Special Collections Conservators Stabilize 1,500 East Asian Rubbings for Digitization

HCL special collections conservators are working to catalog and digitize East Asian rubbings like this one from the Rübel Collection.

September 9, 2005 - A large project currently underway to catalog, digitize, and make available on VIA 1,500 East Asian rubbings from the Rübel Collection, Fine Arts Library, is making unique demands on the Harvard College Library's special collections conservators in the Weissman Preservation Center (WPC). The scope and scheduling of the work challenges conservators to exercise their organizational skills at the highest levels of practice.

The rubbings reproduce Buddhist and Daoist scriptures incised in stone stelae, cave walls, bronze vessels, jade, ceramics, and roof tiles. The original objects date from the Qin (221-207 BC) to the Ming Dynasty (1348-1644 AD) and the rubbings themselves from the Ming Dynasty to about 1940. Presented to Harvard by the scholars and collectors Langdon Warner, Lawrence Sickman, Hamilton Bell, and Adrian Rübel, they are highly esteemed, accurate, and often unique sources for scholars of Chinese history, epigraphy, and related disciplines.

The rubbings are "ink squeezes," that is, inked impressions taken from relief inscriptions by "squeezing" papers over the surfaces of the inscriptions. Thin, damp paper is placed on the hard, incised surface and tamped by brush into every depression. When the paper is almost dry, a fabric pad dipped in ink (usually black) is evenly applied over its surface. The paper in the incisions is not inked, thus the result is white writing on a black background. The opposite is true for a raised inscription, in which case a clear and exact duplicate of the text and topography of the original surface is produced in black on white. Finally, the sheet is peeled off the inscription. Characteristic of rubbings, the tissue-like paper tears and stretches when wet and often distorts as it dries, setting the stage for the conservator's work.

The Rübel rubbings range in size from six inches square to four-by-ten feet. A large size complicates handling during all stages of the FAL/WPC project. Multiple sheets of paper, quickly pasted together to take a rubbing, may never lie flat. Some rubbings have been lined with thick paper that is difficult to unfold. Others were folded into tight bundles and when they are unfolded, distortions obscure image areas and prevent complete image capture. Some larger rubbings have been folded multiple times for storage.

Each rubbing must be carefully unfolded and distinguishing features such as tears, losses, folds, creases, linings, and labels noted.

To date, about 500 small rubbings, which are easier to handle and are therefore less damaged, have been digitized. Miao-Lin Hsu, Rubbings Cataloger, Fine Arts Library, selects the objects, creates a master list in spreadsheet form, and batches together 20 or 30 rubbings of similar size and format. She sends the conservator — Debra Cuoco, Sarah Reidell, Heather Hendry, or Thea Burns — information derived from the master list and this provides a survey tool during on-site assessments. Each rubbing is carefully unfolded and distinguishing features such as tears, losses, folds, creases, linings, and labels are noted.

WPC conservators have developed selection criteria to facilitate the flow of work to the conservation lab prior to digitization. Successfully used in other projects, a system for establishing priorities and conducting conservation triage typically consists of identifying four levels of need. Objects assigned highest treatment priority (Level 1), are characterized by severe physical damage and distortions, and require treatment prior to digitization. Objects with intermediate problems (Level 2) do not require treatment before they are photographed, however they are vulnerable to further physical damage during handling. They are flagged to note that special care should be taken during handling by photographers in HCL's Imaging Services. Often, a conservator assists Imaging Services by handling brittle papers or oversized rubbings. Following digitization they are returned to the WPC lab for treatment. Low priority objects (Level 3), which typically exhibit deterioration that will not inhibit image capture or endanger the object, are digitized directly and will be mended in the future. Objects in excellent condition (Level 4) are digitized directly.

Those rubbings that are transferred to the WPC conservation lab are examined under ideal viewing conditions and on adequately large work surfaces, permitting the formulation of written treatment recommendations. The opened appearance of each rubbing is documented photographically before and after treatment.

The conservator must balance preparation for digitization with preservation of information. The flatter the rubbing, the better the digital image. The topography of the original surface, however, as captured by the ink squeeze, is a source of information for scholars. Deformations are therefore reduced to increase legibility rather than flattened. Tears and losses are repaired using Japanese paper and wheat starch paste. Labels — bits of historical evidence — are removed from the rubbings only when they are damaging the paper or obscuring inscriptions.

After treatment, small rubbings are placed in buffered paper folders; larger sheets are refolded once along an original fold line if the paper is strong, and are otherwise interleaved and rolled onto acid-free paperboard tubes. Very large and oversize rubbings are also rolled onto tubes.

On-site conservation examinations are scheduled weekly to maintain a two-month cushion between the initial curatorial selection, subsequent conservation work, and final digitization. The current throughput for conservation treatment averages 30 to 40 rubbings per month. As the more complex and larger rubbings are selected, that average may drop to below 20. The goal is to ensure that the digitization workflow is not delayed and that the project deadline (June 2006) is met.


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