ConNext-2021

4 A preliminary Investigation into the effects of Paraloid® B72 and Renaissance™ microcrystalline wax paste on the retreatability of photodegraded East Asian Lacquerwares using Urushi. KEYWORDS: East-Asian lacquerware, retreatability, photo degradation, Paraloid B72, urushi. Photodegradation is a common deterioration phenomenon of East Asian lacquerwares. Long-term exposure causes loss of their iconic lustre due to numerous micro-cracks forming in the surfaces. Lacquerwares also become sensitive to polar solvents while originally insoluble in most solvents, which can contribute to additional damage. Conservators frequently attempt to reinstate gloss and prevent further damage by applying synthetic coatings on aged surfaces. Some conservators in the East would possibly use urushi to re-treat lacquerwares previously coated with other materials to achieve the treatment requirements. This research aims to determine whether two commonly used conservation materials, Paraloid ® B72 and Renaissance™ micro- crystalline wax paste (hereafter referred to as B72 and Renaissance™ wax), could be removed without residues, and whether a retreatment with urushi would be affected , if residues remained. An experiment was conducted to establish to which extent these two materials could be removed and to examine whether urushi could be successfully applied after removal attempts. Two naturally photodegraded lacquerware objects were prepared and coated with 2.5% (w/v) B72 in xylene and Renaissance™ wax. The coated samples were exposed to UV irradiation (9.7 W/m 2 ± 1 W/m 2 ), wavelength mainly at 352 nm for 432 hours. Subsequently, the coatings were removed using three methods – solvents on cotton swabs, an agar solvent-gel, and a solvent poultice. The cleaning results were analysed with scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) to assess if the synthetic treatment materials remained in the micro-cracks. Finally, the urushi -retreatment was applied. The results indicated that B72 could be wholly removed simply by cotton swabs dampened with xylene; therefore, it would not impede the following urushi -retreatment. Renaissance™ wax remained as residue in the micro-cracks, but this did not affect the polymerisation of urushi used in the subsequent retreatment; however, it influenced the finish appearance because the residues blanched the original lacquer surfaces. It is hoped that the results of this research would be useful for conservators to make treatment decisions for photodegraded East Asian lacquerwares, and for further research related to this conservation problem. ycliao0815[at] gmail.com