Using UV Photography in the Conservation Treatment of Rare Judaica
Today’s post was written by Shannon Mulshine, graduate student assistant at NYU Libraries’ Barbara Goldsmith Book and Paper Conservation Laboratory and second-year graduate student at the NYU Institute of Fine Arts Conservation Center.
The book pictured above is a Hebrew text, The Response of Molin, printed in Venice in 1549. It is part of the Mitchell M. Kaplan collection of Rare Hebraica and Judaica in NYU’s Fales Library and Special Collections and was selected by Fales curators for conservation treatment. Around 75 volumes from the collection have recently been surveyed and surface cleaned in preparation for cataloguing, which will facilitate public access to these interesting works. Many of the books, printed in the 16th and 17th centuries, still possess original or contemporary binding material, but were repaired at some point with the addition of more modern materials. Their composite structures are intriguing to a student of bookbinding like myself.
However, the structures are not our primary concern in the lab. At some point, the bindings of the books had been covered in heavy black cloth pressure-sensitive tape. Today the tape adhesive is cross-linked and failing. The cloth carrier is peeling, damaging the brittle covering material, and leaving adhesive behind on the books. The lifting tape has a tendency to get caught on or scratch neighboring books. Considering the size of the collection, and their low circulation as currently uncatalogued items, comprehensive item-level treatment could not be justified at this time. Instead, custom-fitted boxes were chosen as an adequate, economical solution to preserving the collection for now.
The Response of Molin (also referred to as Kaplan 50) was an exception. Its stiff vellum binding interested us, because it was in good condition, and appeared, unlike much of the collection, unmodified. The tape carrier was gone, but it had left behind a hard, thick, white residue on the vellum and pastedowns, likely a rubber-based adhesive. It was my assignment to determine how to remove the adhesive in a timely manner in a way that was safe for the book and myself. Mechanical methods, and spit cleaning, were tested and determined to be too time-consuming. Knowing the sensitivity of parchment to moisture, I turned to poulticing as a means to control the application of moisture to the treatment area, while I attempted to swell the adhesive enough to easily remove it with cotton swabs. Opting for milder solvents, I found that a 2% Klucel G in ethanol poultice would do the trick. Once I’d determined the ideal application time, the treatment proceeded quite smoothly.
UV visible fluorescence photographs were taken to help assess the extent of the adhesive removal. Examination in UV can yield a lot of information if you know how to interpret it. Different colors of visible fluorescence can help to identify adhesives and pigments. For this treatment, we used UV as a tool to help us see in a new way. We did not identify our adhesive, but because components of it fluoresced more than the paper pastedowns, we were able to compare how much of it remained after treatment a little more efficiently than we could in visible light. The removal of the fluorescing components is virtually complete (figure 2).
An exception is beneath the inscriptions “P – 50” (figure 3). Pretreatment spot testing for solubility indicated that the writing medium was copy pencil. Any exposure to water or alcohol would dissolve its aniline dye component and cause bright purple staining. To avoid this destructive change, the adhesive over the inscriptions was reduced mechanically with a scalpel. Under UV, fluorescing material appears above the inscriptions, where it is not evident in the visible light photograph. The UV visible fluorescence photographs accentuate what we may miss in visible light, and serve as a map of the efficacy of our treatment.
Interestingly, since the vellum fluoresced more than or about the same as the adhesive, UV light was not as helpful when examining the covers. We did not predict this result, but understood that the materials examined would limit the information it could yield. We did discover a surprise however…I had never noticed the inscriptions on the front cover before they were accentuated in the UV photographs, due to their greater absorption of UV light compared to the vellum (figure 4)!
We’re excited that the Kaplan collection is being catalogued and will soon be available for teaching and research. This project has better prepared the volumes for storage, retrieval, and use. More in-depth treatments as discussed here restore integrity to the books, and prevent further deterioration of valuable information. Kaplan 50’s endleaves were also mended for iron gall ink corrosion. The final result is a more approachable, and quite attractive binding, with a restored sense of authenticity and evidence of good care.