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Tricolor and Process Printing


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COLOR FILM


By the later half of the 19th century the possibilities of producing color photographs had long been discussed but no practical results were seen. The many attempts to invent color film in the early decades of the 20th century had met with only marginal success. These years saw the invention of Autochromes, Dufaycolor, Finlay Color, Colorol, and many lesser known processes that were only on the market for a few years, and while they all rendered acceptable colors in relation to the original subject, none could be said to accurately capture natural color. When measured against black & white film these color processes were a marvel, but the massive internal structure needed to hold their dyes in place created a very noticeable grain and required excessive light to use. In general all these films had to balance color saturation against brightness, which resulted in images that were somewhat grey. Many of these early photographs looked closer to being hand colored than to what we would recognize as color photography today. The various theories they were based on were sound, but the mechanics of a workable model would prove evasive until the 1930’s. when Kodachrome and Agfa Neu were introduced.

While early color photographs left much to be desired, they were still used for about thirty years as the starting point for much printed material. Even if the color was poor, they offered a more realistic foundation for determining the dispersal of color than the eye of the retoucher ever could. Postcards based on these processes do not generally make any reference to them so matching cards to a particular film cannot be made with any certainty. The color scheme on a postcard may hint at a particular film type, but even if printed with fidelity there is no guaranty of a match. Trade names are also no assurance that they were made from the film they reference since the name could only allude to a similar look. Despite the great array of films available, most photographers worked with the less expensive black & white variety and it was these photographs that most color postcards continued to be printed from with the aid of retouchers.



Joly Process
One of the earliest tricolor processes was proposed by Ducos du Hauron. He believed that a screen made up of fine evenly dispersed red, yellow, and blue lines would render an optical grey when viewed from the proper distance, so the removal of select lines would throw off this balance and create a color image. Though he received a patent for this idea in 1868, nothing was actually made from it until the Irish professor John Joly began studying these principals. With a ruling machine Joly drew precisely spaced red, green, and blue-violet lines of aniline dye onto a gelatin coated glass plate and then varnished it. This screened filter was then placed in direct contact with the emulsion of a photosensitive glass plate before exposure. Another line screen with an identical pattern was then carefully aligned over the developed transparency and sandwiched together they would form a color image. The Joly Process went on the market in 1895, one year after its patent but the poor color sensitivity of most film yielded inadequate results. These same principals however would be expanded upon with great variety during the early 1900’s.

Autochromes
While early tricolor printing could in theory create the look of a color photograph with full tonal range, there were obstacles in the way of its practice. The most obvious problem was that there was no accurate fine grain color film to base an image on. The choice was to revert back to filtered black & white panchromatic negatives or separate hues from one of the new experimental methods of color photography. The most popular early photographic film was Autochrome that create a one of a kind color transparency on a glass plate. Autochromes were patented in 1903, and manufactured from 1907 to 1935 in France by the Lumière brothers. This was the first practical, and one of the few commercial means of creating color photographs during their early years of production.

Autochromes are made by coating a glass plate with a layer of dyed potato starch granules that approximated the primary additive colors of red, green, and blue. After shellac is applied and dried, the plate is coated with a panchromatic silver gelatin-bromide emulsion. When the plate is exposed, the dyed grains of starch acts as tiny RGB filters before light reaches the silver emulsion. When the plate is developed a negative image is created. Afterwards the silver is bleached out and the plate re-exposed and redeveloped using an acid dichromate process. The result is a one of a kind positive transparency in full color. These transparencies were often viewed though Magic Lanterns or specially designed hand viewers called Diascopes, which were boxes that held the glass plate while the image was projected onto a mirror.

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Autochrome Screen: While Autochrome plates already had an irregular pattern, their dyed particles of starch tended to clump resulting in an uneven mixture of color. This in turn created a coarse looking grain on the final transparency. The spaces between each particle were filled in with an opaque black, which slowed down exposure time.


