A technological study of ancient faience from Egypt

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Abstract

The chemical compositions and microstructures of some 35 faience objects from Egypt spanning the period from the Middle Kingdom through to the 22nd dynasty are determined using analytical scanning electron microscopy. Replicate faience beads glazed in the laboratory using the efflorescence and cementation methods are similarly investigated. In efflorescence glazing, there appears to be preferential efflorescence of soda over potash, and in cementation glazing, preferential take up of potash over soda into the glaze. These data are then used to try to infer the raw materials and methods of glazing employed in the production of the ancient faience. The glaze/glass phases present in the faience differ significantly in composition from that of New Kingdom glass. This could be due either to the use of different plant ashes or to changes in the composition of the plant ashes during the production of faience and/or glass. Although it is only rarely possible to determine with certainty whether ancient faience was glazed by efflorescence, cementation or application, the observed microstructures provide an indication of the approach adopted to achieve desired performance characteristics such as strength.

Introduction

Faience, which consists of a ground quartz or quartz sand body coated with a soda-rich glaze, was first produced in both Egypt and the Near East as early as the 4th millennium BC, and continued in production through until the Roman period. The material was used to produce bowls and tiles as well as small objects such as amulets, beads, rings and scarabs. Initially the principal colorants were copper and manganese producing turquoise and black glazes, respectively. Then, with the beginning of glass production around 1500 BC, the glaze colours were extended to include cobalt blue, manganese purple and lead antimonate yellow.

The most comprehensive survey of the production technology of ancient Egyptian faience has been provided by Kaczmarczyk and Hedges (1983) with an appendix by Vandiver (1983). Kaczmarczyk and Hedges presented semi-quantitative analyses of a large number of faience glazes spanning the period from Predynastic through to the 1st century AD, the main emphasis being on the identification of the colorants used. Vandiver extended the study with visual and low-power optical microscopic examination of the faience objects in an attempt to determine, on the basis of macroscopic evidence, whether the faience was glazed by the efflorescence, cementation or application method. Tite et al. (1983) and Tite and Bimson (1986) extended the investigation of the methods used to glaze faience through the examination of the microstructures of both ancient and laboratory replicate faience using scanning electron microscopy (SEM). On the basis of these results, they proposed microstructural criteria for distinguishing between the different methods of glazing. Tite and Shortland (2003) included faience in an investigation of the production technology of the overall range of copper- and cobalt-blue vitreous materials from the New Kingdom site of Amarna. On the basis of the microstructures and the chemical compositions of the glazes and the glass phases present in the faience bodies, as determined using an analytical SEM, they attempted to infer both the raw materials and methods of glazing used in the production of the faience.

However, published quantitative compositional data for Egyptian faience still remains somewhat limited. Therefore, a primary aim of the present study is to significantly extend the available compositional and microstructural data for Egyptian faience, an analytical SEM again providing the principal method of examination. Faience bowls, finger rings and beads from Abydos, Amarna and Esna spanning the period from the Middle Kingdom through to the 22nd dynasty have been examined. In order to assist in the interpretation of the data for the ancient faience, replicate beads glazed in the laboratory by both the efflorescence and cementation methods have been similarly examined. For both groups of material, the compositional profiles through the glaze into the body of the samples have been investigated. From these data, an attempt is made to determine for the ancient faience the nature of the raw materials, and in particular the plant ashes providing the alkali flux used in producing the glaze, as well as the methods of glazing.

Section snippets

Samples

The faience objects studied included bowls, finger rings and beads, the majority of which were blue-green in colour. The nine Abydos bowls were glazed on both their inner and outer surfaces which in most cases were decorated with black painted designs (Fig. 1a, b). Related to the bowls in terms of context are the hippopotamus and an egg-shaped object which were similarly glazed over their outer surfaces. This group of material, together with the Abydos finger ring (Fig. 1c), all come from

Results

In describing the faience microstructures, as observed in the SEM (Fig. 2, Fig. 5, Fig. 6, Fig. 7), it is convenient to distinguish between (1) the essentially quartz-free glaze layer (GLZ), (2) the interaction layer (IAL) between the glaze and body which consists of quartz embedded in a more-or-less continuous matrix of glass, and (3) the body itself which can contain varying amounts of interparticle glass (IPG) that bonds together the quartz particles. (NB Following the recommendation of

Efflorescence glazing

The composition profiles for the replicate efflorescence glazes indicate that there was preferential efflorescence of sodium carbonate as compared to potassium, calcium and magnesium carbonates and copper oxide. The differential efflorescence of sodium and potassium carbonates is perhaps surprising since the solubility of potassium carbonate is significantly greater than that of sodium carbonate (i.e. 100 g/cm3 compared to 7 g/cm3). One possible explanation is that, because of its lower

Conclusions

The composition profiles for the replicate efflorescence and cementation faience have provided new data on the differential efflorescence and differential take up into the glaze, respectively, of the components of the glazing mixtures used. Thus, there appears to be preferential efflorescence of sodium carbonate over potassium carbonate, probably as a result of the significantly lower solubility of the former. Conversely, in cementation glazing, there appears to be preferential take up into the

Acknowledgements

We are extremely grateful to Professor Elizabeth Slater, Dr Steven Snape and Miss Patricia Winker for helping us to select and date, and for allowing us to take samples from, the faience objects held in the School of Archaeology, Classics and Egyptology Museum at the University of Liverpool. We are also indebted to Professor Ian Freestone for valuable discussions, particularly with respect to the processes occurring in efflorescence and cementation glazing. Peter Bray and Neil Young are thanked

References (16)

  • A.J. Shortland et al.

    Natron as a flux in the early vitreous materials industry: sources, beginnings and reasons for decline

    Journal of Archaeological Science

    (2006)
  • R.H. Brill

    Chemical Analyses of Early Glasses: Volume 1 (tables) and Volume 2 (catalogue)

    Corning Museum of Glass

    (1999)
  • Hatton, G.D., 2005. The technology of Egyptian Blue. Unpublished DPhil thesis, University of...
  • A. Kaczmarczyk

    The source of cobalt in ancient Egyptian pigments

  • A. Kaczmarczyk et al.

    Ancient Egyptian Faience

    (1983)
  • Paynter, S., 2001. The development of vitreous materials in the Ancient Near East and Egypt. Unpublished DPhil thesis,...
  • E.V. Sayre et al.

    Analytical studies of ancient Egyptian glass

  • Shortland, A.J., 2000. Vitreous materials at Amarna. B.A.R. International Series 287,...
There are more references available in the full text version of this article.

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    In the Near East, particularly in Iran, faience is still being produced using traditional techniques (Matin and Matin, 2012). Faience generally consists of a sand or finely ground quartz core coated with a colored alkaline-lime-silicate glaze (Matin and Matin, 2012; Rehren, 2008; Tite et al., 2007, 1983; Tite and Shortland, 2008; Toffolo et al., 2013). Three different glazing methods can be employed in the production of faience objects – application glazing, efflorescence glazing or cementation glazing (or Qom technique) (Matin and Matin, 2012; Tite et al., 1983; Toffolo et al., 2013).

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