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Research ArticleReceived: 1 January 2009 Accepted: 2 April 2009 Published online in Wiley Interscience: 10 July 2009

(www.interscience.wiley.com) DOI 10.1002/jrs.2340

Pigment identification and decoration analysisof a 5th century Chinese lacquer paintingscreen: a micro-Raman and FTIR studyTao Li,a∗ Yun-Feng Xie,a Yi-Min Yang,a Chang-Sui Wang,a Xiao-Yang Fang,a

Ji-Long Shib and Qiu-Ju Hec

To investigate the pigments and decoration applied to a wood-based lacquer painting screen from the tomb of Si-maJin-long, Shanxi Province, central China, made by Chinese craftsmen in the 5th century, a combination of micro-Ramanspectroscopy, Fourier transform infrared spectroscopy (FTIR), wavelength dispersive X-ray fluorescence (WDXRF), andmicroscopic examination was used. The obtained results are as follows: (1) the black, yellow, and red colors are identified ascarbon black, orpiment and realgar, and cinnabar, respectively, by using micro-Raman spectroscopy. The FTIR result showsthat the white pigment filled in the leaves is not lead white, as assumed in the literature, but gypsum. Whether lead white wasused at other locations remains unanswered and requires more samples for further work; (2) the thickness of each discernablepigment layer, as observed under the microscope, is approximately equal and the differences among them are small, suggestinga superfine painting skill; besides, a noticeable smooth interface between wood and the red grounding substance indicatesthat a polishing process might have been applied before the painting; (3) the red background was proved to contain cinnabar,but further FTIR analyses found no evidence for the presence of Chinese wood oil; and (4) the most interesting finding, rarelyreported before, is that white grains of different sizes are found in both pigment layers and the grounding substance, which areperhaps an intentional addition. Further, in situ XRF and Raman analyses indicate that they are sourced from hydroxyapatite,coming probably from the intentional addition of animal bone ash to the lacquer. But how such a process could be finished andwhat purpose it served have not yet been answered. Copyright c© 2009 John Wiley & Sons, Ltd.

Keywords: Northern Wei; Tomb of Si-ma Jin-long; lacquer painting screen; micro-Raman spectroscopy; FTIR spectroscopy

Introduction

Worldwide, China is probably the country that made the earliestuse of lacquer. The oldest lacquerware known heretofore is a7000-year-old bowl coated with a cinnabar-containing lacquerfilm, which was unearthed from the Neolithic He-mu-du remainsin Yu-yao, Zhejiang Province, southeastern China, in 1979.[1,2]

Based on archeological excavations,[3 – 11] the locations of earlyuse of lacquerware in China (between the Neolithic age andHan Dynasty) are shown in Fig. 1, in which the sites where thelacquerware manufactured or used have been excavated areshown.

The Northern Wei (386–534 A.D.) tomb of Si-ma Jin-long was firstdiscovered in 1965 accidentally by Chinese construction workers.It is located in central China, close to the Shi-jia-zhai village, Da-tong, Shanxi Province. The tomb bears dated inscriptions of 474and 484 A.D., and the epitaphs identify the owners as a NorthernWei official in a high position named Si-ma Jin-long and hisnomadic wife named Ji-chen. Although it had been robbed, thetomb has still more than 400 excavated artifacts. Both organic andinorganic materials, such as painted potteries, porcelains, carvedstones, beads, artifacts made of bronze and iron, and also of wood,bamboo and bone, have been found.

The most remarkable finding from the tomb of Si-ma Jin-longwas lacquer fragments with figure painting, which illustrated aConfucian moralizing text both in style and content and obviouslyfollowed the Han Chinese art tradition. The five largest fragmentsare roughly of similar size and relatively well preserved. Each piece

measures about 80 cm long, 20 cm wide, and 2.5 cm thick.[12] Onesuch fragment, as shown in Fig. 2, has a red background, on whichfinely drawn black lines delineate the forms. All the faces andhands are painted in white. The figures are accompanied by someinscriptions, written in black ink on a yellow background.