Autochromes could not capture all nuances of color but they did produce subtle tonalities. Their colors also lack luminosity for the supporting matrix wasnít a continuous transparency but more like a screen with the space between each starchy grain dyed an opaque black. When an individual color needed to be highlighted the other colors within that particular area would be darkened reducing the brightness of the transparency even further. Its strange grainy effects aggravated by the clumping of the starch tended to yield an image that appeared to be halfway between a painting and modern photograph. The exposure time for Autochrome plates was very slow, about 2 seconds in sunlight, up to 30 seconds in a studio, and they cost more than ten times their black & white counterparts. While these features put limits on their use, millions of images were still made from them. There is little to no documentation on the photographs most postcards were made from but the appearances of many reflect the same qualities found in Autochromes.

Postcard

Tricolor Print: This German postcard from 1908 is rare in that it attributes its natural appearance to its Autochrome origins. While it does have a more natural appearance than most cards of its time, the color fields remain relatively flat due to retouching and the manner in which it was printed. The green dyes in the film have been replaced with yellow ink on the card. In the detail below we can see that the RYB halftone dots have all been printed in a 45-degree rotation, with the blue forming long lines. A black halftone has been added at a 90-degree angle, but it serves as a color and not as a key plate, which keeps all the hues brighter.


Illustration

The Autochrome emulsion was moved from glass plates to film in 1932 when the Lumière brothers created Lumicolor. It was soon replaced by the even faster Filmcolor in 1938 that used brewers yeast in place of potato starch. The last version, Alticolor was introduced in the early 1950’s but it couldn’t compete with more advanced multi-layered film and was discontinued by 1955.

Postcard

Tricolor Print: The photographer Hans Hildenbrand began using Autochrome in 1909, and by 1911 he was using these transparencies to print tricolor postcards. He used a red, yellow, and dark blue pallet to create cards that closely resembled the original autochromes. Hildenbrand was the only official German war photographer that had his images published as postcards in natural color during World War One.


Postcard

Tricolor Plus: The Swiss postcard above from 1913 is based on a photograph by Richard Worsching. While it uses a typical tricolor palette of red, yellow, and blue, it also includes an untypical extra light blue. This extended palette may be similar to that used on linen cards, but the results are something closer to a modern photochrome. Even without proper process colors to work with, some printers could still extract a great deal from an Autochrome.


Finlay Screens
In 1906, Clare L. Finlay patented filters for use in color photography, and they went into production two years later as Thames Screen Plates. This was not film but a block out filtering screen containing a mosaic of alternating red and green circles on a blue background, which would be placed directly over a panchromatic photo plate before exposure. Its thinness allowed for exposures that were eight times faster than Autochrome. The exposed plate could be either be reversed through processing into a positive transparency or re-exposed to a positive plate. The final product would then be carefully registered with a Thames Viewing Screen that provided the color, and then they were sealed together.

Many similar screens for glass plates were manufactured about the same time such as Aurora, Veracolor, Paget, and Leto but they all met with little commercial success. In the years immediately following the First World War they generally became prohibitively expensive to use. The Thames Plates were discontinued in 1910 but a new pattern to be used in conjunction with much more sensitive plates came out in 1929 as the Finlay Color Process. Each color took the form of a rigid square almost twice the size of his previous circles. This process was used throughout the 1930ís with a brief revival in 1953 as Johnson’s Colour Screen.

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Finlay Screens: Above is a pattern from a Thames Screen Plate. Each circle was 1/400 of an inch wide. Below is the pattern found on a screen from the Finlay Color Process with squares of about 240 per square inch.

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Dufay Screens
Dioptichrome, patented by Louis Dufay as Diopticolore in 1908 and made public a year later worked on the same additive color principals as the autochrome. Here alternating lines of magenta and green were overprinted with lines of yellow and cyan. While this should have created four different colors, the yellow green and blue green were largely indistinguishable from each other. In 1910 the pattern was improved upon but the defects that rendered poor color remained constant and manufacturing ceased by World War One.

Illustration

Dufaycolor Screen: Here we can see the very rigid pattern used on Dufaycolor film. While popular when first introduced, the use of all such screened processes disappeared from the market by the 1950’s.


