Blue Skies: A Conservation View

by Jane E. Klinger and Joan M. Walker (2019)


Photographs are ubiquitous in our daily lives, from food shots to selfies to kittens. In this digital age, hundreds of images can be easily produced and then casually deleted. Cameras are carried daily as a matter of course and have an alternative function as communication devices that would more aptly be called cell cameras rather than cell phones. Until the latter part of the twentieth century, however, photography was fully ensconced in the analog world, reliant upon a system that produced a negative from which the physical positive was printed. Both components required careful chemical processing in a darkroom in order to produce a usable negative and a high-quality print. Within this context, “instant” film products, made by Polaroid and other manufacturers, were a revelation. Suddenly, an image could be captured and magically appear in one’s hand within minutes.

Invention and Commercialization of Instant Prints

In 1948 Edwin H. Land, the visionary scientist and founder of the Polaroid Corporation, introduced the first camera and film system that produced instant prints: the Land Model 95. Land cited his young daughter’s impatience to see a photograph as soon as it was taken as his motivation to invent the instant print. The earliest systems produced only black-and-white prints; color instant film was not introduced to the market until 1963. Although all were commonly called “Polaroids,” both Kodak and Fuji entered the instant print market in the 1970s and 1980s. Beginning with the rise of digital technology in the 1990s, however, all forms of analog photography have faced a steep decline. The Polaroid Corporation filed for bankruptcy in 2001 and ceased manufacturing cameras but continued making film until 2008. When Polaroid announced it would stop production of its instant film, amateur users, artists, and photographers who were committed to analog media all decried its passing. The Impossible Project (now known as Polaroid Originals) quickly announced its formation and the goal of continuing the production of instant film in the same formats and configurations as those of the Polaroid Corporation, following the Polaroid patents.

Fujifilm has been continuously producing instant film for almost forty years, starting in Japan in 1981. Until the appearance of Polaroid Originals, Fuji made one of the few remaining pack films, called FP-100C, that could be used in the vintage Polaroid cameras. FP-100C film was popular with enthusiasts and professionals, not only because of the clarity of the print, but because the negative could be recovered, cleared, and used for making further prints. Fujifilm ceased production of FP-100C professional instant color film in 2016 but has continued production of the Instax system in multiple formats, primarily geared towards the amateur market that remains fascinated by the magic of a photograph appearing before one’s eyes.

Black-and-White Instant Prints

The Polaroid Land Model 95 camera produced finished black-and-white prints in a few minutes once the shutter was pressed. The system comprised a roll of negative paper that incorporated a light-sensitive silver halide, a positive paper with no light-sensitive component, and a developing agent. After the negative paper was exposed to light through a camera, it was pressed in direct contact with the roll of positive paper in the presence of the developing agent. The silver not used to form the negative diffused to the positive paper to form the final print. This method evolved into an integrated system featuring a self-contained film pack to expose, develop, and fix an image. Each individual film pack was enclosed in a black envelope to prevent light from fogging the components.

Cassettes of film packs were easily loaded into the camera and exposed by the consumer. While the various types of these integrated pack film systems vary in the details, they all have the negative and positive components plus a pod containing a viscous developing and stabilizing chemical reagent mixture. After exposure, the film assembly is pulled from the camera. This action causes the pod to burst, releasing the reagent. As the film passes between the rollers, the reagent spreads between the two papers, developing the negative. The negative component, pressed against the positive sheet, releases its unused silver halide, which diffuses to the positive film to produce the image. Processing continues outside the camera over several minutes (from one to ten minutes, depending on the film type) until the negative is peeled away from the positive, revealing the final silver print. Chemical reactions will continue in the photograph until the alkaline developing agent is neutralized with an acidic material, which was originally applied by hand to the print after the negative was peeled away. The coating hardened as it dried, providing a significant degree of protection of the image from physical and chemical damage.

Color Instant Prints

Polaroid introduced Polacolor, the first color instant print product, in 1963. Deceptively simple, the chemical processes required to produce an instant print in color are among the most technically advanced in the history of photographic technology. While the fundamental positive-negative concept and reagent pod with roller-transport system of Polacolor are similar to the black-and-white products, the chemistry involved is vastly more complex.

