Art Business News' guide to photographic processes.
Since then, photography has evolved radically. New processes are constantly developed and refined as old processes are obsolesced. This glossary of photographic processes explains some of the vast and varied ways photographers translate the world into prints.
Patented in 1854, the ambrotype produces images on glass. Like the earlier daguerreotype, each image is unique, made one at a time in the camera. The glass is flowed with iodized collodion, which is then sensitized by being dipped into a bath of silver nitrate and exposed in the camera while still wet. A chemical developer is used to bring out the image. Typically, the glass plate is placed in front of black material--paint, cloth or paper--to view the image.
A bromoil print begins as an overexposed silver gelatin print that is dried and then bleached to eliminate the metallic silver, resulting in a faint, ghostlike image. The bleached print is soaked in water; the gelatin absorbs that water in proportion to the dark and light areas. The artist then applies oil-based lithographic inks with brushes to restore the image in a painterly manner.
William Henry Fox Talbot coined "calotype" in 1840 for his developed-paper negative, which led to the first practical method of negative-positive printing in photography. To make a calotype, uncoated sheets of writing paper are covered with a silver nitrate solution, dried and then dipped in potassium iodide to make silver iodide. Then, the paper is floated on a mixture containing silver nitrate and gallic acid. The resulting image on the negative and the positive is often diffuse. In the 1840s, calotype negatives were themselves viewed as photographs.
Developed in the mid-1800s, carbon prints have a three-dimensional texture and are able to capture a wide range of tones, creating very beautiful and distinguishable black-and-white prints.
To make a carbon print, the photographer creates a carbon emulsion, which he uses to treat a piece of tissue. When dry, the photographer contact prints the negative onto the tissue. Light hardens the darker parts of the gelatin, making the darker parts insoluble in water. When the tissue is rinsed in water, the unhardened emulsion rinses off the brighter areas of the image, and the hardened shadow areas remain. The tissue is then adhered to a final surface, such as photographic paper or gelatin-coated watercolor paper. The difference between the raised dark areas and the flattened light areas creates a three-dimensional relief on the print.
Collodion (Wet Plate) on Glass Negative
Collodion is widely used to generate negatives but is also employed to produce positives (see ambrotypes and tintypes). As a negative process, a piece of clear glass is coated with a thin layer of iodized collodion. The coated plate is bathed in a silver solution to make it light-sensitive. After this, the still-wet plate must be immediately exposed in a camera. The exposure needs to be finished before the collodion on the plate has time to dry--thus the name "wet plate."
After development and fixing, the negative can be printed on any material. In the 19th century, most wet-plate negatives were used to make prints on albumen paper, but the whites of the image generally lack the yellowish cast of albumen prints. Vintage collodion prints are difficult to distinguish from other silver prints made circa 1890 to 1910 and usually require testing by a trained conservator to identify with certainty.
Cyanotypes and Chrysotypes
In 1842, astronomer Sir John Herschel invented the chrysotype, which produces images in collodial gold, as well as the more popular cyanotype process, which results in brilliant blue images. For cyanotypes, paper is coated with an iron salts solution (rather than silver compounds) to produce a light-sensitive substrate. An object or negative is placed in contact with this paper and then printed out through exposure to sunlight, not chemicals. Washing in water fixes the image in a bright "Prussian blue" or cyan tone.
Gum Bichromate Prints
Invented in the 1850s, gum bichromate printing was popularized at the end of the 19th century by the Photo-Secessionists, who liked how the images resembled tonal watercolors and charcoal drawings. A solution of pigment, gum arabic and potassium bichromate is coated on paper and dried. Then, the paper is exposed to light in contact with a negative. Gum bichromate hardens in light, so where the negative is dark and opaque, less light hits the paper and the material doesn't harden. The gum is then washed away.
William Henry Fox Talbot's first photographic experiments in the 1830s did not involve a camera. He made salt prints by placing lace, leaves and other objects on fight-sensitive paper and exposing the paper to the sun. Where the object blocks the light, the paper remains white.
