Color Screen Processes

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Page Information	Page Information
Date initiated 	January 2012
Contributors 	Luisa Casella, Tatiana Cole
__TOC__
== Historical Introduction and Principles ==
Autochromes are color photographic materials on a transparent support and a type of additive color screen plate. Color screen plates were the first commercially successful color photographic materials, with autochrome being the most common.
Color screen processes include in their structure a layer composed of red, green and blue light filtering components and a positive photographic image layer on a transparent support. The filters in contact with the positive image allow to see, by projection or against a light source, a full color image, following the additive color theory.
A demonstration of Thomas Young’s 1802 principle of color perception was made by James Clerk Maxwell, working with photographer Thomas Sutton in a 1861 experiment where the Scottish tartan ribbon was photographically recorded through separate red, blue and green filters and then the three separation monochrome images obtained were projected through the filter colors that created them, resulting in a full color image. 
In 1868, by Louis Ducos Du Hauron described the additive screen color system by envisioning capturing a photographic image through a screen covered by alternating patterns of red, yellow and blue lines.
Development of a successful photographic color process depended on the introduction of panchromatic silver halide emulsions. Before that, silver halide photographic emulsions had reduced spectral sensitivity, notably the wet-collodion process, mostly registering the blue region of the visible spectrum. These emulsions can be referred to as orthochromatic emulsions. With the 1873 discovery by Herman Vogel of the sensitizing effect of adding dyes to photographic emulsions, the range of spectral sensitivity was gradually expanded. A fully panchromatic emulsion wasn’t commercialized until 1906 (Penichon, p.17).
The first color screen processes were the Joly Colour (1896-1900) and McDonough (1897-1900). The Autochrome was invented in 1903 by Louis Lumière and patented by the Lumière Brothers in 1904. Autochrome were produced from 1907 to 1935 and were the most commercially successful color screen process and more commonly found in collections.
==Process and Identification==
Additive color screen processes have a laminar structure that includes a transparent support (glass or plastic), a color screen layer and a photographic emulsion composed of metallic silver dispersed in a gelatin binder. Numerous dyes were used to create the color screen elements that can be composed of potato scratch, gum arabic, gelatin, collodion or celluloid. Color screen processes can be better understood and organized following the diagram published in Pénichon, after Sebastian Dobrusskin (2013, pages 67-68). The diagram organizes these processes in those using a separate system, where the filter layer is not an integral part of the final product, and those using combined systems. They can be further organized in glass-supported (earlier) and film-supported (later) materials. For the latter, only combined systems were developed. 
Color screen plates can be distinguished by examination under magnification using a loupe or a microscope, in transmitted light. Some processes may also include brand name printing or characteristic presentation aspects that may help with identification. The color screen can have a regular or a random pattern. Regular patterns can be distinguished by the color, shape and design of the sequence of lines, quadrilaterals or circles. Random patterns are composed of colored particles mixed to create a neutral gray dusted onto a screen and can include black powder to fill gaps between color grains.
===Glass support - Separate System===
====Structure and general process====
In separate systems, a taking screen was used and a viewing screen that had to be in register for correct alignment of the final image. This separation allowed for a faster shutter time as the taking screen was less saturated in color than the viewing screen, allowing for more light to reach the photographic emulsion. The camera was loaded with the photographic image facing the taking screen in a frame. The plate was processed separately from the screen and a negative was produced (although reversal processing was possible). The negative was printed by contact with a second panchromatic plate, allowing for duplicates of the same images to be printed. The monochrome transparency was assembled in contact and in registration with the viewing screen.
Although these allowed faster exposure times and making more than one copy, the structure created issues of registration and parallax effect could be observed. 
