Gelatin Silver Developing-Out Paper Process

The autochrome process was the first viable color process for photographers. The quest for color photography had begun during the age of the daguerreotype, in the 1840s and ’50s, when at least four different methods for the application of color to black-and-white images were in use. The autochrome process—named for the plates that facilitate colorization—was the first widely successful option.

An autochrome is the result of an additive color process and is a unique photograph—a positive transparency on a glass support—with colors composed of minute grains of potato starch dyed orange, green, and blue-violet.

The autochrome process was discovered in France by the Lumière brothers, Louis (1864–1948) and Auguste (1862–1954), who patented their process on December 17, 1903, and presented it to the Académie des Sciences on May 30, 1904. The first autochrome plates were manufactured and marketed in 1907, and the plates remained in production until 1935.

The process creates a positive transparency of an image on glass. To begin, the glass plate is varnished and, while still sticky, is covered or dusted with equal portions of the three colored starches, which are then rolled flat, to make them more transparent and reduce empty space between them. A second dusting with black carbon particles fills in any gaps among the grains of starch, and then the entire plate is subjected to enormous pressure from a rolling machine. The plate receives a second coat of varnish, which, when dry, is made light sensitive with a coating of silver gelatin bromide emulsion.

To make an exposure, the plate is placed in a camera and positioned so that light passes first through the starch—which acts as a body of tiny colored filters—before reaching the emulsion. The plate is then developed using reversal chemistry, which converts the captured image from negative to positive.

Although easily accomplished by amateurs and professionals alike, the process involves several steps: developing, washing, bleaching, and fixing. After a final wash to remove all residual silver and chemicals, the one-of-a-kind final image is protected by a second piece of glass, taped on top of the emulsion.

Chromogenic prints dominated the second half of the twentieth century and are the standard photo lab–developed snapshots—which can now be printed at home from digital image files—familiar to nearly anyone who has ever owned a camera.

Based on subtractive color principles, chromogenic processing was the result of many years of research and development, by the US-based Eastman Kodak Company and by Agfa, a German company. Both began manufacturing color photographic materials in the late 1930s. Kodak introduced positive (Kodachrome) and negative (Kodacolor) film products that used color-dye-coupler technology for development and printing. Chromogenic film development and printmaking were never intended for use in the hobbyist’s or even professional photographer’s darkroom. Until chromogenic papers became available for digital Type-C prints, practically all chromogenic prints were made in photo labs.

A Kodachrome print is made from a Kodachrome color slide, a direct-positive or positive-to-positive process. The support for the print was originally a thin sheet of acetate but was changed to a fiber paper base in 1961. As mentioned earlier, both the film development and printing processes are complex and, up until 1954, could only be performed at a lab licensed by Kodak. Because of its processing requirements and the widespread transition to digital photography, manufacturing of Kodachrome was discontinued in 2009.

Kodacolor, the first color negative film introduced by Kodak, was manufactured from 1942 to 1963. Processing of the film was originally included in the price of the film, but prints had to be ordered separately.

Image stability—a print’s ability to retain its color and balance over time—has been a major shortcoming of chromogenic prints on paper; stability is particularly problematic with the negative-to-positive Kodacolor process introduced in the 1940s. Many of these prints exhibit dye fading and coupler staining, evident by yellow stains wherever magenta dye (one of the three dye layers) has faded. This is especially noticeable in highlight areas and the print’s borders, which would otherwise appear white.

Kodak introduced Type-C chromogenic paper in the 1950s. While the brand name has been officially discontinued, it lives on as a generic term for color photographic prints. Type-C prints consist of multiple layers. The bottom layer, or support, has changed over the years, employing different materials, such as fiber-based paper, resin-coated paper, and polyester plastic. The prints also contain three emulsion layers of silver halides, each sensitive to one of the primary colors of light: blue, green, and red.

After the paper has been exposed through a color negative, a silver image is formed in each layer. The introduction of a color developer—along with its dye-coupler—reduces the image to metallic silver. Further reaction with the dye coupler creates the colored dye in each layer. The process removes the silver and leaves the dyes, yielding a full-color image.

Another type of chromogenic print is a digital Type-C, or C-print. In this process, a silver-based paper is exposed to a digital file using a continuous toneprinter, such as a Lightjet, Durst Lambda, or Chromira. The file can be either an original digital photographic file or one created from an analog original. The printer uses red, green, and blue lasers to expose the paper. The image is then developed using the wet-process system. A well-known and respected brand of C-print paper is Fuji Crystal Archive.

Cibachrome, also known as Ilfochrome, is among the most stable of all color photographic print processes. The dyes reside within the emulsion layers, giving the print its characteristic color saturation. The base is a polyester triacetate, rather than fiber-based paper, which adds to the print’s longevity.

Cibachrome is a positive-to-positive photographic process based on the Gasparcolor process, created in 1933 by Bela Gaspar, a Hungarian chemist. Purchased after the merger of Ilford UK and Ciba-Geigy Photochemie of Switzerland, the process was first trademarked and marketed as Cibachrome in 1963.

