May 10, 2012
Before there were digital image files and even before there was film, photographers captured images on glass plate negatives. In the collection of the Fine Arts Museums of San Francisco there are over seventy of these glass plate negatives depicting scenes of Land’s End and old San Francisco. Discovered in the basement of the old de Young, these century-old negatives were in desperate need of cleaning and re-housing. When the negatives came into the paper conservation lab at the Legion of Honor for proper care, the labor intensive project proved a perfect opportunity for pre-program conservation student Jennifer Martinez.
Jennifer began with some sleuthing on the photographers behind the lens. With the help of historians John Freeman and John Martini, she learned that the gelatin dry-plate glass negatives were shot predominantly by the photographers (and brothers) W.C.and J.R. Billington. The Billingtons owned several studios during this time, most notably the Sutro Heights Gallery at the Land’s End Parapet, where they sold specialty views of Seal Rocks, Land’s End and the Golden Gate.
The glass plates were found housed inside an old wooden box. The negatives were in their original envelopes, which were extremely acidic and brittle.
Under the supervision of paper conservator Victoria Binder, Jennifer removed the plates from their envelopes and cleaned them with a bulb blower and soft brush to remove loose dust. Special care was taken on the delicate emulsion, which is the thin layer of image-containing gelatin attached to one side of the glass base.
Once surface dust and particles were removed, the glass surface was then cleaned with a solution of water and ethanol; remaining dirt was then removed with a lint-free cloth, leaving the glass clear and squeaky-clean.
After cleaning, each plate was placed in its own acid free four-flap envelope.
The original acidic sleeves contained important photographers’ notations, including dates, locations and exposure times, so they were placed in individual clear polyester sleeves. Together, the plates and sleeves were then stored upright in custom-made boxes lined with foam for maximum protection.
The next step in the glass plate preservation project was to digitally capture the images for the Museums’ collection database. Each negative was photographed with transmitted light and inverted in Photoshop to obtain a positive image.
The digital files allow one to explore the images and find fascinating details. In this one, for example, zooming in reveals the photographers’ advertising placards featuring sample tintypes and cabinet cards.
Some of the plates were in poor condition and required more in-depth care. One particularly rare negative depicting the foundation timbers of the Cliff House suffered from severe delamination of its emulsion layer—pieces of the thin gelatin emulsion layer had separated from the glass base, lifting and folding back on themselves. Special care was taken to flatten and secure the emulsion, which was gently relaxed using the slightest amount of moisture applied to the creases, followed by gentle pressure under weights. The emulsion was then sandwiched beneath a piece of glass and sealed along its edges with archival tape.
Though broken plates are traditionally housed flat, Jennifer looked for a storage solution that would allow the broken glass plates to be stored upright with the rest of the negatives. To prevent further cracks, it was important that the individual shards not touch. Therefore, each broken plate had a special mat cut around the individual shards, providing a buffer for the broken edges. This skeleton mat was then adhered to a back mat support on which the shards could rest.
The custom support was sandwiched between sheets of PETG plastic cut to size and sealed on its edges with archival tape. This simple and elegant package protects the vulnerable shards and provides accessibility for future study.
It couldn’t be more fitting that the negatives produced at Land’s End were conserved over one hundred years later, only a mile away at the Legion of Honor.