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Photography and the Black Arts - part three
In general usage the term gravure is often applied to any photo-intaglio technique but it specifically makes reference to prints of fine grain made through the photogravure or rotogravure process. Gravure is an old technique and it could be argued that the very first photographs in the form of heliographs were actually gravures. The gravure process has continued to evolve since its inception and is still widely used in commercial printing today. It was used in the production of many postcards but it was a pricey technique that limited its application. Most higher end monochrome postcards printed in Europe between the two world wars were produced through gravure.
W.H. Fox Talbot continued the Experiments that Thomas Wedgewood made in 1802 in which he captured an image on photosensitized paper; but 1935 it was Talbot who finally found a way to permanently fix this transferred image so it would not fade away. While this marked the beginning of true photography, Talbot also sought out ways to utilize photography in printing. By 1852 he began experimenting with gelatin emulsions (fish glue) for their potential use as an acid resist in etching photographic images onto metal plates. Six years later he realized he could achieve richer tones by first coating the polished metal substrate with a dusting of gum copal powder, which was melted onto the plate before sensitizing it with gelatin. The copal also acted as an acid resist but with a delicate irregular grain. It also guarantied that a fine texture would be bitten into the plate even if too much of the emulsion was washed off.
PHOTOGRAVURE (Hand Gravure)
Printers had seen potential in daguerreotypes and by the 1840’s some were being etched and engraved upon to strengthen the image for printing, gut the plate’s surface remained delicate and this method had limited use. Eventually the photoglyphic engraving process as used by Talbot evolved into photogravure (called heliogravure in Europe) by substituting the same fine resin powder as used in aquatint for the copal. Once the rosin has melted to a plate’s surface to create a random dot pattern, a clear photosensitive dichromate gelatin emulsion is applied. When dry it is then exposed to a positive transparency where the gelatin light hardened areas form an additional acid resist. The remaining gelatin is wash away in proportion to the density of the transparency that covered it, either nearly or completely exposing the metal surface of the plate. The plate is then heated at a higher temperature making its surface very hard, and the remaining resist is sometimes dyed a dark hue to better observe the image against the exposed metal. When placed in successive acid baths of decreasing strength, the metal will first dissolve in the exposed areas between the rosin dots. The thinner areas of gelatin will eventually wear away in proportion to their exposure to light and reveal more bare metal of the plate underneath. Because these areas have less contact time with the acid they will not etch as deeply, and these shallow wells will hold less ink producing lighter tones when printed.
Photogravure produces thousands of irregular ink cells in varying depths that can merge into a subtle continuous toned image with very rich blacks. In addition the printing plate is also very durable, able to yield sixty thousand impressions. Though the results obtained by this process are of a higher quality than many other printing methods, its complexity makes it relatively more expensive and others sought ways of reducing cost. The Jaffe Brothers in Vienna expanded upon Talbot’s photographic veil in 1877 using millers gauze to break up the image while being photomechanically transferred. Other techniques such as the stagmatype (spitzertype) introduced in 1866 featured a gum grain with the photosensitive gelatin emulsion. All of the alternatives faired worse in the marketplace, so despite the cost of photogravure this process continued to be used even after the introduction of rotogravure and up into the 1930’s but only to produce higher end postcards. Only a handful of fine printers use this process today.
Photogravure: The tonalities of photogravure on this early postcard appear almost continuous and unbroken even under high magnification and are often difficult to identify. Only occasional small white dots from the underlying aquatint may be visible as seen in the detail below.
The printing plates used with photogravure and collotype both hold ink in the spaces formed between particles of resist that leave their own distinctive patterns on the final print. They show up as white dots on photogravure from where the grains of aquatint once sat on the plate preventing it from biting in the acid bath. The small white marks on collotypes tend to be wormy in appearance as they are the result of the light hardened reticulated gelatin emulsion. A further distinction between these to processes is in their tonal structure. On close examination the ink in photogravure sits as a crust atop a paper’s surface creating rich flat blacks while the thiner ink film of a collotype produces a good range of grey but poor dark tones. While these are the major differences to look for in making a determination of technique there is a problem, they do not always hold true. Many different patterns can be created with aquatint. If the rosin crystals are heated too long or over too high a heat they can melt into each other. This can result in chain like patterns that are wormy similar to curdled gelatin. The various practitioners of collotype had many trade secrets that often rendered the texture of one different from another. Sometimes the white marks produced are so small they have no distinctive shape at all and cannot be differentiated from a fine aquatint. Some of these printers also managed to push the collotype process into producing real blacks while the dark crust of photogravure will not appear on printed material of light subject matter.
