Aäc is the proper name for photo-chomolithography as invented Orell Fussli. It is also often referred to as the Swiss photochrom printing process. The term is most often used to differentiate the prints and postcards made by Photoglob, a subsidiary of Orell Fussli, from similar looking photo-chromolithographic work.
Acid migration is the movement of acid contained in one material over to another material that is less acidic. This process can occur through direct contact or vapor transfer. Certain plastics like PCV release acid as they age, and most papers contain acid residue because of its use in turning wood into pulp during production. Although the card stock on which postcards are printed all have acid content, some have much greater amounts than others and show the effects of acid contamination much sooner. Acid can migrate onto postcards when in contact with other unsleeved cards or when stored in boxes and album pages that have acid content. The reaction of paper to acid is to yellow or turn brown, and postcards can become brittle over time. This is a leading cause of crumbling edges and breaking corners.
Additive Color (Additive Primaries)
Red, green, and blue (RGB) are the three additive primaries. Additive color theory is based on effects of projected light on human perception, and not the properties of light itself. Primates only have receptors in their retinas to perceive RGB colors. When additive primaries are equally mixed together they produce all visible wavelengths, which are perceived as white light. When only two additive colors are mixed, a third color is made visible in the form of a secondary additive color; blue plus green makes cyan, red and green make yellow, and blue and red create magenta. All the colors of light can be made to the eye by combining different proportions of these additive primaries. These three colors were the most commonly used in the printing of early postcards and for hand coloring palettes. They were usually used as solid fields with a black & white halftone containing detail printed over it, and they were not meant to optically blend into many colors. Efforts were sometimes made to break these color fields down into small markings or dot patterns where limited optical blending could occur.
An advertising card is a postcard with an advertisement printed on it. The first known card to be sent though the U.S. mail in 1848, as well as the first postal authorized by the U.S. Post Office Department in 1872 was used for advertising. Although advertisements still reach us through postcards, the term Advertising Card is most often applied to those cards printed between 1872 and 1901, when they dominated card production and the term Post Card was not yet in use. Postage rates for advertising cards were then one cent, which was half the amount required to send a personal message. They were first printed in black & white and more colors were added until chromolithography was a standards means of production. They are also the types of cards on which a wood engraved illustration is most likely to be found. In the 19th century, trade cards were also sometimes referred to as advertising cards.
The Aesthetic Movement was a loosely defined art and literary movement that existed in Britain from 1868 to 1901. Its origins lie in the Romantic Movement and it became a reactionary force against Victorian morality in the Arts and the blight of Industry on the landscape. The movement held that the Arts should be a source of refined sensuous pleasure, rather than a messenger of morals or the sentimental. They believed art does not need to have purpose; it only needs to be beautiful. The French Decadent writer Victor Cousin coined their favorite phrase, L’art pour l’art (Art for Art’s sake). The Aesthetes developed a cult of beauty in which life was meant to copy art. Though similar in philosophy to other Decadent and Symbolist movements, the Aesthetics in particular imparted much influence on decorative design within the Arts & Craft Movement.
Agfa Ansco is the brand name of a photo paper introduced in 1928 by the Agfa Ansco Company that was created by the merger of Ansco Photoproducts Inc. and Agfa Products of IG Farben in Germany. They became a subsidiary of GAF in 1939, and were seized by the U.S. Government in 1941 as enemy property. World War Two essentially shut down all commercial production of this paper though it continued to be used for military purposes in the United States. This paper was produced in postcard size with a pre-printed postcard back and stamp box holding the Agfa Ansco logo.
Airbrush is the technique of applying atomized particles of ink to a surface with the aid of a small and precise air sprayer. These small particles, which are ejected under high pressure will adhere to the paper in specs of varied size and whose density can be varied by controlling the amount of ink flowing through the nozzle. Abner Peeler patented the first airbrush in 1879, but Charles Burdick’s patent of 1893 refined the design into a model that is more recognizable today. Ink applied in this manner has soft edges that can create subtle blends, but the technique is unable to produce fine detail. Airbrush was primarily used for retouching photographs and illustrative work, sometimes with the aid of stencils. Eventually its commercial use drew the attention of the Bauhaus artists who made much use of it in their work. It was also often used to add color to non-printed embossed postcards in high relief. A highly raised surface would crack any ink pre-printed on it, and it became too irregular after embossing to print on. In addition traditional colorants like watercolor that need more moisture will softened a raised surface and damage it, while the fine mist of airbrush will have little effect on it.