With Dufaycolor a collodion film is dyed blue then overprinted with a thin layer of green squares and red lines in translucent ink on a rotary press. After a series of bleaching and dying steps the screen was varnished and coated with a panchromatic emulsion. The emulsion could only be exposed to the single hue that corresponded to the pattern of the color grid (reseau) laid across its surface. The exposed negative could then be color separated by projecting it back through color filters. Printing plates made by this process were usually printed in gravure. Dufaycolor began being manufactured in 1931 as 35mm motion picture film and it became available for still photography in 1935. Dufaycolor was easy to develop and its speed was only about a third of black & white film, which helped to keep it popular into the 1950’s. Agfa Ultra, introduced in 1932 was a similar type of film.

Advertisement

Dufaycolor Film Ad: “If you want to take pictures as you actually see them - in natural color - load your camera with Dufaycolor film and shoot.” It was further promoted as capturing the most subtle tones, and for its ease of use without the need for special cameras or filters. The difficulty of traditional color photography was clearly on the public’s mind, and ads had to overcome this fear.


Agfa Color Plate
In 1908 J.H. Christensen patented a screen plate where an emulsion made up of red, green, and blue dyed resin particles would be poured over a varnished glass plate. As the droplets stuck to the plate’s tacky surface, an irregular color pattern would form. With all colors in direct contact with each other there was no need to add opaque fillers that cut down on light transmission as on Autochromes. German Agfa acquired Christensen’s patent and began experimenting with it in 1912. It was introduced to the market in 1916 as Agfa Color Plates, but because of the World War it was not distributed beyond Germany until the early 1920’s. While its speed and grain were slightly better than that of Autochromes, and its qualities were improved on over time, it was never as popular with photographers. A very similar high quality screen called Lignose Natural Color Film came out in 1926.

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Dufaycolor Screen: While Agfa Color Plates provided a random grain without the need for opaque fillers, its color particles still tended to clump together resulting in a coarse look on the final transparency.


Carbro Color
In the 19th century the search for durable photographic prints that were not dependent on dyes led to a pigment based process known as Carbon-Printing. This was expanded upon in 1889 by Howard Farmer who discovered that dichromate gelatin emulsions could harden without exposure to light when it was placed in contact to fine particles of silver. Thomas Manly used these principals to patent the Ozobrome Process in 1905. This process involves a strange chemistry in which a photo sensitized carbon (carbro) tissue is applied to a wet gelatin silver bromide photograph with a squeegee. The gelatin on the tissue will harden in proportion to the amount of silver that transfers onto it from the bromide print. After the photograph and the tissue are separated, the tissue is laid upon a sheet of transfer paper, and when separated again it will leave the gelatin layer attached to the transfer paper. The excess gelatin is then washed away leaving behind a carbon based image in the remaining gelatin, which is then hardened in an alum bath. Tricolor carbro photographs can be made by transferring images from three separate silver bromide prints whose images were first shot through a red, green, and blue filter onto three sheets of carbro tissue, each pigmented in relation to the color filters used. The gelatin from all three tissues would then be transferred onto a single sheet of paper to create a color photograph.

The Ozobrome or Carbro Process received its first commercial application in 1913 when pre-dyed tissue was sold under the Raydex name. While this was an elaborate process, it was used by professional and amateur alike because there was just no other means available at this time to create color photographs on paper. Carbon tissue could be infused with any pigment that was desired. Unfortunately many unstable pigments were employed and these prints have badly faded. Similar tricolor Carbro possesses such as Raylo and Dybro were developed in the 1920’s. Between 1931 and 1939 the Carbro Process was used to create higher quality prints under the Vivex name. Eventually this process would evolve into Cibachrome printing.

Illustration

Tinted Halftone: This is not a process print but a black halftone printed over hand placed color lithographic dots. It was printed by Valentine & Sons under the Carbo Colour trade name but it has only a marginal resemblance to a carbro photo. Postcards were often associated with trade names that might increase sales even when there was no real association to the technique implied.