====Types/ brand names====
*Joly Colour Screen (1896 - 1900)
*McDonough Plates (1897 - 1900)
*Thames Colour Screen (1908 - 1910)
*Dufay Dioptichrome (1909 - 1910)
*Paget Color Screen (1913 - ca. 1922)
*Duplex Screen Plate (1926 - ca.1928)
*Finlay Colour Plate (1929 - 1941)
*Johnsons Colour Screen (1953 - ca. 1954)
===Glass support - Combined System===
====Structure and general process====
Combined systems eliminated the risk of parallax effect, common in separated systems, as well as any registration issues. The plate was photographed in camera with the color screen towards the subject - in the case of the autochrome a yellow filter was placed in front of the lens to correct for excess sensitivity of the emulsion to blue and green wavelengths. During exposure, the light was filtered through the screen and rays of colored light passed through the filter of the same color and were blocked by the other filters. The plate underwent a first development that reduced the exposed silver halide to metallic silver without fixing (removing) the unexposed salts. The plate was immersed in a reversal bath and the lights were turned on for a few minutes, exposing the previously unexposed silver and dissolving the metallic silver that had been reduced in the first development. The plate was then rinsed and immersed in a second developing bath similar to the first resulting in a positive image, and then fixed. The final image was one of a kind and visually read as a color positive. After drying, plates could be varnished (Lumière recommended gum-dammar but for example Edward Steichen may have used Zaponlac - see Passafiume 2005) and sealed against a cover glass, commonly using black tape (gummed or heat-set).
====Types/ brand names====
*Lumière Autochrome (1907 - 1934)
*Thames Colour Plate (1909 - 1934)
*Omnicolore (1909 - 1911)
*Dufay Dioptichrome-B Plate (1910 - 1912)
*Dufay Improved Dioptichrome-B Plate (1912 - 1914)
*Agfa Color Plate (1916 - 1923)
*New Agfa Color Plate (1923 - 1932)
*Agfacolor Plate (1932 - 1938)
*Finlaychrome (ca. 1933 - 1940)
*Agfacolor Ultra Plate (1936 - 1938)
===Film support - Combined system===
====Structure and general process====
Color screen plates on film were only produced with the combined system and have a similar structure and processing to those described for combined glass systems above. The plates could be varnished and mounted on cardboard frames or sealed between glass and, when sealed between glass, can be mistaken as having a glass support especially if the edges are hidden by binding tape. In this case, close inspection might reveal planar distortions or Newton rings where the support might be in close contact with the cover glass. PolaChrome transparencies can be distinguished from other 35mm slides by having no imprint on the edge, the image having a metallic sheen; a magenta or green iridescence on the support side when observed under fluorescent light; and a very thin support film.
====Types/ brand names====
*Krayn Line Screen (1909 - 1911)
*Krayn Color Film (1910 - 1911)
*Lignose Natural Color Film (1927 - 1928)
*Lumière Filmcolor (1931 - 1953)
*Agfacolor Film (1932 - 1934)
*Lumière Lumicolor (1933 - 1953)
*Agfacolor Ultra Film (1934 - 1941)
*Dufaycolor Film (1935 - 1958)
*Lumière Alticolor (1952 - 1955)
*PolaChrome (1983 - 2002)
==Autochrome==
The Autochrome is a unique color transparency on a glass support. 
Historical Facts
Invented: Louis Lumière, 1903. 
Patented: Lumière Brothers, 1904.
Main Period of Use: Between 1907-1935. 
Historic Practitioners: Arnold Genthe, Alfred Stieglitz, Edward Steichen, Laura Gilpin
Contemporary Practitioners: Frederic Mocellin
=== Identification Characteristics===
Image material: Translucent potato starch grains dyed red-orange, blue-violet, or green, between two layers of varnish, as well as metallic silver image particles. 
Binder: Varnish layers and gelatin layer. 
Support: Glass ranging in size from 4.5x10.5cm to 18x30cm
Analysis: 
Non-Destructive - The potato starch grains are approximately 15 microns in diameter, and are visible under magnification with transmitted light. Positive identification of starch (as opposed to other color-screen filter components) can be done by using transmitted polarized light, because starch grains are birefringent.
XRF would show presence of silver. 
Destructive - FTIR would detect the protein (gelatine) and varnish layers, but GC-MS would be necessary to fully characterize them. 
