Coating It

SCIENCE CHINA

Technological Sciences

RESEARCH PAPER July 2011 Vol.54 No.7: 1708 1714

doi: 10.1007/s11431-011-4439-4

The black pottery coating of longshan times from Taosi Site

LU XiaoKe1*, LI WeiDong1, LUO HongJie1, HE Nu2 & LI XinWei2

1

Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China;

2

Institute of Archaeology, Chinese Academy of Social Sciences, Beijing 100710, China

Received August 25, 2010; accepted March 17, 2011; published online May 15, 2011

Taosi is an archaeological site in Xiangfen county, Shanxi province. It is considered as a capital city site with the rudiment of

an early country in Longshan Times. In this work, the black pottery coating was found on the surface of black and grey pottery

of Longshan times and confirmed by scientific studies for the first time. It filled in the blank of pottery coating study in this

time period at the Yellow River Valley, as well as supplied a new study method of black skin pottery besides the carburiza-

tion craft. In addition, according to the archaeological materials, we inferred that the wares with this pottery coating might be

only used by the nobility at that time.

Taosi site, pottery coating, chemical composition, microstructure

Lu X K, Li W D, Luo H J, et al. The black pottery coating of longshan times from Taosi Site. Sci China Tech Sci, 2011, 54: 1708 1714,

Citation:

doi: 10.1007/s11431-011-4439-4

Black is a distinguishing feature of potteries in Longshan

1 Introduction

times and certain amounts of black potteries were found in

Taosi site. The carburization craft was recognized as the

Taosi site is located at the western foot of Taershan Hill,

reason why the pottery exhibited black in the former studies

about 7 kilometers northeast to the urban area of Xiangfen

[4 6]. However, researchers paid less attention to the pot-

county, Shanxi province. According to the radioactive 14C

tery coating issue. Pottery coating is a decoration craft on

age determination, the period of Taosi site is about from

the surface of ancient potteries, the earliest attempt of an-

2300 BC to 1900 BC. Taosi site has been confirmed as a

cients was using hand and water make the ware surface

large capital city site at the Yellow River Valley of Long-

smooth when the body became leather hard. When they

shan times by the archaeological excavation for many years

applied a mud layer to decorate the ware surface, it was the

[1], and the opinion that Taosi site is the Capital for King

pottery coating [7]. The pottery coating craft appeared in the

Yao in Ping yang was gradually becoming the focus in

early Neolithic Period and its function was not only to make

academic circles [2]. In recent years, excavators have suc-

the surface smooth but also for the artistic or religious faith

cessively found the walled-town of early and middle period,

when it was applied on the colored pottery of Yangshao and

the royal tombs, palace area, sacrifice area, storage area and

other cultures.

observatory and so on in Taosi site. These important dis-

In our work, the pottery shards from Taosi site were

coveries have fundamental significance to explore the

analyzed by component and structure analysis to reveal the

forming process of early China [3].

existence and scientific properties of pottery coating on the

black and grey pottery of Longshan times for the first time

and some significative results were obtained.

*Corresponding author (email: ********@****.***.**.**)

Science China Press and Springer-Verlag Berlin Heidelberg 2011 tech.scichina.com www.springerlink.com

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Lu X K, et al. Sci China Tech Sci July (2011) Vol.54 No.7

A piece of the pottery shard was cut off as an experi-

2 Experimental and results

mental sample first and then it was undergone a series of

preparation process including rubbing a section down, ul-

2.1 Energy dispersive X-ray fluoresce analysis (EDXRF)

trasonic cleaning and drying. The EDXRF results showed

The samples were all provided by the Shanxi Team of In- remarkable distinctions between the surface and inner body

stitute of Archaeology, Chinese Academy of Social Sci- of some samples labeled TS67, TS68, TS74, TS94, TS95,

ences and about 130 samples were selected from Taosi site. TS104 and TS105 with the vessel shapes of flat bottom ba-

The chemical composition of the surface and cross section sin, Dou, and three-legged cup. The appearance photo-

of each sample was determined by EDXRF (EDAX Ea- graphs of these samples are shown in Figure 1. According

gle-III Probe, USA). The EDXRF analyzer has advantages to macroscopic observation, it is hard to confirm whether

of non-destruction, high-precision and multielement analy- there is a pottery coating on the surface. The specific data

sis, is especially suitable for nondestructive analysis for the listed in Table 1 show that the chemical compositions on the

rare samples. surfaces of these samples are very similar and different

Figure 1 The appearances of the samples with pottery coating from Taosi site.