The Carbro method of producing color photographs was also adapted to the photolithographic process. Instead of layering all three tissue layers together to create a photograph, each tissue could be transferred to a separate litho-stone, which in turn would produce a single printed color image. The color range produced however was limited making many of these images look forced. There were also usually problems with proper color registration. This method was used between the two World Wars and was quickly replaced as soon as a more accurate color printing process was made available.

Postcard

Tinted Gravure: This process printed postcard produced by Fischgrund under the Arco-Iris trade name has the washed out grainy look of an early color photograph, but it is difficult to distinguish the attributes of the transparency from those placed in by a retoucher.


The vast number of printers involved in the early postcard trade make it difficult to know the exact photographic process they based their color images on even when they are printed with process colors. While the exactness that photography provides is usually discernible from the artist’s hand, there was a plethora of experimental photo techniques that a printer might chose to make plates from. Large printing firms might find it in their interest to stick with readily available brand names, but there was also an abundance of small postcard publishers before the First World War that might choose any sort of photo to work from. While the retoucher continued to play an important role in the placement of colors, it should be noted that once even primitive color photography entered the scene, many postcards began to sport a more realistic look./font>

Postcard

Process Print: While this image inspires close associations with early color film, it is difficult to tell how much of its coloration was based on a photograph or the hand of the retoucher. In the detail below we can see that the yellow plate is off register preventing a true rosette pattern to form, but this hue prints so lightly that no moiré pattern is formed.

Postcard Detail

Colorol
Between 1929 and 1930 Agfa-Ansco produced Colorol, a color film consisting of three photo emulsions each sensitized to a different RGB color then sandwiched together (tripack). Each layer was developed and bleached separately before being cemented together. Blue was used for the top layer but the transparent substrate it rested on created space between it and the red and green emulsions that sat face to face. This space caused light scattering that softened the details in the final image. Similar glass plates called Hiblock had been first proposed by Ducos du Hauron in 1895 and prepared in the same manner by the firm Hess-Ives beginning in 1916. This tripack could be used in any glass plate camera but the thicker layers of glass caused more detail loss and poor coloration. The problem was only partially solved when William Tarbin reversed the plate order and began marketing it through Color Snapshots Ltd. in 1928. It was this English firm who licensed the product out to Agfa-Ansco in the United States. A similar film came out in Germany in 1932 produced by Amira, AG. While all these successive versions improved on color, the inability of all the color layers to come into contact with one another continued to cause problems with light dispersal.

Katachromie
The Austrian Karl Schinzel attempted to solve the light dispersal problems inherent in Hiblock Plates with his Katachromie Process. His yellow, cyan, and magenta dyes were all adhered to a single tripack plate, which after exposure was tranferred to a black & white silver based negative. The dye was then bleached out in proportion to its proximity with the silver beneath it revealing a color transparency. This at least was the theory behind the method but it worked poorly in practice. The German Rudolph Fischer improved upon this integral tripack by substituting color forming materials (couplers) for the dyes. During development these couplers would be chemically transformed into color dyes in proportion to the amount of silver formed. While Fischer received a patent for this process in 1912 there was no practical way to produce such a film.

Kodachrome
In 1922 two musicians, Leopold Mannes and Leo GodowskyJr., up with the Eastman Kodak Company in Rochester, New York to further investigate the possibilities of the tripack process. The Kodak laboratories were able to create experimental photo plates for them and within two years they had patented a two color film process. The complexity of this process made it rather impracticable to use, and the dyes on each layer constantly contaminated the other through molecular migration.

A couple years after Kodak discovered less mobile dyes to work with, both Mannes and Godowsky were formally asked to join their laboratory staff in order to exploit this new development. In 1935 they invented Kodachrome by using old principals in a new way. Three layers of emulsion each sensitive to one of the three additive primaries, red, green, and blue would continue to be used, but the problem of light scattering was solved when they found a way to coat them all onto a single substrate. Each layer would only produce a black & white silver based image but the magic of adding color took place in the development process. Since exposure was made directly onto the molecules of the emulsion rather than through a mosaic of artificial filters, more subtitles and detail could be captured with the same three colors. The dyes on this integral tripack however were not very stable and the processing was so complicated that the film could only be develop in Kodak labs. Despite these problems Kodachrome was introduced in 1935, first as motion picture film and then released as slide film the following September.