=== Process Overview===
The support was a glass pane that carefully selected to not include defects. After being cleaned with a strong acid or alkali solution, the glass was coated with a first varnish composed of dammar and natural rubber that remained sticky. The potato starch grains used for the screen were chosen due to their capacity to absorb dyes, their transparency and the ability to select them into an average of 15 micron size by water separation methods. The granules were then dyed in three groups: for the red-orange filter Erythrosine, Rose Bengal and Tartrazine were used; for the green filter Patent Blue and Tartrazine; for the blue-violet filter: Crystal Violet and Setoglaucine. The dyes remained the same from 1907 to1935, the entire period of production. After creating the separate color granules, they were combined in a mixture to achieve a neutral gray, and the ratio had to be adjusted visually as the dye process resulted in some variations. Test plates were created for each batch. The blend was made mechanically in a mixer. The granules were dusted onto the first sticky varnish using a dusting machine that employed brushes. After applying the color filters, carbon powder was dusted using the same machine that would fill any interstices between the filters, and a talc “rinse“ was used to eliminate excess carbon. The screen was then compressed using a mechanical system with steel rods in a swiping motion. A second varnish was applied composed of dammar resin and nitrocellulose that had the purpose of isolating the color screen from moisture. After drying the plate was coated with the silver halide photosensitive panchromatic emulsion. The plates were then cut into the following sizes: 4.5x10.5cm, 6x9cm, 6x13cm, 9x12cm, 13x18cm, 18x24cm. Plates were wrapped divided by a paper board and sold in boxes of 4.
Photographers could then expose the plate in a regular camera. A yellow filter was added to the lens in order to compensate for the sensitivity of the emulsion of the blue/ green area of the light spectrum. The film was processed as described above for Glass Supported Combined Systems.
After processing, photographers were recommended to varnish the plates and sealed them against a cover glass. Although most photographers used gummed tape that was water-activated, this was recognized to risk causing bleeding of the dyes along the edge and a heat-set tape was recommended by manufacturers and suppliers.
Plates were exhibited withe by projection or in a variety of viewers called diascopes, or frames with hook systems to hang onto windows. Some rare and unusual display examples can be found where plates are mounted onto lampshades or screens,
===Autochromes Physical Characteristics, Inherent Defects and Deterioration===
In order to describe and characterize the condition of autochrome plates, it is relevant to distinguish forms of deterioration from inherent defects, as well as manufacture marks and other physical elements.
The tables below characterize types of effects that can be found on autochromes and are adapted from Lavédrine 2012, pp. 202-222.
Manufacture or processing marks and finishing elements
Aspect 	Type 	Cause 	Observed by
Emulsion application flaws 	Dark spots 	gelatin accumulating around accretion during coating 	Transmitted light
Emulsion application flaws 	Cloud of tiny dark spots 	unintentional presence of dyes in emulsion 	Transmitted light
Emulsion application flaws 	Pale spots 	Presence or air bubbles in emulsion during coating 	Transmitted light
Emulsion application flaws 	Linear bands 	Inconsistent emulsion thickness 	Transmitted light
Emulsion application flaws 	Other: pale/ dark tails and comets 	Pinpoint spots in emulsion layer 	Transmitted light
Lines, streaks, stripes or in 2nd varnish	Linear bands on surface 	Coating machine 	Reflected and transmitted light
Lines, waves, stripes in color screen 	Linear bands on color screen 	Pressing step used to increase screen grain transparency 	Transmitted light
Faults in glass 	Bubbles, waves, reliefs, depressions, pinholes 	Faults in glass sheet formation or polishing 	Reflected light
Retouching 	Spot toning; heightening; repairs; additions 	Retouching of areas of faults or stains. Often black ink is applied to cover green stains; graphite often used to increase contrast; color retouching was used to enhance pale colors	Reflected and transmitted light
Partially processed plates 	“AT”, plaques `a terminer (term created at the Albert Kahn Museum); cloudy, milky, weak, yellow-orange color tone	Plates only underwent 1st development step (negative formation) and bleaching (unexposed silver is removed) but not redevelopment step likely to save time 	Transmitted light