Table 1 The main chemical composition of the surface and cross section of some samples from Taosi site by EDXRF (wt%)

Code Time Name Area Test part Na2O MgO Al2O3 SiO2 K2O CaO TiO2 Fe2O3

surface 0.39 3.06 21.81 57.29 7.33 2.62 0.38 6.13

TS67 Later period basin abandoned palace

section 1.91 3.39 16.57 64.75 3.15 3.04 0.43 5.76

surface 1.13 3.38 19.61 59.59 5.22 3.51 0.42 6.12

TS68 Later period basin abandoned palace

section 2.04 3.25 16.38 64.87 3.24 3.13 0.40 5.68

surface 1.24 3.26 20.94 58.36 5.59 3.52 0.37 5.72

TS74 Later period Dou abandoned palace

section 1.62 3.19 16.11 64.68 2.94 4.73 0.43 5.31

surface 1.04 3.35 22.39 58.93 4.42 2.18 0.53 6.16

TS94 Later period Dou abandoned palace

section 1.80 3.22 17.05 65.30 3.17 2.02 0.48 5.95

surface 1.34 3.51 23.29 55.31 6.50 1.19 0.35 7.51

TS95 Later period Dou abandoned palace

section 0.40 2.99 16.82 65.41 3.27 3.98 0.41 5.73

surface 1.40 4.17 19.80 57.73 6.46 3.84 0.36 5.23

TS104 Later period cup abandoned palace

section 0.69 2.86 15.98 64.21 3.01 6.46 0.41 5.37

surface 0.60 3.58 22.81 59.38 4.28 1.87 0.43 6.05

TS105 Later period cup abandoned palace

section 0.63 2.58 15.27 66.87 2.83 5.37 0.40 5.06

1710 Lu X K, et al. Sci China Tech Sci July (2011) Vol.54 No.7

from those of the section bodies, the common characteris- There clearly exist pottery coatings on the surface of

tics of the difference are that the contents of Al2O3, K2O and TS67 and TS95 samples based on the microstructures re-

Fe2O3 on surface are higher than those in the cross section sults. The pottery coatings are very thin and the thickness

are about 10 20 m. There are basically no large particles

bodies. Therefore, it can be confirmed the existence of pot-

tery coatings on the samples. in the coatings, indicating that there were fine selection and

elutriation on the materials in ancient times. The coatings

with fine particle may fill the surface pit and make the sur-

2.2 Electron probe microanalysis (EPMA)

face compact and smooth. The EDS results of the pottery

The electron probe microanalysis has the double function of coatings section in Table 2 show that the contents of Al2O3,

microstructure and component analysis. After cutting, rub- K2O and Fe2O3 are all higher than those in the cross section

bing and burnishing of TS67 and TS95 samples, the micro- bodies, which was also confirmed by the EDXRF analysis.

structures were observed by EPMA (JXA-8100) and the The pottery coating also exists on the pottery jar from

results were shown in Figures 2 to 5. royal tombs of Taosi site and these samples are represented

Figure 2 Section microstructure of sample TS67 ( 100). Figure 4 Section microstructure of sample TS95 ( 100).

Figure 3 Section microstructure of sample TS67 ( 500). Figure 5 Section microstructure of sample TS95 ( 500).

Table 2 The chemical composition of pottery coatings and section bodies of TS67 and TS95 samples by EPMA (wt%)

Part MgO Al2O3 SiO2 K2O CaO Fe2O3

TS67 body 2.23 16.63 66.33 3.52 4.87 6.43

TS67 coating 2.25 22.70 55.39 8.55 1.70 8.38

TS95 body 2.78 18.83 57.74 4.24 3.42 7.69

TS95 coating 2.23 24.44 53.90 5.66 0.71 12.44

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by TS129 and TS131, their appearance photographs are and TS129 samples, and the XRD profiles are shown in

shown in Figures 6 and 7. Figure 10.