Since its excavation, the screen has been in the focus of attention.To historians of Chinese art, the lacquer painting screen fragmentsare of great significance because

• they had a distinctive Chinese character, both in style andcontent;

• the style is very similar to some sections of the ‘admonitions’scroll by the famous figure painter Kai-zhi Gu (mid-4th to 5thcentury);

• the clear dated inscriptions were rare among their contempo-raries;

∗ Correspondence to: Tao Li, Department of Scientific History and Archaeometry,Graduate University of the Chinese Academy of Sciences, Yuquan Rd. 19 (A),Beijing 100049, China. E-mail: tao-li@live.com

a Department of Scientific History and Archaeometry, Graduate University of theChinese Academy of Sciences, Beijing 100049, China

b Center of Printing History Research, Beijing Institute of Graphics andCommunication, Beijing 102600, China

c Division of Preservation and Conservation, Capital museum, Beijing 100045,China

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Figure 1. The distribution of lacquerware based on excavations in China:black circles stand for those manufactured or used before the Qin Dynasty(5000–206 B.C.); empty stars are for those manufactured or used duringthe Han Dynasty (206 B.C.–220 A.D.). This figure is available in colour onlineat www.interscience.wiley.com/journal/jrs.

• the handwriting on the tomb, which is believed to signify theofficial script, bears an ancient style of calligraphy defined andprevalently used in the Han Dynasty (202 B.C.–220 A.D., severalhundred years before the origin of the screen).[13]

The discovery of the tomb of Si-ma Jin-long, in particular theChinese-style painted screen fragments, has revealed importantnew information on the art and culture of Northern Wei, aboutwhich very little is known. The screen is classified as NationalFirst-Class Cultural Relics of the People’s Republic of China, and isrestricted to exhibitions abroad.[14]

The present work aims to identify and determine the fourmajor colors (red, black, yellow, and white), and also to uncoverthe decoration applied on the screen, with the combineduse of micro-Raman spectroscopy, Fourier transform infrared(FTIR), wavelength dispersive X-ray fluorescence (WDXRF), andmicroscopic examination.

Experimental

Samples

Several fragments of different sizes were generously offered foranalysis by the Da-tong museum, which houses the unearthedartifacts from the tomb of Si-ma Jin-long. All fragments are fromunknown sources (original locations). In the present work, the fourlargest fragments are analyzed. For convenience, we designatethem as A, B, C, and D.

First, we carefully observed all samples. From the differencesin colors and painting contexts, we deduced that the samplescame from different parts of the screen. The decorative patternson sample B are too vague to discern, due to severe degradation,whereas patterns on other samples are visible and beautiful.Detailed information is given in Fig. 3 and Table 1.

Figure 2. One relatively well-preserved fragment of the screen (afterbeing repaired and restored). This figure is available in colour onlineat www.interscience.wiley.com/journal/jrs.

Table 1. Description of all samples

Sample Description

A The surface is covered in a wide range by a white, opaquefilm, which is loose and brittle; underneath the film,flower petals are discernable, and three colors can berecognized: red, black, and yellow; red is used as abackground, on which black lines are drawn and yellowis filled.

B No patterns can be recognized; two colors arediscernable: red and yellow; yellow, with loose grains, ispainted on the red background.

C Same as sample A.

D Flower petals are clear and distinguishable; four colors arediscernable: red, black, yellow, and white; patterns withblack outlines are filled with yellow and white, on thered background.

Methods

Microscopic observation

In this work, the cross-sectional observation is made by thefollowing steps: (1) embedding the samples. Epoxy resin wasused to embed samples. Then the embedded samples were leftto harden at room temperature; (2) polishing. A metallographicgrinder was first used for roughly polishing the embedded test

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Figure 3. Photos of sample A to D (a–d). This figure is available in colour online at www.interscience.wiley.com/journal/jrs.

samples, and then sandpaper was used till a smooth surface wasproduced; and (3) observation under a microscope.

A VHX-600 digital microscope (Keyence, Japan), which enablesnondestructive, high-resolution image acquisition with numerousimage processing capabilities, was used in the reflected lightmode for cross-sectional observation and also for photographingthe samples.

Micro-Raman analysis

Micro-Raman spectroscopy analysis was performed by means of aJobin Yvon Raman system (JY-T64000 Raman system). A 785-nmnear-infrared (NIR) diode laser was used as the excitation source.The size of the light spot was 1 µm, and the laser power used at thesample was 2 to 15 mW. The spectral resolution was ∼0.2 cm−1. A50× objective lens was used for positioning.

FTIR analysis

FTIR measurements were carried out with an Avatar 360spectrometer (Nicolet, USA) in the 4000–400 cm−1 spectral range.Absorption spectra were obtained from pellets of sample grainsmixed and milled with KBr.