Paper mats 	Round, rectangular or oval paper mats, masks 	Cutout paper or cardboard mats were adhered to the image layer as form of presentation or as a spacer from cover glass 	Reflected and transmitted light
Folds 	Folds, wrinkles, creases 	Gelatin swelling due to high temperature of processing baths separates from other layers and dries distorted 	Transmitted light
Forms of deterioration
Aspect 	Type 	Cause 	Observed by
Glass deterioration 	Scratches, cracks, breaks, losses 	Poor handling or storage 	Reflected and transmitted light
Glass deterioration 	Crizzling, weeping, hazy, milky 	Glass deterioration mechanisms (silica migrates out of the matrix to the surface of the glass affecting the crystalline structure) 	Reflected and transmitted light
Mold 	Mold or fungus, spores, surface accretions, white wooly surface accretions 	Poor storage conditions including combined elevated humidity and temperature 	Reflected light
Redox spots 	Redox blemishes, orange spots, bronzing; in unvarnished plates correspond to silver mirroring spots 	Oxidation of filamentary silver image particles 	Reflected and transmitted light
Silver mirroring 	Mirroring, silvering-out; silver ion diffusion; surface silver deposition. Only appears on unvarnished plates and is more extreme if unsealed 	Oxidation-migration-reduction of silver image particles 	Reflected light
Staining 	Staining, silver image yellowing, oxidative staining, sulfiding 	Could be caused during processing (residual fixer) or as a result of exposure to atmospheric pollutants over time 	Transmitted light
Dye fading 	Dye fading 	Dyes in color screen are susceptible to light fading, particularly blue-violet; reaction is accelerated by high humidity 	Transmitted light
Heat damage 	Cracks, delamination, fading, gelatin shrinkage and separation from color screen; more severe at center of plate 	Projection of 9x12cm plates using arc lamps that generated high heat 	Reflected and transmitted light
Adhesion to cover glass 	Adhesion to cover glass, Blocking 	Can be caused as a result of poor processing (sealing before plate was dry), projection or over time as a result of excessive moisture within package 	Transmitted light
Bleeding pf dyes 	Green stains, leaching (green grains have the most soluble dyes) 	Direct moisture such as water damage in contact with color screen; can be caused during processing due to tiny perforations in or edges of 2nd varnish and gelatin layers;	Transmitted light
Delamination 	Lifting, exfoliation, separation between layers (causing loss of color registration) or from glass, more likely along edges; especially common in plates without final varnish	Fluctuations in RH and temperature; can also be a result of manufacture defect in first varnish 	Reflected light
Image layer scratches and cracks	Scratches, cracks, abrasions 	Mechanical abrasion of layers (scratches); internal tensions between layers (cracks) due to RH and temperature fluctuations 	Reflected and transmitted light
Image layer losses 	Losses 	Poor handling following layer delamination 	Reflected and transmitted light
Crystals in varnish layer 	Accretions, hazy cloud, can be associated with glass deterioration when observed from glass support side 	Glass deterioration crystals trapped between support and first varnish; crystals on second varnish mechanism is not yet understood 	Reflected light
=== Conservation and Treatment ===
Treatment procedures for autochrome plates are generally limited to stabilization of the glass components (support and cover glass) by placing them against one or between two additional glasses and binding them with tape (commonly Filmoplast P90, but also aluminum framer's tape or 3M 850 clear tape); surface cleaning using air bulb; and stabilization of delaminating image layer (Waldthausen et. al. 2001).
Conservation treatments described in the literature include glass surface cleaning, image layer consolidation (Waldthausen and Lavedrine, Hoffman, Muller and Passafiume) and resealing. 
The image surface is very sensitive to abrasion by contact so cleaning with a brush or cotton should be avoided.
====Surface Cleaning====
Surface cleaning of the glass support and cover glass of autochromes can be done using methods similar to other glass cleaning using distilled water or water:ethanol (50:50) in cotton. A microfiber cloth can be used as a last buffing step. Before cleaning, carefully inspect the plate for hairline cracks as even small pressure can cause those to break.
