Glass cinema slides
Preserving glass slides: Part 2
In 2005 the NFSA embarked on an ambitious project to digitally preserve some 10,000 glass slides in the national collection.
NFSA conservator Shingo Ishikawa and digitisation specialist Darren Weinert talk about cinema slides and their history, manufacture and preservation.
The NFSA’s glass slide preservation project
In 2005, the NFSA embarked on a major preservation project that resulted in the identification of some 10,000 culturally significant glass slides in the collection, some of which had not been accessioned. The majority are cinema slides such as the stills and intertitles from Soldiers of the Cross. There are also choreutoscope slides7 in both strip and disc shapes, song slides from the early 1900s and theatre advertisements from the early to mid-20th century.
The project has involved collaboration between curators, conservators and digitisation and storage specialists across the NFSA. Management of the project involves a number of key tasks, including:
- creating a complete listing of glass slides that had not been accessioned
- examining and creating condition reports
- cleaning and other conservation treatments as required
- entering descriptions and accessioning details into the NFSA’s collection database
- digitisation and re-housing of each slide
- rights clearance
- upload of digitised copies of each slide to the NFSA’s online collection database.
Examination and condition reporting
The slides were initially grouped by source or donor. If the source was unknown, the slide was grouped by the image content. Each group was entered onto the collection database, with a brief content description, including size and number of glass slides and a brief condition report. This list was then used by curatorial staff to determine a priority list for further preservation work. Although the listings have been completed, cleaning, accessioning and digitisation work are still underway.
Cleaning and other treatment
Once sorted and prioritised, each group of slides is sent to the Documents and Artefacts Conservation laboratory. Each slide is further examined and where necessary the condition report is amended.
At this stage any necessary treatment to stabilise or prepare the slides for digitisation is also carried out. The most common treatment required is cleaning and repair. Cleaning of the glass slides involves removal of any surface dirt, fingerprints, accretions and adhesive marks from the glass that would otherwise obscure the image when it is digitised.
Cleaning commonly involves passing a soft brush over the surface to remove light dust. Heavier soils are treated using a 1:1 water and ethanol mixture on a cotton swab. Mechanical cleaning is carried out using a scalpel blade to gently scrape away surface accretions and extraneous adhesive residues. Any loose paper or cloth tape is re-adhered to the glass. If any tape is missing or the glass is loose, gummed hinging paper is used to replace the missing tape.
If the base (the component that holds the image) is cracked or broken, then the base glass is sandwiched with a layer of glass cut to the same size and the whole object is bound together with gummed paper tape. Gummed paper tape is made of buffered paper and a water activated adhesive that holds well to the glass components. If a slide has a damaged cover glass but the base and image are intact, then only the cover glass is replaced.
The focus at this stage of the project is accessioning, digitisation and rehousing. Only the minimal amount of treatment necessary for the object to be safely handled and digitised is carried out. Any glass slide that requires a more advanced conservation treatment is noted in our database for future treatment. Regular condition checks are included as part of a cyclic maintenance program.
Examples of damaged glass slides
7 The choreutoscope, a precursor to motion pictures, used magic lantern slides. Each slide contained six separate pictures depicting a slightly different stage in a simple movement. The pictures were projected in rapid succession to give the impression of movement.