THE TECHNOLOGY OF ‘GLAZED’ RESERVED SLIP WARE—A FINE CERAMIC OF THE HARAPPAN PERIOD*

Abstract

‘Glazed’ Reserved Slip Ware (RSW) is a high‐quality glossy bichrome pottery of the Indus Valley civilization, and dates to the mature Harappan period (c. 2600–1900 bc). Scanning electron microscopy with energy‐dispersive X‐ray analysis indicates that the surface coat on RSW is composed of a pale grey vitrified clay slip, which overlies a black slip with significantly higher iron oxide. Hence the term ‘sintered’ Reserved Slip Ware is to be preferred. X‐ray diffraction analysis indicates that both the pale and black slips contain hercynite, mullite and quartz, but observation by scanning electron microscopy shows that the black slips contain higher amounts of coarser‐grained hercynite. The elemental data suggest that different clays were used to make the bodies and the slips. However, key element ratios are very close in associated black and pale slips. The grey slip may have been produced by elutriation of the fine, iron oxide‐rich clay that was used to prepare the black slip. The pale grey slip was laid over the black and removed by combing to produce a bichrome effect, which evoked semi‐precious materials such as agate. RSW was a specialist product that required significantly higher input skill and resources than the majority of Harappan clay‐based ceramics. It is a further example of the range of sophisticated Harappan ceramic wares, which included faience, fired steatite and stoneware.