For plates without a cover glass: work over a smooth, clean blotter and make sure the plate is not moved during cleaning so as not to cause abrasion; take extreme care to avoid any moisture reaching the edge of the plate which would risk causing bleeding of the dyes.
For sealed plates, take great care not to wet sealing tape as it can either cause adhesive to dissolve or the moisture can be absorbed and migrate to the color screen layer, causing dye migration.
====Image Layer Consolidation====
Clara von Waldthausen first researched and developed a method whereby plates showing delamination can be consolidated with solvent vapors (Waldthausen and Lavédrine, 2002). This method uses either xylene or toluene placed in a vapor chamber created with a glass tray and glass cover. 
Note: Waldthausen preferred using toluene as it successfully reacted with all varnishes but Muller (2006) preferred using xylene due to its lower toxicity, although it may possibly not be successfully reacting with the second varnish. Please note that this method is appropriate when the final varnish used is the gum dammar type recommended by Lumière and a celluloid varnish such as Zaponlac used by Edward Steichen would require a different protocol (Passafiume 2005, p.318). Maud Blanc (Blanc 2007) reported that, for Filmcolor (Lumière later product on a cellulose nitrate support), toluene vapors alone were not successful; instead, Blanc used toluene:acetone (50:50) vapors and was able to reattach delamination after 30 minutes in vapor chamber.
Working in the fume hood, the solvent is placed in petri dishes or containers around the object that should be lifted inside the chamber (placed over small weights or containers). A glass cover is placed over the tray. The RH for this treatment should be around 45% and, if needed, a container with water or soaked blotter can be placed inside the chamber (Passafiume 2005). The duration of exposure to the vapor depends on concentration and can be gauged by testing (Passafiume mentions 3 hours in the chamber). 
Once the varnish becomes tacky (reported times vary), the object is placed over a light table to ensure correct placement of the image and the layers can be burnished with a teflon folder over silicone release mylar and are adhered to the support. As with cleaning, the plate should be inspected for hairline cracks to prevent applying excessive pressure to those areas and risk breakage. This method results in an increase in color saturation overall and this needs to be acknowledged and taken into consideration as an effect of the treatment. Due to this increase in saturation, Waldhausen discourages the use of localized a solvent chamber (using for example a small beaker with paper soaked in the solvent or soaked cotton ball and paper wedged onto its bottom and placed over the area) as it would leave a ring; however, Passafiume employed this localized method, after the overall treatment in chamber to reapply two fragments, by applying a chamber for 5 minutes and then burnishing. Possibly because the object had already undergone increased saturation in the first treatment, the localized area treated a second time did not show a difference.
Waldhausen strongly states that direct application of solvent should not be employed. Muller (2006), on the other hand, found that the chamber method was not effective and applied the solvent (xylene) to the support with a small brush and then burnished the image layer onto the support. 
It is important to let the solvent offgas fully in the fume hood before resealing the plate (for several days, and as long as there is a solvent odor on the plate).
====Glass Replacement/ Addition of Cover Glass and Re-sealing====
Glass elements in the autochrome are often cracked or broken. A broken cover glass can be replaced whereas a broken or cracked glass support can be stabilized by sealing against an additional glass plate.
Original sealing tapes may be removed. Although the Lumière commercialized a heat-activated tape, oftentimes photographers used gummed tapes with water-based adhesives. Heat activated adhesives can often be mechanically removed with a thin spatula such as a Caselli. Tapes with water-soluble adhesives can be lifted using a methylcellulose poultice, rigid gel block or gentler water-delivery methods such as a gore-tex sandwich, damp blotter/tek-wipe/ evolon etc. over hollytex or directly applied to the paper tape on the glass side. Along the edges of the autochrome, great care has to be taken not to expose the color screen layer to moisture that can solubilize the dyes or cause mechanically tensions due to swelling of the gelatin layer. Also note that the image layer may be adhered to the original sealing plate and great care has to be employed at the separation moment to avoid pulling the image layer if attached to the tape.
