Multi-analytical identification of pigments and pigment mixtures used in 17th century Portuguese azulejos

Autores: Coentro, S.|Momoso, J.M.|Lima, A.M.|Silva, A.S.|Pais, A.N.

Fuente: J. Eur. Ceram. Soc.doi:10.1016/j.jeurceramsoc.2011.07.021
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multi-analytical approach was used to study the pictorial layers of a set of 17th century historic glazed tiles (azulejos) of Portuguese manufacture. The pictorial layer was studied by µ-EDXRF, µ-Raman, SEM-EDS and OM. Although the established palette comprises few pigments, it was found that the tiles were enhanced by the use of pigment mixtures, which were identified by µ-Raman and µ-EDXRF. As expected, the blue colour derives from cobalt oxide, purple from manganese oxide and emerald-green from copper oxide. Regarding the yellow pigment, µ-Raman results show it is consistent with the composition of a ternary oxide, whereas µ-EDXRF shows a high intensity of Zn in this colour, indicating a composition close to a Pb?Sb?Zn ternary oxide. Some compounds from the original ores were also indentified: in two very dark blue samples, cobalt and nickel olivines (a-Co2SiO4, a-Ni2SiO4), and in a dark brown sample, braunite (a manganese silicate).