, with small pinholes that produced green stains around each spot (Coe 1978: 60). It remained on the market until the onset of World War I, when the society was dissolved.”

Notes

¹⁶ English Patents 11,698 and 18,744 (1908).

¹⁷ It was also referred to as Dufay screen plate in the press.

Bibliography

British Journal of Photography (BJP). 1918. “Processes of Making Colour Screen-Plates.” British Journal of Photography Monthly Supplement on Colour Photography (May 3): 18–20.

Coe, Brian. 1978. Colour Photography: The First Hundred Years, 1840-1940. London: Ash & Grant.

Coote, Jack H. 1993. The Illustrated History of Colour Photography. Surrey, U.K.: Fountain Press.

Dobrusskin, Sebastian. 1998. “Fotografische Farbstoffrasterverfahren: Prinzip, Technologie und Identifizierung.” In Farbfehler! Gegen das Verschwinden der Farbfotografien, 53–78. Rundbrief Fotografie, Special Issue 5. Goppingen: Museumsverband Baden-Württemberg.”

(Pénichon, Sylvie (2013): Twentieth Century Colour Photographs. The Complete Guide to Processes, Identification & Preservation. London, Los Angeles: Thames & Hudson, on pp. 31–33.)

“Dufay Dioptichrome Screen (1909-1910): continuous lines of green color (approximate width 0.06 mm) between which are rectangles of alternating red (0.07 x 0.1 mm) and blue (0.065 x 0.09 mm) color (Fig. 2.51). Lines are perpendicular to the edges of the plate. The blue rectangles have a black outline and are slightly smaller than the red ones. Existing plates are dominantly purple. Channeling of the screen and cracks in the gelatin emulsion are common deteriorations.”

(Pénichon, Sylvie (2013): Twentieth Century Colour Photographs. The Complete Guide to Processes, Identification & Preservation. London, Los Angeles: Thames & Hudson, on pp. 66–68.)

“Dufay Dioptichrome-B Plate (1910-1912): screen pattern identical to that of the viewing screen from the Dioptichrome separate system (Fig. 2.59). There are continuous lines of green color (approximate width 0.06 mm) in between which are squares of alternating red (0.07 x 0.1 mm) and blue (0.065 x 0.9 mm) color. Lines are perpendicular to the edges of the plate. The blue rectangles have a black outline and are slightly smaller than the red ones. Fading of the dyes is common and existing plates are dominantly purple. Channeling of the screen and cracks in the gelatin emulsion are common.

Dufay Improved Dioptichrome-B Plate (1912-1914): new methods of production resulted in a slightly different screen pattern than in previous Dioptichrome materials (Fig. 2.60). The blue lines are at a 45-degree angle from the edge of the plate; all the elements have a black outline.”

(Pénichon, Sylvie (2013): Twentieth Century Colour Photographs. The Complete Guide to Processes, Identification & Preservation. London, Los Angeles: Thames & Hudson, on pp. 71–72.)