After surface cleaning the autochrome image layer with air, using a bulb, accretions can be mechanically lifted using a micro-tweezer, preferably under magnification.
The possibility of adding a spacer to protect the image layer from pressure against the cover glass can be considered. The arguments against adding a spacer are: it is not historically accurate; a mylar spacer can cut or otherwise mechanically harm the image layer; a paper spacer can act as a moisture trap within the package.
The package can be sealed with a variety of tapes. The original tape can be salvaged, humidified and flattened and reattached using various adhesives - heat-set adhesives such as Beva 371 Film, although applying what to the original autochrome poses various risks of heat damage; double sided 3M tape; solvent reactivated adhesive. Other tapes that can be used are: toned Filmoplast P90; clear tape with acrylic adhesive such as Permacel JLar or 3M 850; toned aluminum framers tape; custom-made tapes. One option might also be the use of a clear pressure-sensitive tape over which a toned paper tape is applied, which will create an impermeable seal (plastic clear tape) and have the historic visual appearance (toned paper tape).
Although not described in the literature, a barrier strip can be added along the center of the adhesive tape where the plates join, to protect the edges of the image layer from touching and potentially adhering to the adhesive. Possible materials for this are mylar, polyethylene strips or aluminum foil, or even the same material used to bind (e.g. Filmoplast) against itself.
One final consideration is the method of sealing. Historically, strips were sold to heat seal autochrome plates in 4 strips. But following Hanako Murata’s research on sealing tapes for daguerreotypes, a continuous strip method would likely provide a better seal.
There is no known published research on methods to stabilize autochromes with shattered supports that cannot be stabilized solely by sealing between two secondary glass supports. Attempting to adhere the shards would pose many risks to the image layer due to the solubility of the various components to a wide array of solvents.
=== Housing and Storage===
====Environment====
Storage recommendations for color screen plates are limited light exposure, relative humidity (RH) between 35% and 45% (+/-5%), temperature under 70F (21C), ideally 64F(18C). The benefits of cool or cold storage (under 54F/ 12C) have not been established and the agreement has been that they pose risk of mechanical stress between layers.
Color screen plates should be protected from light exposure and from excessive fluctuations in RH and temp, particularly plates that do not have a final varnish coating, applied after processing, and plates without a cover glass. Very low RH increases risk of delamination between hydrophilic (gelatin) and hydrophobic (varnishes) layers due to dimensional variations and consequent dimensional stress. Sustained high RH can negatively affect the color screen causing migration of dyes.
====Housing Materials====
If plates are not sealed against a cover glass, particularly if unvarnished, an argument can be made for adding a cover as a protection against abrasion, surface grime and some modulation of environmental conditions.
Similarly to other glass supported photographs, color screen plates can be housed in 4-flap paper envelopes and in mat board or other boxes that passed the Photographic Activity Test (PAT). Smaller dimensions (up to 9x12cm) can be stored vertically, in small boxes to avoid excessive weight and in collections guidelines should state maximum number per box. Excess space inside a box can be filled with mat board or archival foam to prevent jostling of plates inside the box during handling. Larger plates can be stored horizontally and in boxes - in this case the number of plates stacked should be 5 or less. Spacer methods can be devised in this case to reduce pressure on the lower plates. Some collections house plates without individual housing, inside boxes with slots that allow sliding plates in horizontally. In this case, care has to be taken during sliding the plates in and out to prevent abrading the sealing tape or image surface.
Fine Art color screen plates can be found housed in presentation window mats with sink or spacer systems. Case-specific methods are designed to secure the plate in place and prevent it from moving inside the mat such as using magnets to close the window mat or mylar strips.
===Exhibition===
====Historic Exhibition and Viewing Methods====
Historically color screen plates were viewed either by projection using optical projectors with powerful light sources or in a variety of presentation methods such as diascopes or frames with hooks to secure to a window. A diascope is a contraption that includes a plate securing frame with a spring system that lifts it at an angle from a mirror where the image can be observed; it usually is housed in a case similar to that of a daguerreotype or other cased images. 
