Tátrai Vilmos szerk.: A Szépművészeti Múzeum közleményei 95. (Budapest, 2001)

TÓTH, MÁRIA - BERTÓTI, IMRE - MOHAI, MIKLÓS - FÓRIZS, ISTVÁN -VOZIL, IRÉN: Material analysis of the bronze statuette of Imhotep

Besides the above mentioned crystalline phases, the presence of other phases below the detection limit of X-ray diffractometry cannot be excluded. Therefore, a highly sensitive test of chemical composition was also carried out. The results of the chemical analysis are summarised in Table 2. Table 2. Metallic components of the samples taken from the bronze statuette (on the basis of XPS and EDS studies) Sample Surface composition ( % by mass) Cu Sn Pb 1-1. 67 23 10 1-2. 66 23 11 1-3. 71 16 13 1-4. 73 27 trace 78 22 trace 1-5. 87 13 trace 78 20 trace On the basis of the results of the analyses, the samples can be categorised in two groups: lead containing alloy and lead free alloy. Samples taken from the chair and from its base belong to the lead free group, while samples from the footstool belong to the group containing lead. The distinction can be made by means of chemical analysis which complies with the image produced with powder diffractometry. Lead was found to be segregated in small clusters. Because of the small size of the sample, it was not possible to include portions rich enough in lead to be able to detect it by means of Xray diffraction. The results of the chemical analysis conducted again on further samples to verify the presence and/or absence of lead reasonably confirm the assumption that the materials had been processed differently. The alloy of the body and the footstool seems to be less inhomogeneous than the material of the chair and its base, although small variations can also be detected here. The EPMA studies of the samples taken from the clothing of the sitting figure included the generation of scanning electron micrograph image (fig. 29). EDS spectra are very good at confirming small fluctuations in the chemical composition which was mentioned above. It is possible to show that the proportions of Cu and Sn varies at distances of 50-100 Jim within a grain having a length of 300 p.m. There are also differences in the lead content (Diagrams 2 and 3). On the basis of the results of the chemical analysis two different materials, tin-lead-bronze (body, footstool) and tin-bronze (chair, base) can be identified. The parts of the statuette can also be distinguished on the basis of the sophistication of metallurgical processing, because the variation of Sn/Cu ratio is less significant in the chair and its base than in the body and footstool.