The production technology of Iznik pottery—a reassessment*

Abstract

Previous research has established that Iznik pottery differs from other Islamic stonepaste pottery in that its stonepaste bodies contain lead oxide as well as soda and lime, and that a significant proportion of the tin oxide in its glaze is present in solution rather than as tin oxide particles. In order to better understand these distinguishing features, the chemical compositions and microstructures of Iznik pottery and tile samples, together with those of lumps of glass found in association, were investigated using both scanning electron and optical microscopy. These data have been supplemented by the study of replicate lead-alkali glazes produced in the laboratory with a range of different compositions. The results demonstrate that separate soda-lime and high-lead glasses were used in the production of Iznik stonepaste bodies, and that the total glass contents of the bodies were significantly higher than those quoted by Ab ¨ 'l-Q å sim, who was writing in about AD 1300. The very high purity of the lead-soda Iznik glazes indicated that the alkali flux used was either a purified plant ash or an as yet unidentified mineral source of soda. Replication experiments established that the high solubility of tin oxide in the glaze was due to the high purity of the glaze constituents. Furthermore, it is suggested that tin oxide was added to the glaze in order to give it a very slight opacity and thus obscure any blemishes in the underlying body.

The technological development of stonepaste ceramics from the Islamic Middle East

“…Second, no other Islamic glazes containing significant amounts of tin oxide with the majority in solution have been identified. As discussed by Paynter et al (2004), the high solubility of the tin oxide was due to the high purity of Iznik glazes (i.e., low potash, lime, magnesia and alumina contents) which, in turn, was probably the result of using a purified desert or coastal plant ash as the source of the alkali. Thus, as discussed by Tite (1989), there were no immediate antecedents to Iznik ceramics, and instead, the Iznik potters successfully adapted existing Islamic ceramic technologies in order to meet the demand of the Ottoman court for pottery that replicated the whiteness and resonancy of the coveted, imported Chinese porcelain.…”

Material Characterization of Ceramic Tile Mosaic From Two 17th-Century Islamic Monuments in Northern India

“…The bodies are of the quartz‐frit or stonepaste type (Tite 1989; Mason and Tite 1994; Mason et al . 2001; Paynter et al . 2004), but there are some variations in the structure and composition within samples from the same monument as well as between the two monuments.…”

“…Overall, the bodies are fundamentally stonepastes in the tradition of Islamic glazed pottery production—that is, consisting mostly of crushed quartz with minor amounts of clay or glass frit added as a binder—but are significantly coarser than those from medieval Islamic stonepaste, such as from Iznik (Paynter et al . 2004) or Syria and Iran (Mason et al .…”

“…2001). Despite this difference in grain size, there seems to be no major difference in bulk composition (Paynter et al . 2004).…”

An assessment study of tiles from Topkapı Palace Museum with energy‐dispersive X‐ray and Raman spectrometers

“…In recent years, a limited number of research was conducted on Ottoman ceramics recovered from ‘Iznik Kiln’, ‘Istanbul Tekfur Palace’, and ‘Kütahya’ excavations and also a few shards and objects from the museum collections to obtain information on the technology employed in their production . Researchers used an optical light microscope and scanning electron microscopy‐energy dispersive X‐ray spectroscopy (SEM‐EDS) techniques for those studies.…”