Some rare types of presentation can be found such as mounted onto room divider screens or lampshades. Authors such as Alfred Stieglitz used characteristic and recognizable presentation mats.
====Anoxia and Other Current Exhibition Practices====
Due to the poor light stability of the dyes present in the color screen processes, these objects are classified as extremely light-sensitive See Guidelines for Light Levels and often not exhibited, with facsimiles being displayed instead. In some cases plates are displayed using reduced light exposure by employing a timer or a light switch but this approach is risky as even ambient exhibition light will negatively affect the colorants in the screen layer.
In 2011, as part of the exhibition “Stieglitz, Steichen, Strand” at The Metropolitan Museum of Art, after research into anoxia applied to autochrome dyes showed a significant reduction in light fading in the absence of oxygen, 5 plates were exhibited for a limited period of time (7 days) sealed within anoxic packages, and in a display where the light was activated by a switch by each visitor (Casella and Sanderson, 2011). Color measurements were taken before and after exhibition and results were consistent with the research data.
===Disaster Recovery===
Autochrome plates are extremely sensitive to water damage. Exposure to water (in a flood for example) would likely cause irreversible, extensive damage due to the solubilization of dyes in the color screen. In case of water damage, plates should be immediately removed from housing, preferably opening sealed packages if water was able to penetrate them, and air dried with nothing in contact with the image layer. The image layer should be allowed to fully dry before proceeding with rehousing.
Freezing is not advised due to the risk of image layer delamination as well as of risk of mechanical damage to the glass support due to pressure of moisture in microcracks.
===Presence in Collections===
Although amateur photographers, such as the Pictorialists, were excited by the introduction of color photography, the most use of these materials and how they are often found in collections is either documentation (Albert Kahn Archives of the Planet collection; National Geographic collection; Winterthur Library collection of horticultural autochromes) or family and vernacular photography. Rare and unique examples of note are small groups of pictorialist autochromes by Alfred Stieglitz, Edward Steichen, Heinrich Kühn, Alvin Langdon Coburn, George H. Seeley that can be found at The Metropolitan Museum, George Eastman Museum, the Albertina Museum and some private collections (see below).
The restriction in the ability to display and exhibit original color screen plates, combined with the rarity of fine-art or good quality examples, affect autochromes collectability (value, interest, availability in the art market).
====Selected List of Noteworthy Autochrome Collections ====
*Albert Kahn Archives of the Planet collection
*Albertina Museum 
*Art Institute of Chicago autochromes in various collections
*Bassetlaw Museum - Stephen Pegler autochromes
*Beinecke Library - Alfred Stieglitz collection autochromes
*Cinémathèque Robert-Lynen - Gervais de Courtellemont collection
*Cromer Museum - Olive Edis autochromes
*ECPAD Archive - WWI autochromes
*ENSAD-Nancy Julien Gérardin Collection
*George Eastman Museum autochromes in various collections
*History Colorado autochromes by Fred Payne Clatworthy and others
*Institut Lumière collection
*J. Paul Getty Museum Alfred Stieglitz collection autochromes
*Karel Šmirous autochromes
*Library of Congress - Arnold Genthe autochromes
*National Gallery of Art - Alfred Stieglitz Key Set
*National Geographic collection
*National Portrait Gallery - Olive Edis autochromes
*Rothschild Archive
*Société française de photographie autochrome collections
*The Metropolitan Museum of Art
*Victoria & Albert Museum - Royal Photographic Society Collection 
*Winterthur Library collection of horticultural autochromes
== Further Reading ==
===General Reference===
*Coe, Brian. Colour Photography The First Hundred Years 1840-1940. London (120B Pentonville Rd, N1 9JP): Ash and Grant Ltd., 1978.
*Coote, Jack H. The Illustrated History of Colour Photography. Surrey: Fountain Pr, 1993.