À la Poupée
à la Poupée (with a doll) is method of inking a single intaglio printing plate in multiple colors by applying different inks to it usually with the aid of small hand held cotton daubs (dollies), though different tools can be used. While adding color to just one plate eliminates registration problems, sharp and precise color delineation cannot be achieved and the coloration of individual prints created through this method will vary in appearance. Not only is the application of colored inks by hand indecisive, the hand wiping of a plate’s surface pulls colored ink out from the lines causing them to mix unpredictably wherever different hues meet. Between these variables and the time consuming nature of this method, it was not viable for commercial printing. Though mostly employed by artists since the late 1600’s, this type of inking can be found on etched postcards that were already being printed in very limited numbers.
After Josef Albert refined Louis Poitevin’s Phototypie process to make the first workable collotype, he patented it in Bavaria in 1868 under the name Albertotype. The technique begins with a greyed glass plate coated with a photosensitive dichromate colloid gelatin that puckers and cracks as it dries. When exposed to light through a reverse negative, the lit areas harden into an insoluble nonabsorbent finish. It is the areas within the reticulated cracks that harden the most because they are the thinnest part of the emulsion. They in turn will print the darkest in proportion to the tones of the original image. The dichromate emulsion in areas with little or no exposure to light remains soluble and is washed out from the gelatin with cold water. The plate is then printed in a similar manner to a lithograph. A solution of glycerin and water is spread over the plate’s surface, which is absorbed by the remaining gelatin. Areas that are to carry the dark tones absorb little or no moisture while areas for the lighter tones and non-image areas absorb the most. When greasy ink is rolled over the gelatin on the plate, the non-image areas holding the most moisture repel the ink, and the dry hardened image areas attract the ink. Once printed the reticulated pattern creates a continuous toned image of incredible detail for which it is prized. Eventually a ground glass plate was substituted for the original copper substrate creating better adhesion of the emulsion, which in turn allowed the process to be commercially used. When Albert patented this process in the United States one year later it was given the name Artotype. The term Albertype is sometimes used interchangeably with all forms of collotype. The process was widely employed to produce book illustrations and postcards, especially in Europe.
Albumen is an animal protein most often obtained from the whites of eggs. It contains long chained amino acids whose bonds create large molecules of protein (polypeptides). When heated each molecule comes apart and forms new bonds with the other unraveling proteins creating a gelatin. Albumen was often combined with dichromate or silver nitrates to produce photosensitive emulsions. These emulsions have a very short shelf life and were usually prepared just before use. Louis Desiré Blanquart Evrard was the first to use albumen to create photo paper in 1850, but the yellowing caused by its high sulfur content caused it to be replaced by better alternatives starting in the 1890’s. About 85 percent of all photographs from the 19th century are on albumen paper. Better papers that followed were often toned the color of albumen to meet the public’s expectation of what a photograph should look like.
Album marks refer to the damage imparted to postcards by the albums they were once stored in. The most common form of this damage is a diagonal embossing across a card’s corners caused by the pressure of the cut paper flap that once secured them to an album page. This type of embossing may be accompanied by black marks along their edges, which are transferred from the dye in album pages. Acid may also be transferred to the front of the card by this overlapping paper, leaving behind triangular yellowed corners. As many postcards were glued into albums pieces of the pages may remain stuck to a cards card’s back when removed. Acid migration from any remaining glue or paper will further damage the card.
Alien Contract Laws
Immigration to the United States increased dramatically in the 1880’s during a period of economic decline. This added stress inevitably brought about calls for Congressional legislation to address the situation. The Chinese Exclusion Act of 1882 and the Alien Contract Labor laws of 1885 and 1887 prohibited certain laborers from immigrating to the United States to work under contract. In 1891 the Federal Government assumed the task of enforcing these laws and created the Immigration Service. Operations began in New York Harbor at Ellis Island, which opened on January 2, 1892. Since most immigration laws were designed to protect American workers, immigration responsibilities were transferred from the Treasury Department to the Department of Commerce and Labor in 1903. Alien Contract law prevented the highly skilled artists and craftsmen of the German printing houses from working in the United States. As demand for postcards grew, many American publishers were forced to send their own artists to Germany to keep up production.
Alphabet Card (Letter Card)
An alphabet card is a postcard that features a single letter, often ornate and accompanied by an illustration or decorative graphics. These cards were published in both full alphabet sets and individually. Many images of actresses were issued as real photo alphabet cards. The origins of this style come from more than one tradition. The most obvious is that of illuminated letters and alphabet books published to aid in the instruction of reading, but there are also more esoteric roots as letters can be endowed with magical meaning.