Photogravure: Photogravure’s tendency to render soft tones works against it on this postcard. The atmosphere of this distant landscape provides little contrast and few details to pick up on and the image rendered looses coherence. This effect is further exaggerated by the soft uncoated paper it is printed on.
Duogravure: At first glance this postcard in photogravure appears to be printed in a deep brown. The detail below reveals that a lighter brown has been printed under the black to carry the lighter values.
Crayon Gravure: This roadside postcard from the 1960’s reproduces a drawing in pastel or color pencil. It is printed with the same CYMK pallet used in process printing but it looks richer because it is printed in gravure. The loose nature of the drawing leaves much white space on the paper, which in turn makes it difficult to discern any printed texture. The darkest areas as in the lettering are revealing. They have very coarse edges and a body filled with white dots typical of photogravure.
ROTOGRAVURE (Machine Gravure)
Photogravure had been used in commercial printing since the paper fed press was developed in 1863 but there was no way to expose the large metal cylinder of a rotary press to a photograph through a halftone screen. In 1864, J. W. Swan discovered a way of transferring an image onto a metal plate by using a photosensitive gelatin tissue and in 1879, Karl Klic replaced Talbot’s first step of aquatinting a plate by infusing the gelatin tissue itself with a dot pattern. This new tissue was not only able to produce an attractive random grain along with fine detail, Klic’s method provided the most consistent results and it soon became the most widely used. Just as important the use of gelatin tissue would eventually allow gravure to migrate to the rotary press. The tissue could easily be exposed anywhere and later wrapped around a copper coated rotary cylinder. The cylinder could then be etched by rotating it through a tray of acid. Rather than patent and license his invention, Klic hoped his Rembrandt Intaglio Printing Company could keep a monopoly on the process; but when an apprentice left for America he took the secret with him. By 1904 rotogravure was in widespread use and producing countless postcards. While rotogravure was designed for use on a rotary press these plates were sometimes printed on flatbed hand presses.
Rotogravure: The postcard above is typical of rotogravure printing. None of its ink cells are visible to the naked eye; instead we are provided with a wide tonal range, smooth transitions, and deep velvety blacks with a matte finish. The process was capable of reproducing artwork with the same qualities achieved with photographs as seen on the card below.
In 1908 two textile printers, Eduard Mertens and Ernst Rolffs took rotogravure’s development much further. Rolffs developed a method by which a gelatin tissue is double exposed, first to create a solid crossline screen pattern across the entire surface of the cylinder in the form of an acid resist. This screen will not print but remain white while allowing the square cells between them to be further exposed. The second exposure is then made with the transparency that holds the image, which causes the square cells to harden in proportion to the amount of light filtering through the film image. The tissue is then adhered to a cylinder and the soft areas are washed out with water leaving a hard acid resist behind. The acid bath will incise a continuous toned image into its surface between the screened lines by creating small ink cells of substantial but varying depth. The deeper depressions will transfer more ink to the printing surface creating darker areas while the shallow inkwells will print lighter. The areas of the cylinder that are not etched at all become the non-image areas where the screen pattern completely disappears. In dark areas the fine lines of the screen pattern that were not etched will leave behind a faint white grid around the wells. These lines are too small to be visible to the naked eye especially in areas of black where plate tone tends to spread across the surface to obscure them.
Rotogravure: These two details reveal the grid like cell patterns found in rotogravure. While the regular pattern above was created with a typical line screen the more unusual pattern below demonstrates that there were a variety of screen types for printers to choose from.
During printing the etched screen cylinder revolves in an ink fountain where it is coated with fluid ink. Eduard Mertens invented a wiping blade (doctor blade) that clears ink away from the surface areas while leaving ink safely in the depressions of the cylinder protected by the crossline grid. When paper passes between the etched crossline screen cylinder and an impression cylinder, its soft rubber covering pushes the paper into the steep incised ink cells and the image is transferred onto the paper. This mechanical inking process sped up printing time considerably and it replaced the old hand inking and wiping methods within two years. Because cylinders were expensive to make they were most often reserved for web-fed presses used for very long runs. For pressruns of a million or more, the cylinders are plated with chromium to provide extra durability. This process was patented in 1910 and was soon being used in commercial printing. While these new changes to the gravure process made it much more commercially viable it was not typically used for American made postcards. In Europe however many monochromatic cards were produced by this method but usually on sheet-fed presses.