Photograph

Kodacolor: Kodak introduced color print film in 1942 but its slowness and high cost kept it out of the hands of many amateur photographers. This also prevented it from being used to create real color photo postcards as an identical look could be had with the much cheaper process printed photochrome card.


By 1938 a professional grade of Kodachrome was released after some major improvements had been made in its dyes and the processing method. This new film is first developed into a black & white negative and then each colored layer is re-exposed to filtered light and developed again one layer at a time. The separate chemical baths cause the cyan, magenta, and yellow dyes within it to couple with the appropriate silver emulsion. After the remaining silver and filtering layers are bleached out, a full natural color transparency is revealed. The first postcards to use this film for their color separations were published within a year, though the demands of a looming then actual war would curtail its commercial progress. Even this improved film took highly trained technicians to process, and their limited numbers were now engaged by the military to create enhanced recognizance photos. Use returned in the postwar years, but until the 1970’s Kodachrome remained expensive and its speed slow when compared to black & white film. Its ISO was only 6 when first introduced. These drawbacks limited its marketability with the general public, but it continued to be used by professionals and demand grew for Kodachrome based postcards that were much more convenient to buy.

Postcard

Photochrome: Although this postcard was based a a Kodachrome photo by Mike Roberts, an early pioneer of chrome cards, it is not printed with process colors but a tricolor palette of red, yellow, and blue. While the introduction of Kodachrome ushered in new possibilities, the transition from older techniques was a slow process. There are many such cards as this that cannot be clearly defined.


Agfacolor Neu
IIn 1936 German Agfa came out with Agfa Neu, a color transparency film to rival Kodachrome. It was based on the same principal of coating a single substrate with three different color sensitive emulsions, but here their color couplers were placed directly into the emulsion instead of in the developer. This allowed the film to be developed in only one bath instead of three, which also meant that it could be processed by a small lab or even by amateurs at home. There were however problems with color migration that were not solved until 1941 when the Second World War was already in progress. This product would only become available to the general public after 1949, though it was used to produce propaganda cards during the war. Agfa’s trade secrets however were already passed to the occupying Allied countries in 1945; and when turned over to Eastman Kodak, they were able to introduce their own version of this transparency film as Ektachrome in 1946. The Russians would also bring this technology back to the Soviet Union. While they retained the Agfa name in Eastern Europe, the film manufactured in East Germany that began being marketed to the West in 1964 was called OVWOchrome.

Postcard

Kodacolor: Even though Kodachrome film it associated with the birth of modern photochrome postcards, this is a misnomer. Kodachrome was instrumental to the production of these cards in the United States, but other films were used, most notably Agfacolor Neu on early German chromes. The natural color on this German card was rendered through a tricolor palette of red, yellow, and blue.


Postcard

Tricolor and Process Print: After World War Two the production of photochromes (chromes) were based on both Kodak and Agfa films in Western Europe, but the Eastern Block countries and the Soviets relied almost exclusively on the Agfa process. This gives their photo based cards a slightly different look than most American cards of the same period. Although the Russian card above from 1960 was probably based on Agfacolor, its tonalities and color leave something to be desired because it was still printed in red, yellow, and blue line block as in decades earlier. There is much improvement on the Russian card below from 1967 printed in offset lithography. While process colors are used, the greens and violets are enhanced because of the film used.

Postcard

Since the later 1940’s there have been a whole range of new films that have entered the market for the short and long term, each with their own particular color balance. While both color and speed have steadily improved they are all based on either the Kodachrome or Agfa Neu layering models. These films form the foundation of most imagery printed on postcards through offset lithography. With advancements in digital photography the use of film has drastically declined, and fewer postcards now use it as their starting point. The production of Kodachrome ended in 2009, and since then various forms of Ektachrome have also begun to be discontinued. While film still exists, its use in commercial printing has almost completely disappeared.






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