Raman spectroscopy applied to early (ca. 1746–1754) English steatitic porcelains: a tentative study of compositions

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In 2008, excavations were conducted by the Northern Ceramic Society at the site of the former Lancaster delftware potworks, which operated between 1754 and about 1790. The recovered sherds have been non-destructively examined by Raman and electron microscopies and the iron phases in the biscuit by Mössbauer spectroscopy. These methods have provided a new understanding of the mineralogy of the delftware produced at Lancaster using clay imported from Carrickfergus in Ireland and blended with the local ferruginous-aluminous clays. This has implications for the attribution of delftware produced at Liverpool, Bristol, Scotland and Ireland. The Carrickfergus clay has been found to be highly dolomitic resulting in the body of the delftware forming diopside and the magnesian olivine forsterite, when fired. Brookite had not converted to rutile, nor had tridymite, nor cristobalite formed; the K-feldspars did not undergo further chemical reactions, and the observation of metakaolin would suggest that the biscuit firing temperature was in the order of 800-900°C. Chalcedony containing moganite was established as the silica source. A cobalt-containing lead-tin glaze was applied to the biscuit body and, after decorating, was fired. The mineralogy of the pigments used to decorate the objects indicate the yellow to be the PbSbSn triple oxide, the green to be a copper silicate mixed with lead-tin yellow, the purple and browns to be manganese silicates and the blue to contain cobalt spinels and cobalt pyroxenes. Diopside crystals together with recrystallised tin agglomerates have been observed floating within the glaze.

Section: Pigmentssupporting

confidence: 76%

Section: Redmentioning

confidence: 99%

Lancaster delftware: a Raman spectroscopy, electron microscopy and Mössbauer spectroscopy compositional study

Jay

Cashion

Blenkinship³

2015

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“…Jay and Orwa used Raman spectroscopy applied to early (ca. 1746–1754) English steatitic porcelains as a tentative study of compositions . Joseph et al .…”

Section: Art and Archeologymentioning

confidence: 99%

Recent advances in linear and nonlinear Raman spectroscopy. Part VII

Nafie

2013

“…The terminology such as ‘hard‐paste’ and ‘soft‐paste’ as used to describe English and European porcelain suffers from earlier and often inappropriate descriptions provided by many collectors and writers. With respect to English porcelain, the present descriptive terminology has been previously discussed in some detail by Jay and Orwa and by Godden…”

Section: Resultsmentioning

confidence: 99%

Raman spectroscopy of Limehouse porcelain sherds supported by Mössbauer spectroscopy and scanning electron microscopy

Jay

Cashion

2013

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The Limehouse pot works, founded probably in the early 1745, was one of the earliest porcelain works established in England. It closed in June 1748. The factory site at 20 Fore Street Limehouse, London, was excavated by the Museum of London, Department of Greater London Archaeology in 1990, recovering 1402 sherds. A number of these sherds has now been examined by Raman spectroscopy, scanning electron microscopy and one by Mössbauer spectroscopy. Different porcellaneous formulations have been identified; namely, an experimental Si-Al body with a Si-Al-Ca glaze and a Si-Al-Ca body containing minor Pb and Mg and covered with a Si-Pb-Ca glaze. Several sherds were intermediate between these compositions. Most sherds failed to reach vitrification temperature and lack translucency. Mössbauer spectroscopy indicated that one sherd had been fired under mildly reducing conditions. These results have enabled conclusions to be reached in respect of the raw materials, body and glaze compositions and firing and glazing conditions used at Limehouse.