Photographers and book publishers used photogravures to reproduce photographs in the 1890s to 1920s. Photogravures are often composed of a series of lines and can frequently be found in illustrated books from the early 1900s.
Photogravures are essentially handmade printing plates that allow the consistent reproduction of a photograph. The process for making a photogravure is highly complex and involves transferring a photograph onto a hand-etched copper plate. The plate is then coated with ink and pressed onto paper. The result is an image that can be reproduced over and over again.
Polaroid prints are made in-camera and don't require chemical processing beyond letting the print process itself in the minutes following the exposure. Polaroid prints can range from tiny stickers to large prints made with a 4-by-5, 8-by-10 or 20-by-24 camera. They are one-of-a-kind photographs that cannot be easily reproduced (unlike prints from negatives or transparencies). The physical appearance of Polaroid prints can vary depending on the camera that was used to create them. They are most easily identified by the "Polaroid" name stamped on the back of the print.
Salted Paper Prints
Salted paper prints were the first type of paper print used in photography. To make a salted paper print, a piece of paper is soaked in a salt solution and then dried. The dry paper is brushed with a silver nitrate solution and dried again. Light is then projected through a negative onto the paper, and after the paper is washed and fixed, a photographic print remains.
It can be difficult to distinguish a salted paper print from an albumen print, and usually the difference is discerned by the date--prints made before the 1850s are usually salted paper prints; those made after the 1850s are generally albumen prints.
Tintypes, invented in 1856 by Hamilton Smith, begin as thin sheets of iron covered with a layer of black paint (no tin is used). This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. It is underexposed, developed in iron sulfate and fixed in cyanide. It's difficult to distinguish tintypes from ambrotypes because they are often displayed in the same types of cases.
If you're looking at an old black-and-white print with a yellow tone that was made after 1850, it may be an albumen print. Many were gold toned, and all albumen prints yellow with age. This early photographic process involved coating paper with a mixture of egg whites and light-sensitive metals. A photographic negative is then contact printed on the paper, creating a photographic print. Albumen prints gained popularity during the 1850s, when manufacturers made pre-coated albumen paper.
Cibachrome or Ilfochrome prints are known for deep, saturated colors. If you touch the print itself, it feels more like plastic than paper. That's because the base of the print is polyester.
These color prints are made in a traditional darkroom where an enlarger projects light through a slide onto Cibachrome paper. Since Ilfochrome prints are made directly from the original transparency, they tend to be of a much higher quality than prints made from an internegative (where the photographer prints the transparency onto negative film, then uses the negative to make a print).
Be extremely careful when handling these prints, as they are very fragile and scratch easily. Scratches are especially apparent on Cibachrome prints because of their high-gloss surface.
[Note: Cibachrome and Ilfochrome are different trade names for the same photographic process.]
Invented in 1839, the daguerreotype is one of the earliest photographic processes and was the first to see widespread use. A daguerreotype is printed on a sheet of copper that is coated with a thin layer of silver. The photographer places the copper plate in a camera where it captures the scene viewed through the lens. Photographers often placed finished daguerreotypes in a custom velvet case with glass over the image. Daguerreotypes often had to be viewed at an angle to see the photograph properly. If you're looking at a photograph that looks somewhat mirror-like with a metal base and a coppery or gold sheen, then you may be viewing a daguerreotype.
Silver Gelatin Prints
When you think of a black-and-white print, you probably picture a silver gelatin print. The dominant black-and-white print process for over a century, it was used by great photographers like Ansel Adams and Edward Weston. Technically speaking, silver gelatin prints are pieces of paper that are coated with gelatin mixed with light sensitive silver compound. A silver gelatin black-and-white print is made by projecting light through a negative onto the photographic paper using a traditional darkroom enlarger.
These prints are known for their ability to accurately render sharp details and an exceptional range of tones, which capture pure whites as well as deep blacks. They are available on gloss and matte surfaces, and on either fiber-based papers (which feel like paper on the back of the print) or resin-coated papers (which feel like plastic on the back of the print). Silver gelatin paper is manufactured by major companies such as Kodak and Ilford. Prints are often toned with selenium, which creates a cool tone. Selenium-toned silver gelatin prints also last longer than untoned prints.
