![]() The compositional dissimilarities of the studied enamels suggest that each colour was independently fritted. The results of this study are only broadly consistent with the archival documented 18 th century technologies. The pure (99.5 Au, 0.5 Fe 2O 3) gilt consists of several folded gold particles. Violet is a mechanical blend of flower’s blue and purple. 0.5 μm) in a glassy matrix (47 PbO, 46 SiO 2, 5 K 2O). Purple is very homogeneous and shows tiny drops of pure gold (max. ![]() The opaque red overglaze enamel is a mechanical mix of yellow Pb–Sb oxide crystals with an iron-rich (16 Fe 2O 3) Pb–silica glass. Opaque olive green colours are created by the combination of such yellow crystals with a bluish, Cu and Co bearing glassy matrix. Pseudohexagonal shaped platelets of Pb–Sb–Sn triple oxide crystals, embedded in a colourless glassy matrix, generate the opacity and the colour of the yellow paints. Two blue colours, for the dentil comb and the flower painting, are chemically distinct (colouring CoO in the dental rim 7, in the flower’s blue 2 mass%) and contain many As- and Pb-rich globules and dendrites. The maximum thickness of the different paints is 50 μm, with 15 μm as mean thickness of the individual paint stroke. The 50–90 μm thick, transparent lead glaze (40.9 PbO) contains 47.6 SiO 2, 6.5 K 2O and 3.5 CaO and shows a 35–75 μm thick reaction zone (50 SiO 2, 30 PbO, 14 CaO) towards the body. The body is rich in SiO 2 (73 mass%), CaO (16) and alkali oxide (8) and shows acicular wollastonite and tridymite crystals embedded in a glassy matrix consisting of SiO 2 (75), K 2O (12) and CaO (9). ![]() Optical microscopy, X-ray diffraction, X-ray fluorescence and scanning electron microscopy analyses were carried out on a typical Sèvres soft (frit) porcelain plate from 1781 in order to determine the chemical and mineralogical composition as well as the microstructure of its ceramic body, glaze, overglaze decoration and gilding. ![]()
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