Rotogravure: Because the ink used in rotogravure is transferred out from deep wells in the plate’s surface it can lay thickly on a paper’s surface once printed. This often forms a rich even tone, which can make this medium difficult to discern. Evidence of the technique can best be found in the inky crust that builds up in the darkest areas while the inherent grid pattern is easiest to observe in the lighter tones that carry less ink. While the detail below seems to reveal white boxes in a dark grid this is only an illusion; the ink is hugging only two edges within each inkwell, and as it spills out over a large area it forms a screen-like pattern.
Rotogravure: This postcard from 1915 captures so much detail one may think it a collotype though its rich darks are closer to gravure. On close examination the only grain seems to be that of that caused by the papers fibers. It is very easy to mistake this card for a photogravure for it is only in a few of the white details as seen below that the faint pattern of a rotogravure plate shows up.
In the later 1900’s gelatin tissue was replaced with a high contrast photopolymer emulsion that was usually sprayed directly onto the copper plated cylinder. This not only creates printed images with higher resolution, it can dramatically speed up production time. Its widespread use however has been curtailed by the introduction of electromechanical engraving based on digital technology.
Monochrome Rotogravure While the blue tones of this postcard image have some associations with a wintery landscape, no rules were generally followed when matching color to subject matter.
The audience for monochrome postcards was much larger in Europe than in the United States. Part of this was due to preferential differences. Most of the monotones popular in Europe were printed in a fine high quality gravure making them more expensive. Price was a more decisive factor in the United States and cheeper lithographic postcards of varying quality were produced instead. Being the easiest to print, postcards of one color have been used since their inception. In postcard’s golden age monochrome cards were just another minor variation to what was then available, but by the 1930’s they became extremely common in efforts to drive down cost. After the introduction of cheep photochrome postcards, the monochrome postcard disappeared in relevant numbers.
Color Rotogravure: When printing in color rotogravure, red, yellow, blue, and black is the standard pallet instead of the usual CMYK process colors used in offset lithography. A separate cylinder is made for every color used in a print. In the detail below the typical square cells of rotogravure are still evident despite the over printings of color ink.
Color Rotogravure: While a black gravure key plate has no problem translating a photographic image, colors always seemed forced as if applied by hand, making the color gravure process more suitable for reproducing illustration. This postcard from 1952 show that publishers saw benefits in this look even when alternative printing methods had become available.
Color Rotogravure: Even though the details of this postcard lack high clarity, color rotogravure in the right hands could be used to create wonderfully subtle results. High resolution is not always needed because of the minds ability to extrapolate on what it sees.
Photo Rotogravure: The flatness of the colors on this postcard would suggest it was made through lithography while it actually consists of rotogravure dots in a light red, yellow, and blue. Even though the dark blue printed in a solid gravure tone works as a key, it also displays a more modern tendency to render images more abstractly through color fields rather than line. Here style trumps technique.
Color Rotogravure: On this early color rotogravure the darks take on the typical solid crusty characteristics of most work in gravure but the highlights are printed with such fine marks that the technique is almost indecipherable. The small ink wells have created a sharp clean image with fine detail. Note the effort made to render the image in RGB colors even though a RYB pallet was used.
Color Rotogravure: Modern rotogravure is now capable of producing much richer color mixes. While the process as used here has not created the natural color that is often associated with photochromes, it has manage to remain competitive by producing a rich and enhanced color mix reminiscent of a hand colored photo. Technique is no longer affecting appearance as much as a desired look is determining technique. In the detail below the gridlines of the plate are clearly visible due to the large inkwells, which also help give the image a softer look.
During the 19th century lithography’s dependence on a substrate of heavy limestone nearly doom this promising medium to oblivion. Photographic transfer was very difficult and stones could not be used on fast rotary presses while metal litho-plates were found to be too fragile for extended commercial use. Line block printing, which became its chief competitor, may have overtaken it had it not been for the invention of gelatin tissue. This inovation caused revolutionary changes in lithographic reproduction and returned it to the status of a competitive medium. It would be used to create a new generation of multi color postcards just as traditional chromolithography began to fade. Most early photolithographic techniques would be abandoned by the 1920’s but color lithography would continue to evolve into photo-offset lithography, which is used to produce most of the world’s postcards today.