Alumino (Aluminum Cards)
Alumino is a trade name that was used for novelty cards printed on aluminum in Great Britain.
The term Americhrome was originally used as a trade name for tinted halftone postcards distributed by the American News Company. They consisted of a limited color palette of lithographic dots that was overprinted with a medium halftone key in black. Most early Americhromes can also be characterized by their turquoise skies and small red block lettering. In later years there were very different types of cards with white borders and fine textured linens that continued to carry the Americhrome name. Their only commonality is that they were all printed in the United States.
Anaglyphs, patented by Ducos du Hauron in 1891 are two-dimensional images that create the illusion of three dimensions. As in stereoscopy they are produced with two photographs taken of the same scene at slightly different angles, but here one is taken through a red filter and the other through a blue, green, or cyan filter. One image is then printed over the other each in the same solid color as the filter it was shot through. The final image appears to be seriously off register until viewed through a special pair of glasses that creates a 3D effect. Each lens of the glasses is a different color filter that corresponds to the printed ink. The red filter makes the red ink of the image appear white and the blue ink as black while the blue filter in the other lens has a complementary affect on the blue ink. The brain interprets the differing color contrast seen by each eye as space. While its use on postcards has been minimal, this process has since been integrated into other mediums such as movies and comic books but its popularity has been sporadic.
Aniline inks are a type of inexpensive printing inks consisting of synthetic organic pigments produced as derivatives of nitrobenzene, dissolved in a methylated spirit, and bound with a resin. This ink is available in all colors but it has poor light fastness and is considered fugitive. Despite this drawback the ink’s fast drying time made it compatible with high speed presses, which drew the interest of printers that produced linen postcards. By the 1940’s many health hazards were associated with these toxic dyes and the industry switched back to pigment based inks until better substitutes were found in 1949. If dampened, Aniline ink will often run leaving a pink stain behind (Pinking).
A card published to advertise an event rather that a product is often referred to as an announcement card. They are given out free for publicity but can sometimes demand a price as a souvenir once their usefulness has ended. The most common form of this card is also known as a gallery card, used to announce and publicize art exhibitions. Many of these cards are not made in standard sizes so they will be better noticed.
April Fish (poisson d’avril)
April Fish is the name applied to the victim of a practical joke on April Fools Day (All Fools Day) in France. Many postcards were produced to celebrate this day, and those from France always contain an image of a fish within the composition. There have been many attempts to explain this custom with reasoning linked to the change in the Gregorian calendar to the signs of the Zodiac but they are all problematic. The connection of fish to April Fools Day dates back at least as far as the Middle-Ages but little else is known for certain. The character of the fool is an archetype found in many cultures since ancient times.
An Aquarellchrom is a trade name used by the Aristophot Company for their continuous toned lithographic postcards that resemble watercolors or pastels. This technique was usually reserved for artist signed cards that were printed in Leipzig.
The intaglio process called aquatint was in use since the 17th century to get around the limitations of having to manipulate line to create a tonal range. In this process a metal substrate is dusted with a fine powder of rosin or asphaltum that is then adhered to its surface by applying heat from underneath. The tiny melted particles act as a chemical resist so that when the plate is exposed to an acid bath, an irregular pattern capable of printing tones will be etched into it. These patterns can be somewhat controlled by varying the amount of dust applied, the size of the crystals in the powder, the amount of heat the plate is exposed to, and of course by the length of time the plate is etched in acid. By painting on an additional acid resist (stop out) to selected areas of the image during the etching process, some parts can be covered to print white or a full range of tonal values in subsequent acid baths. Plates holding etched aquatint patterns can also be burnished to shallow out their ink cells, which in turn will bring it up to white or just lighten its tone. The surface of aquatints are very shallow rendering them very susceptible to wear, so they do not hold up well to the large press runs required by commercial printing. Its use for the most part was replaced by lithography in the early 1800’s and rarely employed afterwards outside of the fine arts except in very limited printings. While not used to produce postcards in its pure form, the aquatint process was eventually combined with photogravure to give it a finer more even texture.
