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Limewashing paintings in Alentejo urban heritage: pigment characterization and differentiation by WDXRF and XRD


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.

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  1. J. Aguiar, Cor e a cidade histórica: estudos cromáticos e conservação do património, 2nd edn. (Faup publicações, Porto, 2005)

  2. P. Scarzella, P. Natale, Terre coloranti naturali e tinte murali a base di terre (Stamperia Artistica Nazionale, Torino, 1989)

    Google Scholar 

  3. M. Elias, C. Chartier, G. Prévot , H. Garay , C. Vignaud, Mater. Sci. Eng. B 127, 70 (2006)

    Article  Google Scholar 

  4. M. Gil, M.L. Carvalho, A. Seruya, A.E. Candeias, J. Mirão, I. Queralt, Yellow and red ochre pigments from southern Portugal: Elemental composition and characterization by WDXRF and XRF (to be published)

  5. R.M. Cornell, U. Schwertmann, The Iron Oxides: Structure, Properties, Reactions, Occurences and Uses, 2nd edn. (Wiley-VCH GmbH & Co.KGaA, Weinheim, 2003)

  6. D. Hradil, T. Gryga, J. Hradilová, P. Bezdicka, Appl. Clay Sci. 22, 223 (2003)

    Article  Google Scholar 

  7. J.A.C. das Neves, Relatório sobre a Exposição Universal de Londres de 1862, Estudos geologicos de mineraes uteis e as suas applicações (Imprensa Nacional, Lisboa, 1862)

  8. M.S. Pinto, A.S. Andrade, Comunicações dos serviços geológicos de Portugal 84, 38 (1998)

    Google Scholar 

  9. C. Genestar, C. Pons, Anal. Bioanal. Chem. 382, 269 (2005)

    Article  Google Scholar 

  10. N. Eastaugh, V. Walsh, T. Chaplin, R. Siddall, Pigment Compendium: Optical Microscopy of Historical Pigments (Elsevier Butterworth-Heinemann, London, 2004)

    Google Scholar 

  11. H. Howard, Pigments of English Medieval Wall Paintings (Archetype publications, London, 2003)

    Google Scholar 

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Correspondence to M. Gil.

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78.70.En; 07.60.Pb; 61.10.Nz; 81.70.-q; 91.60.-x

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Gil, M., Carvalho, M., Seruya, A. et al. Limewashing paintings in Alentejo urban heritage: pigment characterization and differentiation by WDXRF and XRD. Appl. Phys. A 90, 49–54 (2008).

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