by Elizabeth Martin & Martin Barnes
Since the birth of photography in 1839, both photographers and manufactures of photographic materials have been attempting to increase the longevity of photographic images and films, which are inherently chemically unstable objects.
A photograph's components are the primary support or base on which the image is printed - which can be paper, metal, glass or flexible film - and a transparent binder layer of either gelatin, albumen or collodion. Light-sensitive salts in the binder layer form the final image and can comprise metallic silver, platinum, iron compounds, pigments or organic dyes.
Each component of a photograph can deteriorate at a different rate. Not only can its constituents react with one another, but the deterioration of one constituent may act as a catalyst for the breakdown of another. Therefore it is necessary to understand the behaviour of the chemicals and the materials. By knowing how the constituents interact, the reasons why degradation of the image occurs can be understood.
The major causes of degradation of the photographic image are lack of or poor environmental control and improper processing techniques at the time of development. Acids and reducible sulphur in the mount boards and adhesives used for attaching the print are also contributory factors. Atmospheric pollutants, human interference and curiosity are also destructive.
In terms of environmental control, photographic materials should be kept in cool, dark, dry conditions. Fluctuating temperatures and humidity cause the most damage to the binder layers. Silver, although a noble metal, becomes reactive in the presence of moisture (including high relative humidity), leading to oxidation (silver corrosion). Silver ions in the image layer become mobile and migrate to alternative sites, usually to the edge of the print or glass base, a phenomenon known as a 'bloom'. In such conditions, staining, fading and image loss can also occur, the binder layers can become brittle and emulsions can break and lift up. If conditions are too damp or humid, mould or mildew growth will be encouraged: if too dry and warm the objects will be vulnerable to rodent and insect attack. Silverfish, for example find gelatin and adhesives appetising nutrients.
Airborne pollutants such as abrasive dust can cause considerable damage such as the scratching of delicate unprotected surfaces. If building works are being carried out dust can penetrate virtually any protective measures. Other pollutants include noxious fumes and gases especially from oil - based paints, varnishes, ozone (from photocopiers), ammonia and peroxides (from cleaning fluids), nicotine and car exhaust, as well as sulphurous and nitrous gases in the atmosphere. Ultraviolet rays in daylight and fluorescent light are a common source of damage. The radiation emitted can, after lengthy exposure, cause embrittlement of support and image, and will cause fading and alteration to the intensity/density of the image and to any impermanent pigments used. In terms of improper processing, if 'fixing' solutions have not been completely washed out or exhausted solutions have been used, the residual sulphur compounds will tarnish the image silver ultimately precipitating fading.
Negatives have almost always been regarded as a tool for the final product: the positive print. Photojournalists of every description would and do take reel after reel or sheet after sheet of film of one event and perhaps only select one frame for publication. If a positive was required for the next day the films would be processed as quickly as possible in order to meet a deadline. This inevitably led to sloppy processing of the negatives. Large archives exist of the work of individual photographers which suffer from this problem.
The earliest film base was cellulose nitrate (1890-1950s). Although some to this day remain in pristine condition much nitrate has severely degraded due to improper processing, inclement environment and poor storage. It may become embrittled and yellowed. Emulsions can peel and in the final stages of deterioration may become sticky which poses serious health and safety issues. When tightly packed, as in a film reel, it can self combust. It is very rare for this to happen to sheet film but cases have been recorded for 'movie' films and early x-ray films.
Cellulose acetates gradually replaced nitrate from the 1950s. (Fig. 1, acetate neg) shows a negative on a cellulose acetate base. The degradation is due not only to poor storage and lack of environmental control but also to dye couplers and fire retardants used in the finish. Deteriorating acetates give off acetic acid fumes. This is commonly known as the 'Vinegar Syndrome' on account of the resultant smell. Once unstable the condition can affect neighbouring stable materials. Although cellulose acetate is still used in some cases, polyester has gradually replaced it since the 1960s.
Up to this point the causes of deterioration have been discussed. It is evident that there are many variables to consider. Photographic materials can fade in light and can fade in the dark. The most light sensitive are salted paper prints (Fig. 2, Roger Fenton). Roger Fenton was commissioned to cover the Siege of Sebastopol during the Crimean War (1855). This was the first extensive war reportage. Fenton took his own travelling van which contained not only chemicals and equipment but also his sleeping quarters.
Using the wet collodion glass plate negative technique he recorded events as the war unfolded although under strict instructions not to include any dead bodies or scenes which might prove distressing to the general public at home. This particular image forms part of a portfolio put together by his daughter. All 132 salt prints are in relatively good condition. Fading at the edges of some of the prints is due to the ingress of light and some corners of the prints have become embrittled due to the adhesive used to secure the corners to the pages. In 1992 the Book Conservation Section of the V&A rehoused the leaves of the portfolio in a fascicule system. This means that should any leaf be required for exhibition it can be detached neatly from the binding, displayed and then returned to the fascicule. Since salted paper prints are the most vulnerable of photographic materials exhibition parameters are strict. Light levels need to be at 50 lux or below and constantly monitored. Display time is usually 12 weeks maximum and the images have rest periods in dark storage.