Instant color systems consist of up to twenty layers within and surrounding the negative and positive components. These layers contain all the dyes, developers, reagents, fixatives, and various polymers that are required to render a stable, color-balanced image from the light entering the camera. Diffusion of the reagent that develops the image, the reactions needed to fix the photograph, and the drying of the protective surface layer must all be carefully timed to produce a viable image without the intervention of the photographer. Simply put, the photograph as a positive print results from the diffusion and transfer of an array of image-forming components from the negative layer by the release of a developing agent. The presence of carefully designed components causes all chemical activity to start and stop at the appropriate times. When the negative is peeled away, the print comes in contact with the air, and the surface dries and hardens to form a glossy, protective coating.

In 1972, Polaroid introduced SX-70, a one-step process that did not require the negative to be peeled away. It is called an “integral film” because all the chemical components that formed the negative as well as the final image reside within a sealed plastic envelope. Because in integral film there is no separate negative, the developing reagent had to be neutralized within the plastic envelope in order to stop all the chemical reactions from continuing but still yield a lasting photograph.

Use and Conservation of Instant Prints

Instant film was marketed for use in situations where it was undesirable to have to wait for conventional film to be processed and printed, such as for passports and other identity documents. Instant films in various formats up to 20 × 24 inches and formulations producing transparent, translucent, or opaque images were manufactured for different uses. But from the beginning, Polaroid encouraged the use of instant film by artists and even developed a direct relationship with Ansel Adams to test and review instant film products. It was a relationship that lasted several years and influenced Polaroid’s research and further development of the company’s products. Other artists, including Andy Warhol, David Hockney, and Robert Mapplethorpe, became enamored of the simplicity and immediacy of the technology in creating artworks. Artists such as Robert Rauschenberg and Lucas Samaras experimented with putting their own stamp on the final image by manipulating the prints in various ways, such as unevenly coating a print in order to encourage localized deterioration or selectively applying pressure to an SX-70 to distort the image. 

With many well-known artists experimenting with instant film to produce unique works of art comes the inevitable passage of the photographs from studios to collectors and cultural institutions. Once these sensitive photographs move into the domain of the museum their preservation becomes imperative. Instead of enjoying the immediacy that made instant prints popular with artists and the general public, the museum must focus on their preservation and comply with high ethical and professional standards to ensure the longevity of the objects in its care. The chemical instability of instant prints is well documented, but comprehending their material composition and pathways of degradation is complex. Further complicating the analytical study of instant prints and their conservation is the fact that, unlike conventional color photographs, the dyes, processing chemicals, and reagents that remain in instant prints may cause unpredictable changes, such as fading.

As with traditional photographic film and prints, color instant film contains more layers than the black-and-white versions. Three of the negative image forming layers are silver halide emulsions, each sensitive to a primary color. Other associated layers contain dye developers or dye releasers in complementary colors. In addition, there are various interlayers, processing reagent layers, neutralizing and fixing layers, as well as the image receiving layer and various protective coatings. The specific compositions of the layers are proprietary formulae, further complicating the full understanding of how a given print will degrade or how the dyes may shift in value over time. Such information would greatly aid in being able to predict which conservation treatments might successfully address any deterioration.

Blue Skies at the USHMM

From 2012 to 2017, Anton Kusters used Fujifilm FP-100C peel apart instant color film for the Blue Skies Project. Because of the sensitive nature of this medium, each time the work is to be shown Kusters requires an ‘act of conservation’ by the exhibiting institution. In the case of the exhibition at the U. S. Holocaust Memorial Museum (USHMM) in 2019-2020, conservation staff decided to test the sensitivity of the photographs to the specific environmental conditions to which the work would be subjected.

A quick daylight test was performed to ascertain how quickly the prints were likely to fade. A test print was placed into a black mat board sleeve with part of the image exposed. This was mounted directly onto a south-facing window and examined periodically for any fading or color shift. Light at the window averaged 750 lux during daylight hours. After forty-four days, an easily perceptible amount of fading and color shift had occurred, confirming the light-sensitive nature of the prints and the need for further investigation (Figure 1).

Figure 1:
A test print placed into a black mat board sleeve with part of the image exposed.

Figure 2:
The exhibit case with a data logger to record temperature, relative humidity, and light levels.