Cibachrome is a dye-destruction process, meaning that bleach is used to remove the unnecessary dyes from the emulsion. Each Cibachrome print is composed of ten layers containing various combinations of light-sensitive
silver halides and dyes that are sensitive to blue, green, or red light waves. After exposure of a positive, either through an enlarger or by contact printing, the print must be developed with black-and-white developing chemicals. This step creates a silver negative image within the layers. Next, the print must be bleached. The bleaching rids the print of dyes in proportion to the amount of silver that has been developed in the previous step and produces a positive dye image in color. The print must then be fixed to prevent further development and washed to rid it of extraneous chemicals that could cause degradation.

The Cibachrome process was first marketed to professionals but was simplified over time and marketed to amateurs, particularly those seeking to make prints from their color slides. In 2011, Cibachrome/Ilfochrome products were discontinued due to waning popularity and the ascendancy of digital photography.

Photo processing became eminently portable with the invention of the dye diffusion transfer process by Edwin Land in 1947. This trademarked Polaroid-Land Process for instant photography was available only in black and white until the introduction of Polaroid Polacolor in 1962. Other companies, such as Kodak, offered similar instant products over the decades to follow.

The dye diffusion transfer process occurs within a single packet—containing chemicals, material for making a disposable negative, and material for generating the finished print. The negative consists of three silver halide layers that are sensitive to different colored light waves (red, green, and blue) and three layers of complementary colored dyes (cyan, magenta, and yellow). The positive consists of a pod of developing gel and a sheet with color emulsion layers to receive the dyes from the negative. The negative/positive packet is placed in a camera. Upon exposure, the packet is pulled out of the camera, being squeezed between two rollers. The squeezing action ruptures the developing-gel pod and spreads the chemicals between the negative and positive layers. The three phases of the process—negative development, transfer, and positive development—begin immediately and simultaneously. In approximately 60 seconds, the negative can be peeled off, revealing a positive color image.

The internal (or integral) dye diffusion transfer process, while similar, was introduced 10 years later, in 1972. The process was created by Polaroid and marketed as Polaroid SX-70. Rather than a negative and positive layer sandwiched together, all of the chemicals, the negative, the positive, and a battery for ejecting the print from the camera are included in a single unit. After the unit is exposed, it is automatically ejected from the camera without the photographer having to pull it out manually. The ejecting action breaks the gel-developer pod. This chemical reaction releases the colored dyes, which start to rise through the layers of the packet. Where the light has exposed silver halides, the dye attaches to them, creating a bond between silver and dye and forming a negative image. The remaining dyes continue up to the top layer, producing a one-of-a-kind, continuous-tone positive image. The negative remains a permanent part of the laminate structure of the unit or print.

Clarence John Laughlin (1905–1985) was an innovator in the use of photographic materials to create nonphotographic artwork.

Laughlin was born near Lake Charles, Louisiana, and lived in New Orleans for most of his life. During World War II, he worked in the photography lab of the Office of Strategic Services in Washington, D.C. There, his duties included working with the wash-off relief process, which the Kodak Company had introduced in 1935. This color photographic process was a predecessor to the dye transfer process released in 1946.

For Laughlin, these color materials were ideal tools for pushing the limits of photographic vision. The paper used in the wash-off relief process is coated with gelatin but is not light sensitive. He would puddle dyes on the paper and tilt the surface, allowing the dyes to run and mingle in unexpected ways, which Laughlin took advantage of.

In addition to using the dyes in this free-form manner, he also used a paintbrush to create specific forms and areas of color, the character of which would complement the abstract image. In some instances, Laughlin pressed the paper into the crystallized residue of the chemicals and captured their geometric shapes.

New artistic avenues for photographers opened with the development of the dye transfer process, which allows a great deal of customization and manipulation of images. The dyes produce a wide range of colors and tones, and dye transfer prints are perhaps the most archivally stable.

The dye transfer process is a subtractive-imbibition color photographic process. It employs a three-color-separation system that has been used in various applications since 1875. Two of these historic predecessors include the
dye imbibition (1925) and wash-off relief processes. Kodak released the wash-off relief process in 1935, and in 1946 a version with improvements by Louis Condax and Robert Speck entered the market, under the name Original Kodak Dye Transfer Process.

The dye transfer process is complicated. To begin, the image must be captured on three negatives, using special black-and-white panchromatic film with exposures made through red, green, and blue filters. Processing these matrices produces a gelatin relief image on each. This is the only part of the process that uses light-sensitive materials.

Each negative matrix must then be soaked in a colored acid-fixing dye corresponding to the complement of each filter—red-filter negative in cyan dye, green in magenta dye, and blue in yellow dye. An acetic acid rinse rids the film of excess dye. The matrices are then ready to be transferred to the final gelatin-coated (but not light-sensitive) support paper.

Each negative matrix is transferred separately. The matrix is placed with its emulsion against the gelatin surface of the receiving paper. The matrix film is then pressed and squeegeed to the paper surface, transferring the dyes into the paper’s gelatin coating. The three matrices, in register, produce a full color image. Ultimately, all three matrices must align in perfect registration for a successful positive image to be made.

Kodak ceased production of dye transfer products in 1993, as digital imaging technologies overtook their capacity for color control and manipulation.