WDXRF analysis

WDXRF measurements were carried out at an XGT-5000 (Horiba,Japan) system coupled with an Rh X-ray tube as source. Theexcitation conditions were as follows: potential, 50 kV; current1 mA; X-ray beam diameter 100 µm; and the collection time forspectrum 300 s.

Results and DiscussionPigment identification

By a comparison of the Raman and FTIR spectra with thosepublished in some related work, the four major colors on the screen

Table 2. The analyzed colors and pigments identified in the presentwork

Sample Color Classification Chemical formula

A Black Carbon black C

B Yellow Orpiment; Realgar As2S3; As4S4

C Red Cinnabar HgS

D White Gypsum CaSO4 · 2H2O

were successfully identified. The analyzed colors, the identifiedpigments, and the Raman and FTIR spectra are shown in Table 2and Figs 4–7, respectively.

Raman analysis of the black

Raman spectra of the black on sample A and C can be easilyidentified as carbon black, because the broad Raman bandsat 1350–1380 and 1580–1600 cm−1, as shown in Fig. 4, arecharacteristic of amorphous carbon.[15,16]

Carbon black is the substance that could easily be foundand used as a colorant. It is usually produced by incompletecombustion of organic matter, such as plants, oil, bones, etc.,and has been used as black pigment since the Paleolithicage. In China, an early use of carbon black as pigment isin a ground painting found in 1982 at the Neolithic Da-di-wan remains (3000 B.C.), in Gansu Province, northwesternChina.[17]

In the present work, a Raman band at 960 cm−1, which isbelieved to be a feature of phosphate, is absent. This indicatesthat the use of bone black, the black residue chiefly of tribasiccalcium phosphate and carbon from bones, can be ruledout.[18]

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Figure 4. Raman spectra of the black from (a) sample A and (b) sampleC. Recording conditions for (a) 50×, 2 mW, 30 s × 2; for (b) 50×,3 mW, 20 s × 2. This figure is available in colour online atwww.interscience.wiley.com/journal/jrs.

Figure 5. Raman spectra of the yellow from (a) sample B, (b) sample D, and(c) sample D. Recording conditions for (a) 50×, 3 mW, 15 s × 2; for (b) 50×,15 mW, 3 s × 2; and for (c) 50×, 3 mW, 5 s × 2. This figure is available incolour online at www.interscience.wiley.com/journal/jrs.

Raman analysis of the yellow

Figure 5 shows Raman spectra of the yellow on sample B and D,which contains peaks at 383, 353, 334, 310, 293, 235, 226, 216, 202,177, 154, 145, and 136 cm−1.

The peaks at 383, 353, 310, 293, 226, 202, 177, 154, and136 cm−1 are identified as belonging to orpiment (As2S3), acommon monoclinic arsenic sulfide mineral with an orange toyellow color,[19,20] whereas the rest (334, 235, 226 and 145 cm−1)to realgar (As4S4), an arsenic sulfide mineral with an orange-redcolor.[21,22] Literature from mineralogy and geology shows thatthese two minerals are frequently found in association with eachother in nature.

In China, the history of orpiment and realgar used as pigments isquite long. Ma and Berke[23] have shown that as early as 3700 yearsago, orpiment and realgar were used as pigments at the Huo-shao-

Figure 6. Raman spectra of the red from (a) sample A, (b) sample C, and(c) sample D. Recording conditions for (a) 50×, 3 mW, 30 s × 2; for (b) 50×,3 mW, 5 s × 2; and for (c) 50×, 3 mW, 10 s × 2. This figure is available incolour online at www.interscience.wiley.com/journal/jrs.

Figure 7. FTIR spectra of the white pigment from different loca-tions of sample D. This figure is available in colour online atwww.interscience.wiley.com/journal/jrs.

gou site, Yu-men, Gansu Province; besides, further evidence showsclearly that from that time on, they have been constantly chosenas the pigment to paint yellow.[24 – 26]

The period of use of orpiment and realgar in Chinese lacquer-ware for decoration purpose, as evidenced from archeologicalexcavations, might be no later than the Spring and Autumn andWarring States periods (770–221 B.C.).[27]

Raman analysis of the red

The spectra of the red color on samples A, C, and D provide verystrong signatures of cinnabar (HgS), a mercury(II) sulfide mineralwith a bright red color, with peaks at 344, 284, and 251 cm−1, asshown in Fig. 6.

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Figure 8. Pigments layers observed under the microscope in the cross section of (a) sample A; (b) sample B; (c) sample C; and (d) sample D. This figure isavailable in colour online at www.interscience.wiley.com/journal/jrs.