While the photocrom process was a new type of photo based technique, it was in many ways really little more than the natural evolution of chromolithography in the face of advancing technology. Many separate printing substrates would still need to be created for each tone of the same color as there continued to be minimal use of optical blending. Just as the pallet for chromolithographs seemed to be narrowing, the photocrom process reversed this trend and expanded the use of colors. Only now random photographic grain and speckle would replace artist drawn dots and spatter. This technique provided an outlet for the public’s fascination with photography while retaining the look of chromolithographs that they were comfortable with. Despite the fact that many of the postcards created were far from the truthfulness of a photograph and in the colors of nature that their catalogs boasted of, this was a winning combination that attracted a large market. While a number of companies would develop and even patent similar techniques, those who actually used this process were so few that variances can be examined through each firm.
Photo-Chromolithograph: This postcard seems as if it were only printed in three RGB colors when actually nine were used. Three values of the same relative hue were each created with a different plate, which is more noticeable in the enlargement below.
Photochromie (Vidal Process)
Photochromie: The details of the rocks on this postcard by Purger & Co. are so realistic and minute they could have only been based on a photograph despite the coarsely printed grain. The train however is very rigid in appearance indicating it was either heavily retouched or completely drawn in.
Photochromie: Even though the areas of color on this postcard by Nenke & Ostermaier are too localized if not also too intense, it still holds a very strong photo like appearance that hints at its origins.
Photochrom Process (Aäc Process)
Photochrom: Unlike the color fields in traditional chromolithography where many multiple color dots were employed to create a more subtle appearance, the color fields in postcards by Photogob were made up of small markings of very similar hues. While this provided their cards with greater color intensity, it also flattened out the space in many of their compositions. The dichotomy between detailed rendering and flat color as seen in the two details below created a distinct mannered look that was typical of photochroms.
The Photochrom process begins with litho-stones coated with a photosensitive Syrian asphaltum (bitumen) dissolved in benzene, which when dry are then all exposed to the same photo negative through contact printing. No line screens were used in any part of this process. The asphaltum hardens in proportion to its exposure to light, and the unhardened areas are then washed away with solvent. At this point the retoucher removes all parts of the image not relevant to the color assigned to that stone (photo-stone) while adding in needed texture. Wool daubers and fine hairbrushes were often used with touche to finely adjust the tonal balance, which required a very delicate hand. In some cases new compositional elements would be drawn in. Each stone then went through a very complicated etching process where most of the technique’s secrets lay. This manipulation of processing variables determined the nature of how and where the ink grain printed that controlled the postcards final look. The stones were then printed in the same manner as a normal chromolithograph. At least six separate stones were required for this process though the employment of ten to fifteen hues was more typical. The resulting images though completely broken down into small granules could capture a fair amount of detail with a great clarity of color; but since they were based on black & white photographs the handling of color by retouchers could render the same image realistic or highly mannered.
Photo-Chromolithographs: While photo-chromolithographs usually have a strong photo-like continence despite their rough grain, extensive retouching can often defeat this look. Colors have been so altered on this postcard above that they not only appear unreal, they distort the pictorial space. The limited pallet on the card below has produced a dull image more typical of a tinted halftone than one produced through this medium.
In 1888 the Wezel & Nauman Fine Arts Company patented their own photocrom process in Germany a day after Orell Fussli filed their patent in Austria. From about 1890 most of their postcards were printed on artificial lithographic stones, a product of their own invention. Through the use of acid and grinding the unusable remnants of true litho-stones were reduced to a pulp to which asphaltum, resin, and oil were added. This mixture was then sprayed onto a zinc plate in a fine even coating. When it had hardened it was drawn upon and processed in a fairly traditional manner.
Photochrom: The colors and grain on the photochrom postcards published by Wezel & Naumann tend to combine into very soft ethereal blends. It is often only through the use of color contrast that details and a readable composition emerges. In the background a minimum of contrast is used to help the space recede but in the two details below we can see how distinctions begin to disappear when the image is reproduced in black & white.
In 1896 the Photochrom Company took over Fussli’s London office established three years earlier and began publishing similar postcards after securing the exclusive English license for the Swiss photochrom process. This technique was used to produce a great number of view-cards of Europe. While they captured the same fine details as the Swiss prints their pallet was much softer and often reduced.