Arcade cards, made on heavy stock were designed to be distributed through penny vending machines usually found at amusement arcades. They tend to depict popular images of sports figures, movie stars, suggestive cartoons, and pin-up girls, though a wide variety of subjects were covered. These cards were often poorly printed, usually in black & white or bright monochrome tints, though there are notable exceptions in full color. Though most arcade cards were just produced for collecting, they were sometimes mailed because of their similar size to postcards. While most of their backs were blank, some arcade cards were made with a dividing line and stamp box printed onto them but these are not common. Around since the turn of the century, interest in arcade cards peaked in the 1930’s and then faded away during the 1960’s.
Archival is a term usually applied to an object that insinuates its long-term stability, or the quality of not affecting an object’s stability. It is used in conjunction with materials used to store postcards inferring that they have no acid content that might damage paper. There is no internationally accepted definition.
Arisierte (Aryanized) Business
An Arisierte business is one owned by someone considered to be an Aryan, which was transferred from Jewish ownership through coercive measures. When the Nazis came to power in Germany they called for a boycott in 1933 of all goods produced or sold by Jewish merchants. The boycott had little practical effect but by 1938 violence was being used to kill Jewish business owners or scare them into fleeing, and then turning their so called abandoned property over to new Aryan owners at little or no cost. Some Jewish owned printing firms in Germany changed hands through this process.
Aristo is a brand name for a silver chloride printing out photo paper, with a collodion or gelatin base, introduced by the American Aristo Company in 1890. The paper usually required gold toning, which produced warm purplish hues with a low gloss finish, but the color could be manipulated in other ways as well. The Aristo Company was purchased by Eastman Kodak in 1899, when it was turned into a subsidiary and renamed the General Aristo Company. Aristo paper was previously used to produce cabinet cards, but by 1903 it began being manufactured on a heavier stock to support real photo postcards. It was produced in postcard size with a pre-printed postcard back and stamp box holding the Aristo logo. Kodak later introduced self-toning versions of this paper with a pure collodion emulsion but production seems to have stopped around 1908.
An Aristotype is a photograph printed on paper photosensitized with a silver chloride gelatin emulsion.
Art Colour was a trade name used for a type of tricolor postcard issued by the firm Valentine’s during the 1940’s and 1950’s. These cards were printed in halftones consisting of red, yellow, and a medium blue.
C.T. Art Colortone or C.T. American Art Colortone, were a trade names used by the Curt Teich Company for their linen postcards that began being printed in the 1930’s. Most of these seem to consist of a black halftone printed over red, yellow, and blue dots plus an extra red or blue. They were issued as part of their A, B, and C series and their identification numbers incorporated the prefix H.
Art Deco is a decorative style, not an art movement. Its basic elements could be seen in work dating back to 1910, but it wasn’t until the Exposition Internationale des Arts Decoratifs Industriels et Modernes held in Paris in 1925 that it received international attention. Afterwards this style began to be widely implemented especially in architecture. Its projection of luxury and affluence made it popular within a society desperately trying to leave the austere years of World War One behind them. Though influenced by modern art movements, its designs were often based on classical motifs borrowed from ancient Egypt, Persia, and Native Americans that were then reduced to highly stylized geometries. This style utilized strong symmetrical and very flat ornamentation such as sharp zigzags, rounded corners, stripes, and simple sweeping curves. It romanticized the machine age by incorporating industrial forms into design and by the strong use of man-made materials. Art Deco’s popularity waned once it began to be mass-produced, thus losing its air of exclusivity. Consumer cutbacks during World War Two put an end to its use in the West, but a number of former European colonies just began using the style in the postwar years as a symbol of modernism. There were also revivals of Art Deco in graphic design during the 1960&rsquos and 1980’s. The term Art Deco was never used while the style was in fashion, being coined by the British art critic Bevis Hillier in the 1960’s. Among its many contemporary descriptions it was most often referred to as Style Moderne. Its definition continues to evolve.
Artificial Lithographic Stone
Artist Signed Card
An Artist signed card specifically refers to an illustration that has been designed for use on a postcard, which distinctly displays the artist’s name. The postcard itself is not actually signed; the original art work is signed and the signature is reproduced along with the picture. Some stretch this definition by considering any postcard containing an illustration made for postcard use to be artist signed whether there is an actual signature is on the card or not. Many artists designed thousands of cards, but they may not have signed all of them. Publishers did not always care if an unknown artist omitted a signature, and some well known artists used anonymity to obtain work beyond exclusive contractual arrangements. These cards should not be confused with art reproductions even though they may look alike.