The Figure 10 shows the illite and -Fe2O3 phases in

The microstructure of the two samples in Figures 8 and 9

measured by EPMA show that the black skin on the sur- these pottery coatings, and there is also -Fe2O3 in TS95

face of TS129 is the pottery coating while the coating of coating beside -Fe2O3. As we know, -Fe2O3 is mainly

TS131 is under the white and red pigments. The thicknesses generated by magnetite in the oxidizing condition. There-

of the two coatings are about 10 m. The EDS results of the fore, the raw material of the pottery coating contains mag-

coatings in Table 3 show that their chemical composition is netite. In addition, the pure illite is fine and smooth, with

basically the same as the results in Table 2 except for the characteristics of white appearance and high contents of

low K2O content. Al2O3 and K2O. Based on the above analysis, the informa-

tion completely agrees with the characteristics of the

2.3 X-Ray diffraction analysis (XRD) black pottery coatings. Thus we can infer that this coating

is formed by the clays with main phases of illite and

The XRD (D/max 2550 V) analyzer was used to determine

magnetite.

the crystal components of pottery coatings of TS67, TS95

Figure 6 The appearance of sample TS129. Figure 8 The section microstructure of sample TS129.

Figure 7 The appearance of sample TS131. Figure 9 The section microstructure of sample TS131.

Table 3 The chemical composition of pottery coatings of TS129 and TS131 samples by EPMA (wt%)

MgO Al2O3 SiO2 K2O CaO Fe2O3

TS129 coating 2.34 25.98 56.55 3.69 2.77 8.68

TS131 coating 1.92 28.46 51.65 3.75 2.12 12.09

1712 Lu X K, et al. Sci China Tech Sci July (2011) Vol.54 No.7

nished. It indicates that the wares with the black pottery

coating were not commonly used at that time.

The pottery techniques of the colored decoration pottery

from the royal tomb in Taosi site were very complex. For

example, sample TS131 needed a lot of raw materials and

working procedures. This rightly means the corresponding

relationship between the grade of funerary wares and the

identity of grave masters. The black pottery coatings ap-

plied on the funerary pottery wares show that the exquisite

wares were always owned by the authority class and were

the symbol of distinguishing them from the civilians.

3.2 The source of raw materials of the black pottery

coating

The XRD results of the black pottery coating show that the

coating might be formed by the clays with main phases of

illite and magnetite. As we know, pottery coatings were

commonly used on the potteries in the Neolithic period.

Figure 10 The XRD profiles of pottery coatings of samples TS67, TS95

Before the Longshan times, the Yangshao culture was fa-

and TS129.

mous for its colored potteries. The former studies on the

white pottery coating and black/red pigments on the colored

3 Discussion

potteries showed that the white pottery coating was the clay

with high Al2O3 and the main color element of black/red

3.1 The function and particularity of the black pottery

pigments was Fe (some contain Mn) [8]. So the two raw

coating

materials (clay with high Al2O3 content and iron mineral) of

black pottery coating in Taosi site were already used for the

According to experimental results above, we confirm that

white pottery coating and black/red pigments in Yangshao

there are pottery coatings on some potteries from Taosi site.

culture. The coming out of this phenomenon should not be

Because this coating makes no change of the appearance

an accident and probably shows that the ancient Taosi pot-

color of the pottery ware and keeps it black and grey, which

ters mixed the two raw materials together purposefully to

is different from the colored pottery coating with marked

form a black coating on the pottery. Because black is the

and clear characteristics. The former studies only focused

epochal characteristic of Longshan culture, this phenome-

on the carburization craft and paid less attention of the pot-

non may also be the evidence of inheritance and develop-

tery coating research of black potteries. Compared with the

ment between different times. Though this black pottery

body materials, the pottery coating has high contents of

coating has high contents of K2O and Fe2O3 and the total

Al2O3, K2O and Fe2O3, which is formed by special materials.

flux contents exceed twenty percent, the pottery coating

The raw materials characteristic of this black pottery coat-

doesn t become glaze because of the relatively low firing

ing is different from the white coatings, or black/red pig-

temperature (about 1000 C) and the high Al2O3 content is

ments on the colored pottery in the former studies [8]. Be-

cause it was applied on the black pottery and didn t high- actually bad for the raw materials to form a glassy state. It

light decoration or beauty function. As we know, the col- should be noted that this black pottery coating doesn t high-

ored coating applied on the outside surface in Yangshao light decoration or beauty function but shows the practical

culture pottery was mainly for the beauty and religious faith usage, which is the obvious difference and progress com-

and the function of preventing seepage wasn t obvious. paring to the Yangshao colored pottery coating.

However, the black pottery coatings found in Taosi site

were mostly applied on the internal surface, so the purpose 3.3 The function analysis of TS95 sample and finger-

of preventing seepage was more obvious than the colored print on its surface

coating of Yangshao culture.