Photochrom: The different color grains used in the Photocrom Company’s postcards tend to be printed in high contrast to one another within any single area. While this created less harmonious color fields it had the effect of uniting the entire composition.
Phostints: The phostint process was always being tinkered with resulting in cards with different qualities. Though the early Phostint above was printed with a number of plates an RGB pallet dominates its color scheme. The card below, printed at least six years latter uses much brighter hues and is generally sharper in appearance.
There have always been differences in color when any company reprinted their cards, but Phostints became known for their wild color shifts that could render two or more very different images from the same photograph. This however has more to due to decisions made by retouchers rather than any technical aspect of the process. There was great latitude in color choices since these cards were made from black & white photos that were only occasionally accompanied by specific notations regarding the placement of hues. By redesigning through alterations in processing a single photograph could yield a variety of postcards that may appeal to a larger audience.
Phostints: Both of these very different postcards were produced by the same Phostint process and from the same photographic negative. Part of the difference is derived from a change in pallet but more importantly from the way in which each of the stones used were etched.
Phostint Details: In these two details from the cards further up we can see the use of brighter reds on the example above but contrast is also darker due to a more dense accumulation of black. On the detail below there is a heavier use of black as a fine grain throughout the image that lowers its overall color saturation.
Phostint: Because Phostints were photo based it is often easy to forget how extensively retouched they were. In this crowded composition the retoucher left the background nearly flat and colorless to bring our focus to the activity up front. Despite the background’s neutrality these tones are actually made up of at least three different hues.
Because of the fine tonalities, details, and rich color this process created, Phostints were often referred to as the Cadillac of postcards. This reference cannot just be considered hyperbole for in an age without color photography they were able to create images that combined the beauty of an artist’s pallet with precise photographic detail. The particulars of their methods were kept such a close trade secret that when Detroit Publishing went out of business in 1932 there were only a handful who knew how to make a Phostint from start to finish. During their last days their furnaces consumed all written documentation along with leftover cards and working proofs in an effort to provide heat for their factory, and the techniques they so carefully developed over the years died with them.
Phostint: Photo-chromolithographs often give the impression that they capture details well, but as we can see from this long detail of a phostint this is only a half-truth. The image is made up of a conglomeration of small markings that are even more irregular in size and shape than found in traditional spatter techniques. Seen close up they do not hint at their photographic origin but even with the absence of a key plate the very strong overall photographic resonance is able to create definition.
Photochrome Process: Memory proved faulty in the absence of documented procedure, and the Photochrome did not match the vitality of the Phostint. This is mostly due to the different way that the ink sits on the paper.
Poly-Chrome: In this postcard from 1906 we can find flat tones similar to the Swiss photochrom process but little of its fine grain. There is much evidence of heavy retouching in the darks as seen in the detail below.
Poly-Chrome: When a picture on a Poly-Chrome is broken down into less flat fields its photographic base helps create a much more realistic image. This has more to do with the choice of composition than from any changes in the manner in which it was printed. This postcard was heavily retouched with additions of small flat blots placed underneath the fine photo grain.
Most Poly-Chrome postcards seem to have been published by the American News Company between 1903 and 1907, but the same name and logo can be found on much later cards published by other firms. These late cards however were almost always produced in an entirely different technique. A few other publishers produced similar photo based postcards through screenless lithography in combination with traditional drawn techniques. Many such cards were produced in Europe, possibly from the same printing firm without any reference to technique or publisher.
Photo-Chromolithograph: This postcard published by Chisholm Brothers makes no reference to technique but it is very similar to a Poly-chrome. While it uses screenless lithography, mostly in black and grey to create its photo-based composition, there are also obvious signs of retouching as in the addition of many hand drawn yellow dots.
Photo-Chromolithograph: While this postcard published by Hugh C. Leighton lacks the varied coloration found on many photo-chromolithographs, its texture is unmistakably of one. All cards in this series are characterized by a limited pallet with a dominant orange hue, which gives them a more hand drawn look.
Photo-Chromolithograph: There are a good number of photo-chromolithograph postcards about where the publisher is unknown as on this Russian postcard. The process however can still be identified by closely examining the clumpy details of the grain.
Photo-Chromolithograph: While photo-chromolithographs are made up of small dots they tend to be very irregular in shape and size and do not have the same patterning as the hand drawn dots of a chromolithograph even when placed down in a haphazard manner. In both these details we can sense they are more the result of a photomechanical process but careful observation must be made to filter out this texture from the work of retouchers.