Figure 9. (a) Photos of sample C; (b) locations from where the samples for FTIR analysis were collected; and (c) FTIR spectra of the two samples. This figureis available in colour online at www.interscience.wiley.com/journal/jrs.

Cinnabar is among the few pigments that were used by ancientChinese people from a very early time. Its strong ability to maintainbright colors for thousands of years makes it the best choice as ared pigment. The earliest use of cinnabar on Chinese lacquerwareto date is in the 7000-year-old cinnabar-containing lacqueredbowl, as mentioned in the introduction.[28]

FTIR analysis of the white

Since the noise from fluorescent background of the white onsample D was too strong for micro-Raman analysis, an FTIR analysiswas conducted. Good FTIR spectra were obtained with some smallwhitish particles picked up from the sample. The peaks at 3548,

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Figure 10. Whitish particles of different grain sizes found in both pigment layer and the transition region in sample C. This figure is available in colouronline at www.interscience.wiley.com/journal/jrs.

Table 3. Thickness of each discernable pigment layer observed ineach sample

Thickness of pigment layers (µm)Number of

Sample observable layers Red Yellow White Black

A 3 Fig. 8(a) 39.3 33.8 – –

B 4 Fig. 8(b) 42.9 35.1 – 43.0

C 2 Fig. 8(c) 29.3 – – –

D 3 Fig. 8(d) 35.1 – 42.9 –

3408, 1681, 1618, 1414, 1125, 669, 599, and 459 cm−1, as shown inFig. 7, were identified to be those of gypsum (CaSO4 · 2H2O),[29] acommon white or colorless mineral.

Clear evidence at the Huo-shao-gou site, Yu-men, GansuProvince, shows that gypsum was already used as a pigmentas early as 3700 years ago.[30] Besides its use as a pigment, gypsumwas used also as a construction material as early as 5000 years ago,as some recent work has pointed out.[31]

In the excavation bulletin of the tomb of Si-ma Jin-long,published in the Chinese archeological journal Wen Wu (CulturalRelics) in 1973, the excavators visually inspected the white powderpainted on the faces and hands of figures and believed that itwas lead white (PbCO3),[32] a poisonous white amorphous powderwidely used as pigment in ancient Chinese art. Since then, manyreports, books, and articles have quoted this assumption.

But in the present work, the FTIR result shows that the whitepigment from sample D (filled in the flower petals) is not leadwhite but gypsum. Whether lead white was also used at otherlocations requires further studies.

Decoration analysis

Cross-sectional observation

Under the microscope, the cross section of each sample showstwo or more distinguishable layers, as shown in Fig. 8. By using themicroscope along with the measurement software, the thicknessof each discernable pigment layer was recorded, and the averagevalue measured at more than 30 different locations is given inTable 3.

In Fig. 8, we can easily see that each pigment layer is filled withfinely ground grains and has also a uniform thickness; and betweenthe wood and the red background there is always a transitionregion which shows obvious differences in both color and density.The interface between the wood and the red background seems

smooth and even, as observed in all samples, indicating that somepolishing treatment may have been applied before the lacquering.

FTIR analysis of the red background

Since the Han Dynasty, Chinese wood oil, a drying plant oilconsisting of mainly eleostearic acid (C17H29· COOH), has beenuniversally used and added to the lacquer to make surface oflacquerware more smooth, bright, and stable.[33] To determinewhether or not Chinese wood oil was used in the manufacture ofthe screen, samples from the red background were collected forFTIR analysis from sample C. Details on the sampling and the FTIRresults are shown in Fig. 9.

In Fig. 9, the main features seen in the two FTIR spectra are almostthe same. Peaks at 3405, 2927, 2852, 1620, 1453, and 1091 cm−1

are identified as belonging to the Chinese lacquer.[34] Since thered pigment contained in the background has been identifiedas cinnabar, we may safely conclude that cinnabar and Chineselacquer were mixed before painting on the wooden surface.

In 1992, a research report by Zheng et al.[35] was published, inwhich FTIR spectra of lacquer mixed both with and without Chinesewood oil were studied and carefully compared. As pointed outin the report, the peak at 1710 cm−1 usually showed a higherintensity than the peak at 1620 cm−1 in the FTIR spectra of lacquermixed with Chinese wood oil, whereas the situation with FTIRspectra of the lacquer mixed without Chinese wood oil was justthe opposite, which was supposed to be seen as an indicator ofwhether or not Chinese wood oil was added to the pigment.