Art Nouveau (New Art)
Art Nouveau was a major decorative art movement centered in Europe at the turn of the 20th century. While the term Art Nouveau was first associated with the symbolist influenced Belgian artists of Les XX in 1884, the name Art Nouveau as a decorative style was derived from the name of a Parisian shop, Maison de l’Art Nouveau, which promoted this type of work. As the movement spread across Europe it became known as Jugendstil in Germany, Sezessionstil in Austria, and Modernismo in Spain. Its progressive designs were first glimmered in the 1880’s rising out from the English Arts & Crafts movement. It came about as a reaction against years of historical and moral emphasis in art. After its exposure at the Universal Exposition of 1900 in Paris, and the 1902 Exposition in Turin, Italy, its popularity quickly grew. Though heavily influenced by Japonisme, the English Pre-Raphaelites, and Symbolist painters, Art Nouveau was more consistent in style. It emphasized dynamic and flowing curves inspired by the natural forms in nature from such unconventional items as insects and seaweed. The style was richly ornamental and asymmetrical. This imbued many of the objects that carried this design with a living growing presence. It was widely used in design on everything from jewelry to furniture to glassware. It was also applied to architecture where it often incorporated modern technology, inspiring wildly cast iron and glass. The Art Nouveau style had great influence on the graphic design of postcards made in Europe during their Golden Age. The end of World War One brought about a social crisis where many of the established values of the prewar age were now discredited, and Art Nouveau was too closely associated with the ideals and class that carried the world into a disastrous war. As public taste shifted, Art Nouveau faded away in favor of decorative modernism that promised a better future.
Artotype was the name given to the Albertype printing process by Josef Albert on his patent issued in the United States in 1869. Johann Babtist Obernetter would make alterations to this collotype process by creating a photosensitive emulsion with an albumen and silicate base. This meant that it need not be hardened by light, thus allowing it to be mounted on metal instead of a fragile glass plate. This substantially increased the number of prints that could be pulled from a plate. Obernetter patented this process in 1878 under the same Autotype name. Rights to this process were purchased by T.S. Lambert, W.A. Cooper, and A. Mueller who formed the Artotype Company of New York. Edward Bierstadt managed the firm, and his name appears on the work they produced. The terms collotype and autotype, were used interchangeably during the late 19th century.
Arts & Crafts Movement
The Arts & Crafts Movement was originally an English social and aesthetic movement of the late 19th century whose name derives from the Arts and Crafts Exhibition Society. It borrowed heavily from pre-industrialized times, especially from Medieval, Islamic, and Japanese design. Botanical subjects were the most popular motif often yielding designs that were multifaceted yet incorporated a simple elegance. In the face of declining rural handicrafts and a rising industrial society, John Ruskin and other writers began to call for changes. They believed a moral society depended on the skilled workers that produced creative products, not soulless objects from a machine. The Arts & Crafts Movement began as a search for a meaningful style that could stand up to Victorian moralism, but it soon took up the cause of the master craftsman, with his hand in every phase of production from beginning to end. There was much debate among the Movement’s proponents on whether mass production could create affordable art for everyone, or if it threatened individual creativity. Many of the socialist designers, inspired by the Aesthetic Movement, did not believe in a connection between morality and art, and promoted its more democratic forms. This conflict dominated the design debate into the 20th century. The movement was criticized as elitist, and its impracticality in a growing industrial society doomed it to failure. The United States imported these ideas from Britain forming an American craft movement centered in Northern California and New York State. Native designs such as the Shaker Style gave the work produced in America a simpler cleaner look. The works of the Adirondack Style, Stickley Style, Bungalow Style, Prairie Style, and Shingle Style all fall within the American Arts & Crafts Movement. While in Europe this design style evolved toward Art Nouveau, the many looks of Arts & Crafts in the United States held on to their popularity and largely remained unchanged. The style continues to be influential today. Design movements expressing similar ideals also rose independently at the same time in Russia.
Artura is a brand name for a developing out photo paper introduced by Eastman Kodak in 1905 that tended to produce greenish tones. It was produced in postcard size with a pre-printed postcard back and stamp box holding the Artura logo. In 1921 Kodak had to divest itself of this company as part of an antitrust settlement and paper production ended in 1924.
