|Guides Home History Glossary Publishers Artists Topicals Collecting Blog Calendar Contact|
Photography and the Black Arts - part three
Usage of the term gravure is often commonly 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 made 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 rotogravure.
W.H. Fox Talbot continued the experiments that Thomas Wedgewood began in 1802 in which he captured an image on photosensitized paper; but it was in 1835 that Talbot finally found a way to permanently fix this transferred image so it would not fade away under light. While this marked the beginning of true photography, Talbot also sought out ways to incorporate the photographic process into 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 photosensitizing it with gelatin. The copal acted as an acid resist but one 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 use as a printing substrate, but the plate’s surface remained very delicate and this method only saw 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 aquatints for copal. Once the rosin was melted onto a plate’s surface to create a random dot pattern, a clear photosensitive dichromate gelatin emulsion is applied. When dry, the plate is then exposed to light through a positive transparency. Areas where light hits the gelatin are hardened to form an additional acid resist, and the remaining water soluble gelatin is then washed away. This will leave some areas of the plate’s surface around the baked on rosin crystals completely exposed, while others areas will retain a thin gelatin coating in proportion to its exposure to light, which is determined by the density of the transparency that covered it. 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 be eaten away in proportion to its thickness, slowly revealing more bare metal to the acid. Areas that have less contact time with the acid will not etch as deeply as those that do, and these shallow wells will hold less ink producing lighter tones when printed. Since the plate is slowly etched down, the final print can hold very subtle gradations.
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 some printers sought ways to reduce cost. The Jaffe Brothers in Vienna expanded upon Talbot’s photographic veil in 1877 by 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 placed within the photosensitive gelatin emulsion. All the alternatives faired worse in the marketplace, so despite the cost photogravures remained in production up into the 1930’s, but only to produce higher end postcards. Most printers however eventually switched to the more expedient process of rotogravure, and only a handful of fine printers use this photogravure today.
Photogravure: The tonalities produced through photogravure on this early postcard appear almost continuous and unbroken. Even under high magnification the texture is so tight that it makes the process difficult to identify. The occasional small white dots characteristic of the underlying aquatint are the only giveaway visible 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 look wormy as their shape is determined by the curdling of light hardened reticulated gelatin emulsion. A further distinction between these two processes is in their tonal structure. On close examination the ink on a photogravure sits as a crust atop a paper’s surface creating rich flat blacks while the thiner ink 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 substantial problem, these descriptions 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 creating chain like patterns that are wormy like 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 light subject matter in photogravure may be etched so lightly that only a trace of ink is printed.
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 causing the image rendered to lose coherence. This effect is further exaggerated by the uncoated paper it is printed on, which softens the edges of objects by absorbing ink.
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 from a separate plate to carry the lighter values and give the entire image a pleasing warm cast.
Crayon Gravure: This roadside postcard from the 1960’s reproduces a drawing made 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 overwhelms any printed texture making the technique difficult to discern. The darkest areas found in the lettering are revealing; they have very coarse edges and a body filled with small 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 adapt the process to fast rotary presses because it was impossible to expose a large metal cylinder 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 allow gravure to migrate to the rotary press because it could easily be exposed anywhere and later wrapped around a copper coated cylinder. Once adhered, 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 trade 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. This process, so adept are reproducing photographs was also capable of reproducing artwork with the same fine qualities 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 to act as 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 transparency. 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 it is rolled through 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 that tend to only capture ink around their edges will print lighter. The screen pattern completely disappears in the non-image areas of the cylinder that do not receive an etch. 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 dense blacks where the ink is pulled out of the wells to produce a heavy plate tone.
Rotogravure: These two details reveal the grid like cell patterns found in rotogravure. While the regular pattern above was created with a typical crosshatched line screen, the more irregular pattern below demonstrates that there was more than one type of screen type for printers to choose from. While patterns other than crosshatching are less visible, they were more difficult to make and saw less use.
During printing, the etched screen cylinder revolves through an ink fountain where it is coated with fluid ink. Eduard Mertens invented a wiping blade (doctor blade) that clears ink away from surface areas of the cylinder while leaving ink safely in the depressions protected by the crossline grid. When paper passes between the etched 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. The expense involved in making cylinders often caused them to be reserved for very long runs on web-fed presses. 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 picked up soon after by commercial printers. While these new changes to the gravure process made it much more commercially viable, it was not typically used by American printers for postcard production. It did however gain great popularity in Europe where many monochromatic cards were produced by this method. While designed for use on rotary presses, rotogravure postcards were usually made on sheet-fed presses.
