Limewashing paintings in Alentejo urban heritage: pigment characterization and differentiation by WDXRF and XRD |
| |
| Authors: | M Gil ML Carvalho A Seruya I Ribeiro I Queralt AE Candeias J Mirão |
| |
| Institution: | 1.Conservation and Restoration Dep., Science and Technology Faculty,Univ. Nova of Lisbon,Caparica,Portugal;2.Atomic Physics Center,,Lisbon University,Lisbon,Portugal;3.Portuguese Institute of Conservation Restoration (IPCR),Lisboa,Portugal;4.Laboratory of X-ray Analytical Applications,Institute of Earth Sciences “Jaume Almera” CSIC,Barcelona,Spain;5.Chemistry Dep. and évora Chemistry Center,University of évora,évora,Portugal;6.Giosciences Dep. and évora Geophysics Center,University of évora,évora,Portugal |
| |
| Abstract: | Pigments used in traditional limewashing paintings in Alentejo urban Heritage are inorganic materials and can be grouped into
four categories: a) reds – red ochre (from terras rossas, red schists and iron ore deposits weathering), almagres, terra roxa
(natural processed red ochres) and synthetic red iron oxides; b) yellows – yellow ochre (from schists and iron ore deposits),
processed natural ochres, yellow iron synthetic oxides, c) blacks – black earths and black iron synthetic oxides and d) blues
– artificial ultramarine. The present work proposes to characterize natural, natural processed and synthetic pigments by comparing
phase and elemental compositions. The results reveal differences in Fe, Si, K and Al total content according to their origin
and fabrication process and reveal intentional addition of white charges like carbonates. Elements like Zr, Ti, Cr, Mn, Ca
and Zn are present in all categories. Under optical microscopy, some samples of processed natural pigments do not exhibit
optical activity, thus revealing mixtures with synthetic pigments, while natural pigments present a strong birefringence colorless
due to optically active minerals.
PACS 78.70.En; 07.60.Pb; 61.10.Nz; 81.70.-q; 91.60.-x |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