Autochrom is a term sometimes applied to postcards and prints manufactured as tinted halftones. They were an attempt to produce photo-based images in color at a time when there were no viable forms of color photography. While there was no strict palette, red, yellow, and blue were the most common colors most used, with red and blue often broken down into light and medium shades. Color was laid down in small dots or markings by retouchers in the same manner as in chromolithography, only here they were overprinted in black with a photographic halftone that served as the key plate. Most Autochromes were printed through letterpress. Louis Glaser, a pioneer in this technique, began using the process in 1884 and incorporated the term Autochrom into his logo when he registered it in 1899. He later registered the term itself to describe the palette used to print his cards. Other publishers like the Pictorial Stationary Company also used Autochrom as a trade name on their postcards. The term Autochrom eventually came to be commonly applied to any postcard made from photographic halftones printed over lithographic color. This technique is sometimes referred to as the Glaser process after it was elaborated on by Charles Frey from which it was also called the Frey process or the Glaser-Frey process. Printed Autochroms should not be confused with photographic Autochromes.
Autochromes were a type of color photographic transparency patented in 1903, and manufactured from 1907 by the Lumière Brothers. These were the first practical, and one of the few commercial means of creating color photographs during their 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. This type of emulsion was later moved from glass plates and onto film in 1932 when the Lumière Brothers created Lumicolor. It was replaced in 1938 by the even faster Filmcolor that utilized brewer’s yeast in place of potato starch, but it could not compete with Kodak’s Kodachrome introduced in 1935, and fell out of use by 1940. Autochromes could not capture all the nuances of color but they did produce subtle tonalities. Combined with its strange grainy effects, the resulting images appear to be halfway between paintings and modern photographs. Photographic Autochromes should not be confused with printed Autochroms.
Autocromotypie was a trade name sometimes used by Dr. Trenkler & Co. for their tinted halftone postcards. The term Autochrom had been in common usage to describe this process until it was registered in 1899 by Louis Glaser for the exclusive use of his company. By 1900 they were warning competitors not to use the term, which Dr. Trenkler & Co. refused to do. In 1902 Gustav Jahrig, managing director of Trenkler started a long legal battle by arguing that Glaser was not entitled to exclusive use of the term Autochrom. In the meantime he continued to use the term Autochrom as well as introducing the new term Autochomotypie to get around accusations of trademark infringement. The case went on until February of 1908 when Jahrig lost the final appeal and was ordered to pay damages.
Eastman Kodak manufactured Autographic cameras with a small door on their backs so that they could be safely opened while taking pictures to add a label to the negative. The open door would reveal an opaque red paper that could be scratched through with a supplied chrome scribe. It would then be held to light for a few seconds to expose the negative through the scratched out notations. This would appear as white lettering on the photographic print. The autographic door became a standard feature on Kodak’s Vanity Cameras. These cameras were not often used by professional photographers and they only played a minor role in the production of real photo postcards. The same effect could be easily achieved by scratching directly into a processed negative when the placement of tones in the composition was already known. This feature was patented in 1902 but was only introduced to the public in 1914.
Autogravure is an intaglio printing process based on heliogravure.
Autotype is a term coined 1868 do describe a photomechanical process that combined the traits of a collotype with carbon printing. Carbon or another pigmented colorant was placed in the gelatin emulsion at the same time it was photosensitized with potassium dichromate. After exposure to a negative, the paper emulsion is moistened and adhered to a glass or metal plate, and then the paper is removed. The unexposed gelatin is then washed away with warm water leaving the light hardened gelatin behind on the plate. The gelatin emulsion was then transferred once again onto a sheet of paper to form a finished print. A wide range of tonal values were created through the density of pigment in direct proportion to how much hardened gelatin was left behind. Since pigments are very durable, these images were sometimes referred to as permanent photographs. They were produced in a range of about fifty monochromatic colors.
Autotype Mechanical Process
In 1886 the British Autotype Printing and Publishing Company became the first firm to use collotypes in commercial printing, a method they termed the Autotype Mechanical Process. Afterwards the terms collotype and autotype were sometimes used interchangeably. This printed material should not be confused with carbon prints produced as Autotypes.
Azo was a brand name for blue light sensitive, silver chloride photo paper introduced by the Photo Materials Company in Rochester, New York in 1898. Eastman Kodak purchased the company that same year. Though much faster than collodion based papers, Azo was able to be exposed indoors under gaslight lamps (gaslight paper), but its poor light sensitivity restricted its use to contact printing rather than enlarging. Azo paper is known for its very broad tonal scale, which made it the finest paper available to produce black & white work on. This paper became the favorite of those producing real photo postcards and was widely popular among amateurs because of its ease to use. It was produced in postcard size with a pre-printed postcard back and stamp box holding the Azo logo until the 1940’s. Unmarked sheets of Azo remained in continuous production until 2005; longer than any other photo paper.