Rotogravure: Since 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 actually only hugging two edges within each square inkwell, and as it spills out over a large surface area, it forms a screen-like pattern.
Rotogravure: This postcard from 1915 captures so much detail that it can be mistaken for a collotype even 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.
Toward the end of the 20th century, the use of gelatin tissue in the rotogravure process began being replaced with a high contrast photopolymer emulsion that was usually sprayed directly onto the copper plated cylinder. This not only allowed printed images to be made with higher resolution, it dramatically speed up production time. Its widespread use however has been curtailed by the introduction of electromechanical engraving based on digital technology.
Monochrome Rotoravure While the blue tones of this postcard image have some associations with a wintery landscape, there were no set rules that printers followed when matching color to subject matter on monochromes. It is not unusual to find the same image printed in different hues.
The audience for monochrome postcards was much larger in Europe than in the United States. This was at least in part due to preferential differences among customers. Most of the monotones popular in Europe were printed in a fine high quality gravure, which made them more expensive. Price was a more decisive factor in the United States, and cheeper lithographic postcards of varying quality were produced instead to meet consumer demand. Being the easiest to print, postcards of only one color have been used since their inception, though in postcard’s golden age, monochromes were just another minor variation to what was then available. Many of the monochromes that became common by the 1930’s were printed by less expensive means than gravure 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 palette instead of the usual CMYK process colors used in offset lithography. A separate cylinder is made for every color that is needed to print. In the detail below the typical square cells of rotogravure are still evident despite all 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 illustrations. This postcard from 1952 shows that publishers recognized the unique benefits of this look, and they continued to employ the process even when cheeper alternative printing methods were available. In the detail below it is obvious that the direction of the gravure cells have been rotated to closely imitate the rotation of dot screens used in process printing. The similar rosette created helps to hide the cells and eliminate unsightly interference patterns.
Color Rotogravure: Even though the details below of this postcard pictured above 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 visual hints.
Photo Rotogravure: The flatness of the colors on the postcard above would suggest it was made through lithography while it actually consists of rotogravure dots printed in a light red, yellow, and blue. Even though the dark blue printed as a solid gravure tone works as a key, it also displays a modern tendency to render images more abstractly through color fields rather than line. Here style trumps technique.
Color Rotogravure: The darks in this early color rotogravure 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 make the card look as if it was printed with an RGB palette even when RYB colors 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 its large inkwells, which also help give the image a softer look.
During the 19th century, lithography&rsquo: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 innovation 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 still in use, and produces most of the world’s postcards today.
While the photocrom process was a unique type of photo based printing technique, it was in many ways little more than the natural evolution of chromolithography in the face of advancing technology. The process would largely ignore optical blending and continue to use many separate printing substrates to create of each tone of the same color. Just when the chromolithographic palette seemed to be narrowing, the photocrom process reversed this trend and expanded the use of color. 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 colorful look of chromolithographs that they were comfortable with. Although 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 used this process were so few that variances can be examined through the products of each firm.
Photo-Chromolithograph: This postcard may have only been printed in three RGB colors but nine different sones were required to present three relative values of each hue. These subtle differenced in tonality are 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 that 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 to provide more definition or completely drawn in by hand.
Photochromie: Even though areas of color on this postcard by Nenke & Ostermaier are too localized if not also too intense to look natural, the image still manages to hold a very strong photo like appearance. This is usually a clear sign that a card is based on a black & white photograph that required the additional hand of a retoucher to add color.
Photochrom Process (Aäc Process)
NOTE: Photo-chromolithographic photochroms should not be confused with photochromes used to reproduce natural color through tricolor printing.
Photochrom: Unlike the color fields in traditional chromolithography where many multiple color dots were employed to create a 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 within the same image created a distinct mannered look that was typical of photochroms. This unusual contrast is evident in the two details below.
The Photochrom process begins with multiple litho-stones that are coated with a photosensitive Syrian asphaltum (bitumen) dissolved in benzene. When dry, all the stones are then all exposed to the same photo negative through contact printing. No line screens were used in any part of this process. The bitumen 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 any texture that is needed. 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 removed or drawn in. Each stone then went through a very complicated etching process, which is where most of the technique’s trade secrets lay. This manipulation of processing variables determined the nature of how and where the ink grain printed, which 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 could capture a fair amount of detail with a great clarity of color even though completely broken down into small granules; but since they were based on black & white photographs, the handling of color by retouchers could render the same image either 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 palette on the card below has produced a dull image more typical of a tinted halftone than one produced through photo-chromolithography.