In making preservation recommendations, museum professionals consider many variables, e.g. temperature, relative humidity, and light exposure, that may affect a work of art while it is being stored or on display. In order to understand the possible effects of exhibition on the photographs, two of the test prints were mounted in a small exhibit case on the wall where Blue Skies was to be displayed. Black mat board covered half of each photograph to prevent light exposure. A data logger was included within the case to record temperature, relative humidity, and light levels; readings were set to record at ten minute intervals (Figure 2). Such “real life” testing not only can indicate light sensitivity, but also may highlight the effects of variations of temperature and humidity. Testing occurred over ten weeks, from mid-August until November 2018. Recorded data showed light levels peaked at 650 lux during the brightest parts of the day, slowly dropping to 50 lux by evening. Overnight light intensity averaged 27.5 lux as only a few work lights are on in the building. The light levels then began to gradually increase at sunrise with a jump when general museum and exhibition lights turn on. Temperatures inside the case were shown to be within acceptable limits as the area is fully air conditioned. As relative humidity is not controlled in this space, it did fluctuate beyond recommended limits, as high as 65% on humid or rainy days and below 45% on cooler, drier ones. Slight color shifts were noticed by comparing the covered sections to the exposed sections of the instant prints, but no planar distortions from the fluctuations in temperature and humidity were detected, possibly due to how the prints were mounted with the mat board cover.

Microfading to Predict Color Change

While these tests provided basic practical feedback as to how the instant prints would stand up to exhibition, further information was needed to determine the fading rates and color shifts that could occur before displaying the prints by Kusters. Microfade testing (MFT) is a well-established method for predicting the behavior of museum objects, including photographs, upon exposure to light. During MFT a high-intensity light source is focused upon a very small area approximately 0.4 mm in diameter. Some of this incident light is absorbed by the object, and some is reflected, giving the object its color. The color is measured with a spectrometer that collects the reflectance spectrum in the visible range and is monitored over time to detect any changes in color caused by the light. Because the instrument’s light is intense, the microfading test only takes a few minutes. Based on the rule of reciprocity, it is generally accepted that this short period of high-intensity exposure will approximate a lower-intensity exposure over a longer time. As the potentially altered area of the object is too small to be seen by the unaided eye, MFT is considered minimally invasive and is widely used in museums, libraries, and archives.

The microfade tester used to measure the instant prints provided by the artist is configured based on the design by Whitmore et al. It consists of a 75 watt xenon arc lamp and filters that remove ultraviolet (UV) and infrared (IR) radiation. The lamp output is directed through a 0.4 mm fiber optic and is collected using a 0.6 mm fiber optic mounted in a 90° illumination/45° observation geometry. The reflectance spectrum is collected by a spectrometer in the range 400 – 700 nm every second. The spectra are converted to color values (L*, a*, and b*) and are transferred in real-time into a spreadsheet. These individual components represent grayscale value (L*) and coordinates on the two color axes that run from red to green (a*) and blue to yellow (b*). The total color difference (deltaE) is defined under the 1976 CIE L*a*b* equation using D65 illumination and 10° standard observer. Measurements are carried out for approximately five minutes; however, real-time monitoring of the deltaE value allows the operator to abort data collection and remove the high-intensity illumination from the object at any time to prevent noticeable color change. ISO Blue Wool (BW) standards on an eight-step scale are used for comparison, with BW1 fading most quickly. Objects changing more slowly than BW3 are generally considered suitable for normal museum display under carefully controlled conditions.

Microfading data were acquired for several areas on the prints supplied by the artist for testing, and the rates of color change (deltaE) were compared qualitatively to those for the ISO Blue Wool Standards. All image areas tested changed much faster than BW1; an additional non-image area in the white border measured between BW1 and BW2 (Figure 3). Specific information about the nature of the overall color change can be gained by looking at the changes in the component L*, a*, and b* values. The light blue areas of the image showed an increase in a* and a decrease in b* (Figure 4). These changes indicate that the photographs are susceptible to color shift during exposure to bright light.

Figure 3:
Microfading data for several areas on the prints, showing the rates of color change (deltaE) compared qualitatively to those for the ISO Blue Wool Standards.

Color photographs contain magenta, cyan, and yellow dyes, all of which have different photochemical reactivities. It was difficult to test the different colored dyes individually in these prints because of their uniform blue appearance. The black areas, which contain all the dyes, do not reflect enough light to produce data of sufficient quality. However, at the extreme edge of the image area on one of the test prints, there appeared to be a flaw that had an orange coloration. This edge area was tested and proved to be highly fugitive. The traces showed a sharp increase in a* and decrease in b* over less than 60 seconds (Figure 5), indicating that the magenta and yellow dyes may be even more fugitive than the cyan.

Figure 4:
Information about the nature of the overall color change in the light blue areas of the image can be gained by looking at the changes in the component L*, a*, and b* values.

Figure 5:
Information about the nature of the overall color change in the edge areas of the image can be gained by looking at the changes in the component L*, a*, and b* values.