Since its inception there has always been a certain amount of experimentation in the field of photography. Photography in its earlier days was accused of 'imitating' art. The Daguerreotypist put the portrait miniaturist out of action. Many a skilled miniaturist, desperate for employment, ended up handcolouring daguerreotypes and ambrotypes.
Other miniaturists took advantage of the 'new Art' and made calotype portraits of their sitters, which they painted to resemble miniatures. Once enlargers and manufactured papers became available photographic studios mushroomed. Many employed professional artists to overpaint portraits. The photographic images would be printed on a variety of substrates such as card, canvas and paper. Oil paints, watercolours, pastels, crayons or aniline dyes were used for the overpainting. In adverse conditions oil paint can crack. Varnish layers can darken or yellow. Watercolours can fade and pastels and crayons can smudge or flake off.
Contemporary photographers also experiment with a wide range of materials. Some work has an intentional built in obsolescence. Some materials used are of dubious quality. These factors do not in general deter purchasers. The photographer's intent, integrity and concept are respected. David Hockney's 'joiners' are made up of many snapshots processed at the local drugstore. The snaps will fade in time and the adhesive used will become brittle so that eventually they will become parted from their secondary support.
Where photographers are still alive they may well discuss their use of materials and the best way to put a piece together with either a curator or a conservator or even both. In the case of mixed media images round discussions may be held when they start to fall apart. Should natural decay be regarded as part of the history of the object? Should the conservator/artist replace missing portions? Should a surrogate be made?
When the late Helen Chadwick was alive she often consulted the Conservator of photographs. She was meticulous in her attention to detail and provided samples of cyantoner powdered photocopies for light fastness testing. She supplied details of the adhesive she intended to use and also the fixative. The samples were subjected to two weeks testing. The results implied that the photocopies had a life span of 175 years
The materials that form the installation entitled The Oval Court (Fig. 3) are metal tiles used in the building trade, cyanpowdered photocopies made on a standard office photocopier, instant passport photos, computer generated designs on heavily loaded paper and five gilded wooden spheres. The main body of the piece is displayed at approximately 1 foot from the ground. These are the metal tiles with the photocopies laid on top together with the gilded spheres. The ensemble represents an imaginary pool filled with swimming bodies and myriad animals including fishes and birds. The paper with the computer generated designs are columns with heads based on the instant passport photos and attached to a wall overlooking the floor piece.
After the 1989 exhibition the installation was carefully packed up and stored. A custom built plan chest was made for the photocopied collages. 1998 (The Year of the Photo), saw the opening of the Canon Photography Gallery with Photography: An Independent Art and Chadwick's piece was included. Taken out of storage after 9 years any deterioration had to be assessed. There proved to be very little. The tiles were slightly scuffed at the edges, some of the collage pieces had worked loose, the gilded spheres required some cosmetic work and the loaded paper columns were discoloured at the edges.
In contrast the exhibition Breathless! Photography and Time, held in the Canon Photography Gallery in 2000, included a photographically based image that was intended to fade: Heather Ackroyd and Daniel Harvey's Mother and Child (Fig. 4). Given the theme of the exhibition we looked for artwork that would change its physical state throughout the course of the display drawing attention to the varying degrees of transience of light sensitive material. The image itself also had to deal in some way with the notion of time. Ackroyd and Harvey's work fulfilled all these criteria through an unusual medium: eschewing the use of photographic paper and chemicals they use instead organic materials, most notably grass, in which to grow their haunting and fugitive image.
A photographic negative is projected onto grass as it grows from seed on a vertical support in a dark room. The artists discovered that the blades record the shadings of the negative to produce an image with a range of tonal values equivalent to a black and white photographic print. Those areas of grass receiving most light produce chlorophyll, creating the darkest, greenest areas. Where the grass receives little or no light, it grows yellow. The positive image is printed through the natural action of photosynthesis. The artists use a special type of stay green seed developed by scientists at the Institute of Grassland and Environmental Research through a plant-breeding programme. The images can be potentially printed at any size as they are unrestricted by the standard manufactured sizes of photographic papers.
Mother and Child took about two weeks to grow. Fresh grass images fade and wilt after about two weeks so this piece was dried and de-humidified then sealed in a frame. Under light conditions of 50 lux the image gradually yellowed and faded over the twenty-eight week duration of the exhibition. Since it was impossible to preserve the image indefinitely an actual-size black and white print of the image was made for the Museum's archives. The grass version of the image has since been regrown by the artists for the exhibition Precious organised by the V&A at the Millennium Galleries, Sheffield (5 April-24 June). The piece raises interesting questions about the tradition of collecting 'in perpetuity'. While considering the preservation of artworks for posterity, museums need equally to respond to the materials, techniques and concepts of the contemporary artist.