Insight into photographic conservation: ‘The Preservation and Conservation of Photographic Materials’

The first things that come to mind when I think about photographic materials are paper prints and flexible negatives. This is hardly surprising, as these have been the most common forms of physical photographic media since the middle of the last century. But the actual range of materials is varied, not to mention complex due to the components that comprise them, experimentations and processes about which little is known, and poor-quality processing. To understand these materials, then, we must look back to the 18th century, from the early days of the invention of photography through the development of the processes and the experimentations that accompanied it. Photography was an exciting new world that everyone wanted to be a part of, and many photographers and scientists worked together to improve its stability, speed, affordability and ease of use. It is through the hard work of people such as Sir John Hershel, Henry Talbot, Louis Daguerre, the Lumière brothers and many more, that photography was perfected and ultimately became accessible to everyone.

COURSE OUTLINE

‘The Preservation and Conservation of Photographic Materials’ at The Centre for Photographic Conservation in London focuses on early photographic materials. This seven-week course, which I attended from May to June 2017, lays the foundations for these materials’ preservation and conservation needs.

The first week explored early photographic processes, and we were given the opportunity to make our own prints, such as photogenic drawings, cyanotypes and albumen prints.

The second week focused on the identification of a wide range of photographic processes from the 1840s to the 1930s, as well as positives and negatives on a variety of supports such as paper, glass, plastics and ceramics. We were exposed to a huge amount of material, and the tips and techniques for identifying each different process were invaluable. The week finished nicely with a visit from the Royal Photographic Society’s Historical Group, who presented two conservation case studies and then led a discussion on photographs from the course participants’ personal collections.

Image 3. Visit from the Royal Photographic Society

Image 3: Visit from the Royal Photographic Society (CPC 17)

Weeks three to seven covered conservation and preservation, starting with the early processes such as collodion positives and tintypes, leading on to negatives, glass and plastic, including collodion wet plate negatives, gelatine dry plates and acetate films, and finishing with paper prints: albumen, gelatine, collodion and carbon.

During these final five weeks, alongside the teaching and practical workshops, we were tasked with writing two essays, based on objects from the Centre’s collection or aspects of photographic conservation. Mine focused on the conservation and preservation of a glass-plate stereoscope and the identification and comparison of the preservation and conservation needs of four items from the collection.

SUPPRESSED STORAGE: ENVIRONMENT AND MATERIALS

As book and paper conservators, we often have to deal with photographic materials. Storage environment and enclosure materials are key factors for the extended-term preservation of any collection, and photographic materials are no exception: these factors can either accelerate or slow down the inherent degradation process. However, photographic materials cannot be approached in the same way as book and paper archival materials, because they have very different compositions, different behaviours and higher sensitivity to environmental conditions and enclosure materials. The term ‘suppressed storage’ refers to the introduction of appropriate environmental controls for photographic materials: reducing light levels, temperature and relative humidity, and monitoring air quality.

When deciding on the best storage environment and enclosure materials, we must carry out a survey in order to:

  1. Identify the type of photographic material
  2. Know how this particular material behaves, including the environmental conditions in which it is most vulnerable
  3. Take into account its current physical and chemical condition

For example:

Collodion positive Tintype
support: glass support: metal
process: collodion & silver process: collodion & silver
inherent stability: good inherent stability: fair
vulnerable in: high temperature & RH vulnerable in: high temperature & RH
degradation: cracking back paints and silvering around the edges, breakage degradation: blistering and rusting of tin, causing emulsion to lift, scratches
Silver gelatine Albumen
support: paper support: paper
process: gelatine & silver process: albumen & silver
inherent stability: poor to good inherent stability: poor to good
vulnerable to: high temperature, high RH & light vulnerable in: high temperature and high RH & light
degradation: silver mirroring in dark areas, yellowing degradation: yellowing, fissuring

Enclosure options for photographic prints

  • Paper: a porous material that breathes, is cheaper than polyester and protects against damage from light sources. It encourages handling, however, because the enclosure must be physically opened, and it therefore puts the object at risk of damage.
  • Polyester film: protects the photograph during handling, as it is transparent and therefore does not need to be opened, and from the external environment more than paper does. It is not suitable for photographs that are mounted on a highly degraded board, as the by-products of degradation will be trapped within the enclosure and cause further damage.

As a result of this comparison exercise, we concluded that although paper is an acceptable enclosure material, polyester film storage is generally the superior option, as it better protects prints from both the environment and handling. There will always be exceptions, of course; for example, photographic material that is particularly physically and chemically unstable will need to be assessed on a case-by-case basis.

Enclosure options for broken photographic glass plates

  • Glass: used as a sandwich for broken glass plates, it is a stable material; however, it is vulnerable to physical damage, such as breakage and scratches, and can blister in high relative humidity. It is aesthetically pleasing, yet relatively costly, time consuming to prepare and heavy.
  • Acrylics: also used to sandwich broken glass plates, and a good stable material that is less heavy, time consuming, and expensive than glass. However, it is vulnerable to scratches and perhaps less aesthetically pleasing than glass. Its long-term stability is also less substantiated than that of glass, a material we know well.
  • Plastazote: often used to pad boxes or line paper four-flap enclosures, this material has not been PAT tested. Research has suggested that the dyes in black Plastazote might cause degradation in images that contain silver, whereas grey Plastazote does not contain these dyes. However, whether both types of Plastazote are stable in relation to photographic materials is still unclear, and further research and testing is needed.

Each of these three options has been used in conservation; the choice of which to go for will depend on how the item will be used and/or the time and resources available. For example, a sandwich between two pieces of glass (or acrylic) will enable the glass to have its function as a glass plate restored, but will take longer to make. On the other hand, a Plastazote sink mat will take less time to make, but it will not be easy to use the glass plate as a negative.

Enclosure options for non-broken photographic plates

For non-broken glass- and plastic-based photographs, the four-flap paper enclosures mentioned above were deemed best: the plates need the porous quality of paper, as they would be at risk of adhering to plastic enclosures.

THANK YOU

It was a privilege to spend seven weeks learning about the care of photographic materials. The practical workshops that took place alongside the teaching were especially invaluable; these averted an overload of information and helped us better understand the taught information as we put it into practice ourselves. I would like to thank Ian and Angela Moor for sharing their passion, knowledge and experience in photographic conservation with such generosity and patience, making these seven weeks a truly enjoyable time.

I came away from this course fascinated by the subject. I have been made aware of how varied and complex this field is, and despite all that I have learnt I realise I have only dipped my toes in it so far, which leaves me with a desire to learn more. There is much research to be done in this exciting field, and I look forward to seeing how it continues to grow and develop in the coming years.

Rebecca D’Ambrosio first gained a degree in Book Arts and Design, and then studied conservation at Camberwell College of Arts, London, specialising in books and archival materials and graduating in 2016. During her studies, she gained experience on conservation placements in London and Scotland and went on to work for the Wellcome Trust on a short-term contract. Alongside her passion for books, she has a growing interest in the conservation of photographic materials and completed a seven-week course at The Centre for Photographic Conservation in 2017. Rebecca is now working as a Project Conservator at Barts Health NHS Trust for the historical archive of St Mark’s Hospital.

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