Quadtone/Black-and-White Ink-Jet Prints
Quadtone prints are black-and-white prints made with an ink-jet printer. By replacing the printer's standard color inks with varying shades of black ink, photographers are able to make a print with a wide range of greys and blacks. These prints can be made on a variety of papers, ranging from flat matte to fine art papers.
Quadtone prints have a distinct look that is different--though just as beautiful--as black-and-white prints made in a traditional darkroom. Quadtones made on fine art papers often look a lot like platinum prints, except they have a sharper quality and a wider range of tones. If viewed closely or with a magnifying glass, you can sometimes see the grey dots that create the image. Quadtone prints have also been marketed as Piezography prints, black-and-white ink-jet prints and Iris prints.
Color Ink-Jet Prints
These digital prints are made on ink-jet printers such as Iris, Epson, Roland or Colorspan printers. These printers take information from a digital image file and print it using inks on specialized papers. The image can be printed on a variety of surfaces, including matte and glossy papers, fine art papers and canvas. If you look closely at an ink-jet print or view it with a magnifying glass, you can sometimes see a dot pattern, ink-jet prints on fine art papers or canvas are also known as giclee prints.
Type C Prints (Traditional)
These prints are made by projecting light through a color negative onto photographic paper. Traditional Type C prints are made in a traditional darkroom, using an enlarger and RA4 chemistry. They tend to have more muted colors than Cibachrome prints and Digital Type C prints. Before the advent of Digital Type C prints, this was one of the most popular color printing processes. Color prints made before the late 1990s that are not on a high-gloss paper are probably traditional Type C prints.
Type C Prints (Digital)
Digital Type C Prints are color prints made in a digital enlarger such as the Lightjet or the Chromira. They are actual photographic prints that are exposed by LCDs or lasers then processed in traditional RA4 darkroom chemistry. Photographers are gravitating to this new type of printing for a number of reasons, including ease of control over how the image looks as a print, repeatability and archivalness.
Developed in 1873, platinum prints were highly popular until the 1910s when platinum prices rose significantly and manufacturers stopped making pre-coated platinum photographic paper. But they haven't become obsolete. To make today's platinum prints, a photographer mixes the emulsion from platinum, gelatin and other ingredients, then hand coats a piece of fine art paper with the mixture. The photographer then contact prints negatives onto the platinum paper, which means the negative is put into direct contact with the paper as it is exposed by the enlarger. Since platinum prints are made on uncoated fine art papers (such as watercolor paper), the image is embedded in the fibers resulting in a softer, more painterly look than other black-and-white processes provide. They also have a flatter surface. Sometimes a less expensive metal called palladium is added to or substituted for platinum, and these prints are usually called palladium prints.
Gallery Owners: If you're interested in learning more about any of the photography mentioned in this issue, we've compiled many of the sources mentioned in one, convenient place.
* Art in Motion, www.artinmotion.com
* Autumn Color Digital Imaging, (508) 798-6612
* Blakeway Worldwide Panoramas, (952) 941-9797
* Clockwork Apple Gallery, (212) 229-1187
* Contessa Gallery, www.contessa-gallery.com
* Doni Kendig/Topaz Circle, (760) 345-0789
* Driendl Skylines, 800-347-9570
* Earth Gallery, +44 (0)1698 844430
* E-Photo Newsletter, www.iphotocentral.com
* Everlasting Images, (207) 351-3277
* Masumi Hayashi, (216) 961-0026
* International Association of Panoramic Photographers, (702) 260-4608
* iPHOTOART, www.iphotoart.com
* Library of Congress, (202) 707-6394
* Portal Publications, www.portalpublications.com
* Stephen Cohen Gallery, www.stephencohengallery.com
* Vintage Works Ltd, www.vintageworks.net
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|Author:||Seiling, Susan; Meyers, Laura|
|Publication:||Art Business News|
|Date:||Oct 1, 2003|
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