But, as can be seen clearly from Fig. 9(c), peaks observed at1710 cm−1 are too vague to be even discerned, compared to verystrong peaks at 1620 cm−1. Based on such an observation, we areinclined to conclude that Chinese wood oil may not have been beadded to the lacquer during the painting process.

The finding of whitish particles of different grain sizes

When the cross sections were observed under the microscope, avery interesting finding was noticed that, in both the pigment layerand the transition region, scattered whitish particles of differentgrain sizes were present, as can be seen in Fig. 10.

In Fig. 10(a), superfine ground whitish particles can be noticedin the cinnabar-containing layer (the red background). Since thethickness of the layer is less than 50 µm, the largest grain diameteris estimated to be less than 20 µm; while in the transition region, asshown in Fig. 10(b), the situation is very different: whitish particlesare found normally of a measured thickness of near or larger than100 µm.

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Figure 11. µ-XRF spectrum of the analyzed whitish particle. This figure isavailable in colour online at www.interscience.wiley.com/journal/jrs.

Figure 12. Raman spectrum of the analyzed whitish particle. This figure isavailable in colour online at www.interscience.wiley.com/journal/jrs.

To determine the whitish particles’ elemental composition andalso their mineral phases, we performed µ-XRF and Micro-Ramananalyses on a whitish particle with a grain diameter of ∼100 µm.The analysis results are shown in Figs 11 and 12.

The µ-XRF result, as shown in Fig. 11, reveals clearly thatthe analyzed grain has high concentrations of calcium andphosphorous, whereas Fig. 12 shows a strong Raman band at∼970 cm−1, assigned to the ν(PO) symmetric stretching of thephosphate ion.[36]

Based on the obtained results, and also with reference toand a careful consideration of Sun’s[37] literature review onthe lacquering techniques developed and used during the HanDynasty, in which the blending of lacquer and animal bone ashwas described, along with Jin’s[38] spectroscopic analyses andthe finding of hydroxyapatite (Ca5(PO4)3OH) on ancient lacquerfilms, we deduce that the whitish grains observed in the presentwork probably have their origin from hydroxyapatite, the maininorganic component of bones, from the intentional addition ofanimal bone ash to the lacquer.

But, sadly, the reasons why hydroyapatite was added, as wasquestioned in Jin’s[38] work, and why hydroyapatite of differentgrain sizes were added to different regions, as noticed in this work,still remain unanswered.

Conclusions

Four fragments coming from a 5th century Chinese lacquerpainting screen, with different painted colors, were investigatedwith the combined use of micro-Raman, FTIR, µ-XRF, andmicroscopic examination.

Our analyses show the following.

• The pigments identified are carbon black, orpiment and realgar,cinnabar, and gypsum, which were used to color black, yellow,red, and white, respectively. Further work is needed to confirmwhether lead white was used at other locations.

• The thickness of each discernable pigment layer, as observedunder the microscope, is approximately equal and thedifferences among them are small, suggesting a superfinepainting skill; besides, a noticeable smooth interface betweenthe wood and the background indicates a possible polishingprocess before the painting.

• The red background was proved to contain cinnabar, butfurther FTIR analyses found no evidence for the existence ofChinese wood oil.

• The white grains found both in the pigment layers and in thegrounding substance were of different sizes, and is thought tobe an intentional addition probably sourced from bone ash.But how such a process could be finished and what purpose itserved have not yet been answered.

Acknowledgements

This work would not have been possible without the cooper-ation of the Datong Museum, Shanxi Province, China. Besides,the authors also acknowledge the financial support from theKnowledge Innovation Project of the Chinese Academy of Sci-ences (No.KJCX3.SYW.N12), Research Foundation for TalentedScholars from Graduate University of the Chinese Academy ofSciences, and the Beijing Municipal Commission of Education(No.KM200810015007).

References

[1] The He-mu-du Archaeological Team, Cult. Relic. 1980, (05), 5.[2] J. Z. Cao, J. Chin. Lacquer 1990, 9(4), 30.[3] S. L. Chen, J. Chinese Lacquer 1983, 2(2), 4.[4] S. E. Liu, J. Chin. Lacquer 1985, 4(3), 24.[5] F. W. Shen, The History of the Traditional Chinese Lacquer Art, The

People’s Fine Arts Publishing House: Beijing, 1991.[6] Z. Y. Zhu, Lacquer Wares, Shanghai Ancient Books Pressing House:

Shanghai, 1995, pp 1.[7] Q. X. Yang, Jianghan Archaeol. 1995, 21(2), 56.[8] S. L. Wang, J. Z. Cao, J. Chin. Lacquer 2002, (02), 16.[9] W. M. Ji, Chengdu Wen Wu 2005, (3), 43.

