Studies in Conservation ISSN: 0039-3630 (Print) 2047-0584 (Online) Journal homepage: http://www.tandfonline.com/loi/ysic20 Some observations on the composition of Chinese lacquer Arlen Heginbotham, Julie Chang (張倚竹), Herant Khanjian & Michael R. Schilling To cite this article: Arlen Heginbotham, Julie Chang (張倚竹), Herant Khanjian & Michael R. Schilling (2016) Some observations on the composition of Chinese lacquer, Studies in Conservation, 61:sup3, 28-37, DOI: 10.1080/00393630.2016.1230979 To link to this article: https://doi.org/10.1080/00393630.2016.1230979 © 2016 The J. Paul Getty Trust. Published online: 15 Dec 2016. Submit your article to this journal Article views: 946 View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ysic20 Supplementary issue paper Some observations on the composition of Chinese lacquer Arlen Heginbotham1, Julie Chang (張倚竹)2, Herant Khanjian3, Michael R. Schilling3 1The J. Paul Getty Museum, Los Angeles, CA, USA, 2University College London, UK, 3The Getty Conservation Institute, Los Angeles, CA, USA This paper summarizes the various information that has been gathered in recent years at the J. Paul Getty Museum and Getty Conservation Institute with regard to the organic constituents of Chinese lacquer formulations. While this summary of materials is by no means comprehensive or complete, it captures the current state of the authors’ knowledge, with the information itself and the bibliography intended to serve as a useful foundation from which further research may proceed. Considerable advances have been made in the last decade in the technique of pyrolysis-gas chromatography–mass spectrometry with thermally assisted hydrolysis and methylation using tetramethylammonium hydroxide and in subsequent data interpretation methodologies. These have dramatically improved the sensitivity and specificity of organic analysis. Perhaps equally important, these methodologies are allowing researchers to collaborate much more effectively and to share results that are truly comparable and reproducible. As more researchers participate and collaborate, and as more results are aggregated into shared databases, significant new insights into the methods and materials of Chinese lacquer are sure to follow. Keywords: Chinese lacquer, Py-GC–MS, Laccol, Urushiol, Cedar oil Introduction and previously unreported materials were detected in Background lacquer in the JPGM collections. Our attention The collection of the J. Paul Getty Museum (JPGM) focused first on the surprising composition of seven- includes several pieces of French furniture dating to teenth-century Japanese export lacquers, and a the mid-eighteenth century that incorporate panels of summary of our results regarding these materials was Asian lacquer as part of their surface decoration. In first presented in 2009 (Heginbotham & Schilling, 2006, conservators at the JPGM and scientists at the 2011). Getty Conservation Institute (GCI) began a collabora- With the potential of the new analytical protocol tive project to study these objects and to develop an established in our minds, we next concentrated our improved analytical procedure that would allow the efforts on streamlining our procedures for data simultaneous analysis of the organic composition of interpretation and on expanding the range of materials Asian and European lacquer materials. By 2008 a pre- and formulations in our reference collection. In paral- liminary literature survey had been completed, a core lel with this work, we began to conduct analysis for set of reference materials had been assembled, and and with an increasingly large pool of collaborators an improved procedure using thermally assisted in museums and research institutions around the hydrolysis and methylation with tetramethyl- world. Through contributions from our collaborators ammonium hydroxide (TMAH) for pyrolysis-gas we produced a significantly expanded library of chemi- chromatography–mass spectrometry (THM-Py-GC– cal compounds, identifiable with THM-Py-GC–MS, MS) was presented (Heginbotham et al., 2008). It that are critical to identifying the raw materials soon became apparent that the new method was present in Asian lacquer samples. revealing an unexpected complexity in historic Asian Increasing interest in our research led to the devel- lacquer formulations, as a wide range of unexpected opment of a GCI workshop entitled ‘Recent Advances In Characterizing Asian Lacquers’ Correspondence to: Arlen Heginbotham, The J. Paul Getty Museum, 1200 (RAdICAL), through which we have shared our Getty Center Drive Suite 700, Los Angeles, CA 90049-1684, USA. Email: [email protected] sampling, staining, and data interpretation methods, © 2016 The J. Paul Getty Trust. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by- S3-28 nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Heginbotham et al. Some observations on the composition of Chinese lacquer as well as the library of marker compounds that we the methods and materials of Chinese lacquer are have compiled. Venues for RAdICAL workshops sure to follow. have included the Getty, Los Angeles, USA, (2012), the Institute for Preservation of Cultural Heritage at Anacards Yale, New Haven, USA, (2013) and the Center for It had long been assumed that Chinese lacquerware Research and Restoration of the Museums of has always been made from the urushiol-based France, Paris, France (2014). exudate of Toxicodendron verniciflua trees that grow throughout specific regions of China, Japan, and Korea. However, numerous analyses conducted at Chinese lacquer the Getty since 2007 have shown that many Chinese In the years since we began the method development lacquer objects produced for export in the early eight- phase of our research on Asian lacquer, we have had eenth century were formulated with laccol-based the good fortune to be able to study, sample, and lacquer, which is the exudate from Toxicodendron suc- analyze lacquer artifacts from across Asia and cedaneum. It is generally considered that these export Southeast Asia. In particular, we have studied a con- lacquerwares were produced in southern China. This siderable number of Chinese artifacts from as long corresponds well with the identification of laccol- ago as the second century BCE and have found many based lacquer in a group of eighteenth- and nine- compounds present in these samples that were, at teenth-century Cantonese objects in Portuguese first, mysterious to us. As was the case with our Royal Collections (Petisca et al., 2011). Although T. study of Japanese export lacquer materials, each dis- succedaneum is traditionally associated with covery of some group of new compounds in the Vietnamese and Taiwanese lacquers (Nimura & results from THM-Py-GC–MS would lead to further Miyakoshi, 2003), much Chinese export lacquer was research to try to understand their possible origins in produced in the south of China, near regions where the variety of raw materials that have found their this tree is widespread. Recent taxonomic research way into lacquer formulations across China and suggests that the range of so-called Vietnamese through the years. Often, an interpretation of the lacquer may extend further into southern China than chemical structure of the compounds would point to was previously known, with laccol trees identified in some possible classes of raw materials. Then, a Guangxi Province (Wan et al., 2007). search of the historical literature for recipes or other A substantial number of Chinese lacquer objects references materials would refine the possibilities. In made for the domestic Chinese market over the addition, inquiries directed to lacquer craftspersons course of the last 2000+ years have also been analyzed helped us to understand the function of different addi- at the Getty. As expected, most were found to have tives in lacquer formulations, while further searching been made using urushiol-based lacquer; however, of the scientific literature might connect our findings this was not always the case. One unusual example to research that had been conducted on these com- was a mid-sixteenth- century filled-in polychrome pounds or raw materials in allied fields. lacquer dish from the Victoria and Albert Museum, This paper is intended to summarize the various London, UK, (FE.87–1974), thought to have been information we have gathered over the years and the made in northern China and which depicts a five- trends we have observed with regard to the organic clawed dragon design and bears the mark of constituents of Chinese lacquer formulations. We are Emperor Jiajing (1521–66 CE). The ground (or foun- fully aware that this material is by no means compre- dation) layers were found to have been made with hensive or complete; it merely represents the state of laccol-based lacquer (with additions of cedar oil and our knowledge at the moment. Still, we hope that camphor), whereas a mixture of laccol and urushiol this information and the references compiled here was identified in the upper red layers. This may be will provide a useful foundation from which further explained by parallel archival research into contem- research may proceed. Considerable advances have porary Ming Dynasty records, which state that large been made in the last decade