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 thin 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 could then be drawn upon and processed in a manner fairly typical of traditional lithography.
Photochrom: Like many firms, Orell Fussli & Co. established an office in London to help with the distribution of their products. Three tears later in 1896, the Photochrom Company took over Fussli’s London office and began publishing similar postcards after securing the exclusive English license for the Swiss Aäc process. This technique referred to as photochroms was used to produce a great number of view-cards of Europe. While they captured the same fine details as similar Swiss prints, their pallet was much softer and often reduced.
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 photo-chromolithographic 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. This effect was enhanced by using an earthly palette suitable for rendering landscape as seen in the detail below.
Phostints: The Phostint process was always being tinkered with resulting in cards with different qualities. Although the early Phostint pictured above was printed from many different stones, a more simple RGB pallet still dominates its color scheme. The card below, printed at least six years later uses much brighter hues and is generally sharper in appearance.
There have always been differences in color when any company reprinted their cards because the printing plates were remade from scratch. There was usually 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. When color is nothing more than a choice, the same choice may not be made twice rendering differences in a card’s printing. Phostints became particularly known for their wild color shifts that could render two or more very different images from the same photograph. While controlled by the technical aspect of the process, the look itself has more to do with decisions made by those handling the processing. By redesigning through alterations in processing, a single photograph could yield many different images. While it was impossible to reprint a card with the same look, The Detroit Publishing Company may have exploited this situation to purposely create variations that would find a wider audience.
Phostints: Both the postcard above and the one below were made through the same Phostint process and based on the same photographic negative, yet two very different results were produced. Part of the difference is derived from a change in palette, but more importantly from the way in which each of the stones used were etched.
Phostint Details: These two details from each of the two cards further up. In the detail above we can see the use of brighter reds but contrast is also darker due to a more dense accumulation of black. In the detail below there is a much heavier use of black throughout the image in the form of a fine grain, which lowers its overall color saturation and helps to unify the image.
Phostint: Since 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 neutral look, these tones comprise of at least three different hues.
Phostints were often referred to as the Cadillac of postcards because of the fine tonalities, details, and rich color this process was capable of creating. This reference cannot just be considered hyperbole for in an age with little color photography they were able to create images that combined the beauty of an artist’s palette 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 they fed their furnaces with all written documentation along with leftover cards and working proofs to provide heat for their factory, and the secret techniques they so carefully developed over the years died with them.
Phostint: Photo-chromolithographs often give the impression that they capture fine details well, but as we can see from this long detail of a Phostint above, 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 give a hint of their photographic origin, but they are laid down with such fidelity that a very strong overall photographic resonance remains. This is why these marks can provide definition even without a key plate.
Photochrome Process: Memory proved faulty in the absence of documented procedure, and the new Photochrome did not match the vitality of the old Phostint. The dissimilar appearance seems to be mostly due to the different way that the ink sits on the paper.
Poly-Chrome: In this postcard from 1906 large areas of flat tones are used in a manner similar to the Swiss Aäc process but with little of its fine grain. There is much evidence of heavy retouching by hand in the darks as seen in the detail below. This helps to enhance the sharpness of the image.
Poly-Chrome: When a picture on a Poly-Chrome is broken down into just a few flat fields, its photographic base helps it retain much of its realistic appearance. Sometimes 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 to provide the illusion of fine details that are not there. Even when true details are lacking, the mind’s ability to extrapolate is enhanced when visual information is picked up from the subtleties provided by a photo-based image.
Most Poly-Chrome postcards seem to have been published by the American News Company between 1903 and 1907, but the same trade name and logo can be found on much later cards published by other firms. These late cards however were usually 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 in appearance to Poly-chromes. While it uses screenless lithography to reproduce its photo-based composition in black and grey, there are also obvious signs of extensive 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 makes it one. All cards in this series are characterized by a limited pallet with a dominant orange hue, which gives them a hand drawn look.
Photo-Chromolithograph: A good number of photo-chromolithograph postcards were made where there is no reference to publisher or printer as on this Russian postcard. The process however can still be identified as being a photo-chromolithograph by closely examining the clumpy details of the printed grain seen below.
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 above and below we can sense they are more the result of a photomechanical process, but careful observation must be made to filter out this texture from dots drawn in by the hand of retouchers.