To Treat, or Not To Treat, That is the Question: Should Silk Facing Be Removed from Manuscripts? Wang Jianlana, Kenneth R. Seddona, Susan Whitfieldb and Wong Wingyuib

a School of Chemistry and Chemical Engineering, Queen's University Belfast, BT9 5AG b The British Library, London, 96 Euston Rd, London NW1 2DB Email: [email protected]

Fig.6 Group at Ulugh-mazar. , with his dog Dash, Fig. 1 Originate state of poses in the desert during his second expedition into China manuscripts. Fig.2 Abbot Wang Yuanlu Fig. 3 Mogao Cave Fig.4 Silk Road Fig.5 Sir Aurel Stein

Adhesive samples A B C D Fig. 9 SEM image of silk with glue attached, perhaps fungi resident in it Fig. 7 Silk sample removed from a Chinese manuscript under SEM

wheat starch Glue1# BL glue 1 Glue 5# 100 100

95 95

90 90 3310 85

85 T% 3271

T% The main components extracted from The (Fig.1) are 80 80 1540 75 75 Huangbo tree, i.e. P. amurense bark are dated from the 5th to early 11th Centuries, 1003 70 1631 70 berberine, palmatine, jatrorrhizin, discovered by Wang Yuanlu (Fig.2) in 1900; 4000 3500 3000 2500 2000 1500 1000 500 4000 3500 3000 2500 2000 1500 1000 500 wavenumber, cm-1 wavenumber / cm-1 phellodendrine, magnoflorine and candicine they were sealed in Cave 17, known as the Fig. 8 Various silk samples removed from the manuscripts Fig.10 comparison of IR spectra of Fig.11 comparison of IR spectra of (Kunitomo,1964). Library Cave, in (莫高窟), see wheat starch and BL glue 1 BL glue 1 and 5 yellow silk ivory silk Fig. 3. From 1907 onward, the influx of IR spectra of silk and gauze samples 100 Infrared analysis of glue 100 Silk Gauze western explorers and treasure hunters 95 95 samples that were ushered in rival expeditions of ancient sites 90 90

T% removed from different

T% 85 along the old faded Silk Road (Fig. 4). The 85 3281 3285 scrolls manuscripts, 80 80 1027 most famous representatives who excavated 1517 2 75 1624 1624 which revealed the 75 1513 1 1005 in the ancient area include: Hungarian 70 4000 3500 3000 2500 2000 1500 1000 500 4000 3500 3000 2500 2000 1500 1000 500 wavenumber, cm-1 ingredient are different, wavelength, cm-1 Sanskrit scholar, archaeologist, Aurel Stein new silk ivory silk (a)-ivory silk (c) i.e. glue 1 is more close 100

(b)-new silk 854 (Fig.5 and Fig.6) (1852-1943), Russian

1084

1229 975

95 (c)-yellow silk (a) to pure starch based 1666 90 1448 Professor Sergei Oldenburg (1863-1934);

85 Fig.12 SEM images of glue sample adhesive, whereas glue

Intensity Swedish explorer: Sven Hedin (1865-1952);

T% 80 1053 997 5 is more close to 75 3279 1231 German team: Alberts Grunwedel (1856- 1442 70 (b) gelatine based adhesive. 65 1935) and Albert von Lecoq (1860-1930); 3 1620 4 1513 60 3000 2500 2000 1500 1000 500 4000 3500 3000 2500 2000 1500 1000 500 Table1 EDAX analysis of glue -1 Manuscript French Sinologist: . wavenumber / cm Raman shift / cm-1 Silk lining Element spectrum 1 spectrum 2 spectrum 3 spectrum 4 IR (ATR) analysis of silk samples removed from different Total: atomic atomic atomic atomic Glue weight% weight% weight% weight% manuscripts are shown in infrared spectra1-2. It revealed the 100 % % % % selection of the silk facing materials (silk and gauze) in the past were not uniform; the facing materials has undergone O K 62.04 75.87 27.90 45.15 53.20 70.48 56.70 73.25 differently after being applied with the adhesive to attach to Na K 8.69 7.39 7.88 8.87 1.82 1.68 manuscripts (some absorbed the colour from manuscripts but P K 3.72 2.35 0.00 0.00 17.47 11.96 26.38 17.60 some not). Raman spectroscopic analysis (4) of silk indicates S K 4.92 3.00 23.86 19.27 6.03 3.99 1.42 0.91 the ageing process, as well as seen in IR spectrum 3. Cl K 20.63 11.39 4.50 2.69 0.69 0.40 K K 40.36 26.72 16.97 9.20 14.82 7.83