[10] R. Zhang, Ancient Lacquer Wares, Cultural Relics Press: Beijing, 2005.[11] S. Hong, Research of Lacquer Wares in the Warring States, Qin and

Han dynasties, Cultural Relics Press: Beijing, 2006.[12] Datong Museum of Shanxi province, Relics Working Committee of

Shanxi province, Cult. Relic. 1972, (3), 20.[13] L. Lucy, The Northern Wei Tomb of Ssu-ma Chin-lung and Early Chinese

Figure Painting, UMI Research Press: Ann Arbor, MI, 1990.

J. Raman Spectrosc. 2009, 40, 1911–1918 Copyright c© 2009 John Wiley & Sons, Ltd. www.interscience.wiley.com/journal/jrs

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18

T. Li et al.

[14] Z. S. Ma, Illustrated Dictionary for Classification of Chinese CulturalRelics (A1 Quality), Shanghai Lexicographic Publishing House:Shanghai, 1992, p 386.

[15] H. G. M. Edwards, E. M. Newton, J. Russ, J.Mol.Struct. 2000, 550–551,249.

[16] D. C. Smith, A. Barbet, J. Raman Spectrosc. 1999, 30, 321.[17] J. F. Yu, L. H. An, Cult. Relic. Central Chin. 1992, (2), 72.[18] G. D. Smith, R. J. H. Clark, J. Archaeol. Sci. 2004, 31, 1146.[19] I. M. Bell, R. J. H. Clark, P. J. Gibbs, Spectrochim. Acta, Part A 1997, 53,

2176.[20] B. Wehling, P. Vandenabeele, L. Moens, R. Klockenkamper, A. van

Bohlen, G. van Hooydonk, M. de Reu, Mikrochim. Acta 1999, 130,256.

[21] A. R. David, H. G. M. Edwards, D. W. Farwell, D. L. A. De Faria,Archaeometry 2001, 43(4), 470.

[22] L. Burgio, R. J. H. Clark, Spectrochim. Acta, Part A 2001, 57, 1493.[23] Q. L. Ma, H. Berke, Sci. Conserv. Archaeol. 2006, 18(1), 4.[24] X. A. Li, J. Shanxi, Teach. Univ. (Soc. Sci. Ed.) 2002, 29(3), 12.[25] J. Y. Wang, Sci. Conserv. Archaeol. 2003, 15(3), 47.[26] Q. L. Ma, B. M. Su, Z. D. Hu, Z. X. Li, Appraisal, Analysis, and Scientific

Conservation of Chinese Heritage, Science Press: Beijing, 2001,pp 203.

[27] K. H. Zhao, J. N. Zhou, History of Science and Technology of China(Volume of Chemistry), Science Press: Beijing, 1998, pp 342.

[28] J. Z. Cao, J. Chin. Lacquer 1990, 9(4), 31.[29] W. S. Peng, G. K. Liu, Infra-red Spectra Atlas of Minerals, Science Press:

Beijing, 1982, p 235.[30] Q. L. Ma, B. M. Su, Z. D. Hu, Z. X. Li, Appraisal, Analysis, and Scientific

Conservation of Chinese Heritage, Science Press: Beijing, 2001, p 203.[31] N. S. Li, N. He, Z. W. Mao, J. Instrument. Anal. 2005, 24(5), 9.[32] Datong Museum of Shanxi province, Relics Working Committee of

Shanxi province, Cult. Relic. 1972, (3), 25.[33] J. B. Zheng, W. F. Shan, W. Zhang, S. Q. Guo, J. Fudan Univ. (Nat. Sci.)

1992, 31(3), 343.[34] K. L. Hu, Y. D. Li, J. L. Yang, C. G. Fan, C. S. Wang, Spectrosc. Spectr.

Anal. 1994, 14(5), 32.[35] J. B. Zheng, W. F. Shan, W. Zhang, S. Q. Guo, J. Fudan Univ. (Nat. Sci.)

1992, 31(3), 347.[36] H. G. M. Edwards, D. W. Farwell, Spectrochim. Acta, Part A 1995, 51,

2077.[37] J. Sun, Cult. Relic. 2004, (12), 50.[38] P. J. Jin, Sci. Conserv. Archaeol. 2007, 19(3), 48.

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