The above study has confirmed that there is pottery coating

In addition, there are other two special phenomena that

on the internal surface of TS95 sample. Judged from the

deserve more attention. One is the samples listed in Table 1

appearance photographs in Figure 11, its internal surface

were all unearthed from the abandoned palace area. The

and edge are very smooth. The internal surface is not com-

other is there are many samples with smooth and flat sur-

pletely black but partly red. There are some black spots on

face in the 130 selected samples and the pottery coating is

the outside surface, while a clear black fingerprint is near

only confirmed to exist in the samples listed in Table 1,

the edge.

only 5.4% of the total amount. Others might be only bur-

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Lu X K, et al. Sci China Tech Sci July (2011) Vol.54 No.7

Figure 11 The internal and outside appearance of TS95 and the detail of the fingerprint.

Although the internal surface is very smooth and bright, In addition, the vessel shape of TS95 sample is Dou and

the outside surface still preserves many rough wheel-turned the pottery Dou in ancient times was usually used as recep-

traces and the rare fingerprint of the potter four thousand tacle or lamp. The diameter of this pottery Dou is about 30

years ago. Concerning the particularity of the rare finger- cm. The internal surface of TS95 sample was also analyzed

print, we only use the non-destructive EDXRF analysis to by Fourier transformation infrared ray (FTIR), the result is

measure the chemical composition of the fingerprint and the shown in Figure 12.

results are shown in Table 4. The two strong absorption peaks at the wave number of

Table 4 shows that the chemical composition of the black

fingerprint on the outside surface is basically the same as

the pottery coating on the internal surface of TS95 sample,

indicating that the ancient potters got pottery coating mate-

rial on their fingers and impressed it on the outside surface

and reflecting the process of applying the pottery coating on

the surface from the side. In addition, that the fingerprint is

black indicates this pottery coating could become black

when it was fired in the kiln without carburization. Because

the carburization technique can t simply make the finger-

print black, that s the effect of pottery coating material itself.

Seen from the chemical composition data in Table 2, the

Fe2O3 content is 12.4% and the total flux content is 22%, so

we infer that the effect of high Fe2O3 content is the reason

why the fingerprint is black and bright. So there should be

variety techniques in making the pottery surface black in

Longshan times. Figure 12 The FTIR spectrum of the internal surface of TS95 sample.

Table 4 Main chemical composition of the fingerprint by EDXRF (wt%)

Na2O MgO Al2O3 SiO2 K2O CaO TiO2 Fe2O3

TS95 fingerprint 1.75 3.16 22.28 55.55 7.59 2.23 0.35 6.08

TS95 pottery coating 1.34 3.51 23.29 55.31 6.50 1.19 0.35 7.51

1714 Lu X K, et al. Sci China Tech Sci July (2011) Vol.54 No.7

2923 and 2854 cm 1 were caused by the stretching vibration (ii) So far the research has shown that pottery samples

with the black pottery coating were only unearthed from the

of methylene (CH2) of organic matters, so it can be con-

abandoned palace area and the noble grave of Taosi site,

firmed that some organic matters remain in the internal sur-

which indicate that these wares with pottery coating might

face of this sample. Although this pottery Dou has a big

be only used by the nobility.

disk and it was unearthed from the abandoned palace area of

(iii) The black and bright fingerprint on the outside sur-

Taosi site, it was still probably used as an oil lamp in the

face of TS95 sample indicates that this pottery coating ma-

palace at that time. According to the XRD results, there are

terials become black and bright by common firing in the

-Fe2O3 and -Fe2O3 in the internal surface, which is dif-

kiln without carburization technique, which may supply

ferent from the phase composition of other coatings with

another new study method of black skin pottery in the

only -Fe2O3. If this pottery Dou is a lamp, the high tem-

near future.

perature would make -Fe2O3 turn into -Fe2O3 when the

oil lamp was burning. Besides, the existence of -Fe2O3 can

also explain the reason why the part of the internal surface This work was supported by the Origin of Chinese Civilization Project

of National Key Technology R & D Program (Grant No. 2006BAK21B03).

is red. On the other hand, because the internal surface of

pottery Dou was soaked in oil in its long-term usage, still

some organic residue was detected in the surface after 1 He N, Yan Z B. The biggest townsite in Yellow River Valley has

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