A product information bulletin available from Fujifilm’s website provides extensive technical details about the FP-100C film, which is a peel-apart type of instant print. In brief, the final positive print consists of several backing layers and an image receiving layer containing cyan, yellow, and magenta dyes, with a clear surface layer that is intended to protect the object from both physical abrasion and ultraviolet (UV) radiation. The manufacturer states that the product exhibits “improved light-fading characteristics…allowing long-term storage under direct sunlight” due to the UV-blocking layer and a new dye stabilizer. However, it goes on to recommend, “For optimum preservation during long-term storage, keep photos in a dark, dry and well-ventilated location away from harmful gases.” Generally, recognized guidelines for museum exhibition light levels for photographic materials place instant prints in the “very light-sensitive” category and recommend conservative display.


Conservators are charged with the preservation of the material object. They do this by advising on best practices in making the collections available for use, recommending cautious display, thoughtful storage practices, and when necessary, addressing any damage through careful laboratory treatment. As instant prints are known to be very light sensitive, conservation staff recommended proceeding with caution. How quickly these particular prints would fade and what color shifts would occur were unknown. Such questions often necessitate working with conservation scientists who perform analyses and determine probable pathways of deterioration.

Data from the microfading tests showed how quickly both fading and a color shift could occur, especially in a space with predictably high light levels. As a result, there was concern that the public would be presented with skies that would not truly be blue. In the case of the exhibition at USHMM, the decision was then made to work with high quality reproductions on a more stable medium.

Conservators do not work in a vacuum, but as part of a team including conservation scientists, curators, and exhibition specialists.  By working collaboratively with experts from allied disciplines and institutions, as well as a thoughtful artist, the conservation team was able to strike an appropriate balance between the preservation of the original instant prints and faithfully presenting the Blue Skies Project to the public.


Jane E. Klinger is Chief Conservator of Conservation Management at the National Institute for Holocaust Documentation, United States Holocaust Memorial Museum. She is also a Coremans Fellow of the Preservation Studies Program at the University of Delaware. She earned her Masters in Conservation at Rosary College Graduate School of Fine Arts at the Villa Schifanoia in Florence, Italy.

Joan M. Walker is a conservation scientist at the National Gallery of Art, Washington, DC. She earned her PhD in Inorganic Chemistry at Indiana University.


Constance McCabe, Senior Conservator and Head of the Department of Photograph Conservation, National Gallery of Art, Washington, DC

Emily Olhoeft, Paper and Photographs Conservator, Conservation Management, National Institute for Holocaust Documentation, United States Holocaust Memorial Museum

Selected Bibliography

Sarah Freeman, Jim Drusik, Marc Harnly, and Christel Pesme, “Monitoring Photographic Materials with a Microfade Tester.” ICOM-CC 17th Triennial Conference Preprints, Melbourne, 15-19 September 2014 (Paris, France, 2014).

Fuji Photo Film Co., Ltd., Fuji Instant Color Film New FP-100C/FP-100C Silk, (9 December 2019).

Shinsaku Fujita, Organic Chemistry of Photography (Berlin, Germany, 2004).

Bertrand Lavédrine, A Guide to the Preventive Conservation of Photograph Collections (Los Angeles, California, 2003).

Constance McCabe, ed., Coatings on Photographs: Materials, Techniques, and Conservation (Washington, D. C., 2005).

Debra Hess Norris and Jennifer Jae Guierrez, eds., Issues in the Conservation of Photographs (Los Angeles, California, 2010).

Sylvie Pénichon, Twentieth Century Color Photographs: Identification and Care (Los Angeles, California, 2013).

Ronald D. Theys and George Sosnovsky, “Chemistry and Processes of Color Photography.” Chemical Reviews 97, no. 1 (1997): 83-132.

Sarah Wagner, Constance McCabe, and Barbara Lemmen, “Guidelines for Exhibition Light Levels for Photographs.” Topics in Photographic Preservation 9 (2001): 127-128.

Paul M. Whitmore, Xun Pan, and Catherine Bailie, “Predicting the Fading of Objects: Identification of Fugitive Colorants Through Nondestructive Lightfastness Measurements.” Journal of the American Institute for Conservation 38, no. 3 (1999): 395-409.

Henry Wilhelm, The Permanence and Care of Color Photographs: Traditional and Digital Color Prints, Color Negatives, Slides, and Motion Pictures (Grinnell, Iowa, 1993). (5 December 2019).

This essay originally appeared in the published monograph “1078 Blue Skies / 4432 Days” by Anton Kusters