*Lavédrine, Bertrand, Jean-Paul Gandolfo, Christine Capderou, Ronan Guinée, and John P. McElhone. The Lumière Autochrome: History, Technology, and Preservation. Los Angeles: Getty Conservation Institute, 2013. pp.52-99,114-121,134-145,162-179,194-229
*Pénichon, Sylvie. Twentieth-Century Color Photographs: Identification and Care. Los Angeles, California: Getty Conservation Institute, 2013. pp.4-79.
*Šechtl & Voseček Museum of Photography exhibition "When the World Turned to Color" exhibition page - http://sechtl-vosecek.ucw.cz/en/mark_jacobs_autochrome/index.html
===Preservation, Conservation and Exhibition===
*Atelier de La Restauration et Conservation des Photographies de la Ville de Paris. “Projection D’Autochromes Des Collections de La Cinémathèque Scolaire Robert-Lynen et de La Société Française de La Photographie,” 2009. 
*Blanc, Maude. “Consolidation des Filmcolors.” Support/ Tracé, no. 7 (2007): 22–27. 
*Cartier-Bresson, Anne, and Marsha Sirven. “La Restauration Des Autochromes Gervais-Courtellemont,” 2002. www.paris-france.org/musees/arcp. 
*Casella, Luisa, and Katherine Sanderson. “Display of Alfred Stieglitz and Edward Steichen Autochrome Plates: Anoxic Sealed Package and Lighting Conditions.” Topics in Photographic Preservation Fourteen (January 1, 2011): 162. 
*Casella, Luisa, and Masahiko Tsukada. “Effects of Low-Oxygen Environments in the Light Fading of Six Dyes Present in the Autochrome Color Screen.” Journal of the American Institute for Conservation Vol. 51, no. n. 2 (20120000;(Fall/Winter)): 159–74.
*Hofmann, Christa, and Uwe Schoegl. “Heinrich Kuehn and Photography with Autochromes.” Topics in Photographic Preservation 9 (2001): 73–84. 
*Krause, Peter. “Preservation of Autochrome Plates in the Collection of the National Geographic Society.” Journal of Imaging Science 29, no. 5 (1985): 182–92. 
*Siegel, Robin. “Selecting and Testing Adhesive Tapes for Rebinding of Autochrome Plates.” Report on Testing Conducted at the National Geographic Society. National Geographic Society, January 1984. 
*Muller, Ulrike. “A Method of Consolidating Delaminated Autochrome Plates from the Photograph Collection of the Albertina Museum in Vienna.” In AICCM Symposium 2006, Conservation of Paper, Books and Photographic Materials. Post-Prints and Posters. 19-21 April 2006, 194–208. Wellington, New Zealand, 2006. 
*Passafiume, Tania. “Photography in Natural Colors: Steichen and the Autochrome Process.” In Coatings on Photographs: Materials, Techniques, and Conservation, 1st ed., 314–21. Washington, D.C: American Institute for Conservation, 2005. 
*Waldthausen, Clara c. von, and Bertrand Lavédrine. “An Investigation into a Consolidation Treatment for Flaking Autochrome Plates.” In ICOM-CC 13th Triennial Meeting , Rio de Janeiro, 22-27 September 2002, Preprints. London: James and James, 2002. 
===Material Characterization and Identification===
*Burnett, Nicholas, and Centre for Photographic Conservation. A Simple Method of Differentiating between Autochrome Plates and Agfa Colour Plates, 1992. 
*Flueckiger, Barbara. “Screen Processes - Timeline of Historical Film Colors.” Timeline of Historical Film Colors, n.d. https://filmcolors.org/cat/screen-processes/.
*Lavédrine, Bertrand, Jean-Paul Gandolfo, and Jean-Michel Subsielles. La plaque autochrome: analyses physiques et chimiques, étude de la stabilité des colorants. Vol. 1, 1993. 
=== Exhibition ===
* Fuchs, Caroline. "Anticipation and Reality: A Re-Evaluation of Autochrome Projection." PhotoResearcher, vol. 19, 2013, pp. 33–42.
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Category: Photographic Processes
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