Introduction The project in collaboration with the British Library was originally correlated to the decay of fashionable conservation technique “silk facing” or its later alternative – lamination technique, which were prevalent in conservation in the last century. Conservators were aware of the potential risk due to the yellow dye partially 1. Spraying the come off from manuscripts and absorbed by the silk facing materials; the silks became fragile and stiff over time. manuscript. However, the worst-case scenario which affect the long-term conservation of the manuscripts are adhesive, the 2. Washing the unknown receipt of glue, the ageing of glue, the moisture it has brought in to the micro-environment of the manuscript. manuscripts, the mechanical abrasion toward the scrolls of ancient manuscripts, as well as, so far there is no 3. Drying the relevant record of the provenance of silks and how the glue were prepared… manuscript. Analysis & Findings 4. Removing the • Four ordered systems (A: silk, B: adhesive, C: dye, and D: manuscript) are involved in this matrix. backing paper from • IR and Raman spectroscopy are two main non-destructive methods that have been applied to explore this topic, the manuscript. other instrumental investigations have also been performed such as SEM-EDAX, solid state NMR, HPLC, ICP-AES XRD… which helped to uncover the hidden information of these invaluable manuscripts. • The characterisation of a series of vegetable and animal derived glues emphasises the poor record-keeping of the conservation studios, moreover, the adhesive being applied to the manuscripts in the British Library were 1 2 rather follow an standard, but based on personal choices. • SEM & EDAX analysis elucidated the complex and heterogeneity of glue sample, and the morphological differences and elemental analysis suggested the impurity may come from contamination of the water that had been used in the glue-making.

• The dye-transfer phenomenon has been confirmed: the yellow dye from the manuscripts (which were dyed by water-soluble huangbo extracts) transfer to the glue paste and then to the silk materials, thus causing the discolouration of the manuscripts. Discussion & Conclusion The SEM and EDAX study lead the identification of existence of fungi and/or bacteria in the glue removed from the manuscripts, further investigation is needed to reinforce the discovery. More study is required to make a balanced decision to rewrite the destination, the conservation of the manuscripts over centuries. 3 4 REMOVE THE SILK OR NOT

• Dye transferred from manuscript 5. Removing the • Time-consuming manual process to the glue and silk deteriorated gauze • Traditional craftsman of scarcity • Mechanical abrasion from the • Massive collection in the British Library • Ageing of glue manuscript. • Ageing of silk • Cost • Other priorities overweight (?) 6. Removing the • Adhesive: hotbed for fungi glue paste from • Digitisation requirement the manuscript. Acknowledgement

The author owes a debt of gratitude to the Queen’s University Belfast, Quill, and many people in the British Library who have been kindly supporting this work. 6 References: 5 1. Wood, F., The Silk Road: Two Thousand Years in the Heart of Asia, University of California Press, 2004 2. Whitfield, S. and Library, B., The Silk Road: trade, travel, war and faith, Serindia Publications, 2004. 3. Horan, R.L., Antle, K., Collette, A.L., Huang, Y.Z., Huang, J., Moreau, J.E., Volloch, V., Kaplan, D.L., and Altman, G.H., In vitro degradation of silk fibroin, Biomaterials, 2005, 26, 3385-3393.