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GEOREF RECORD

Red lead darkening in wall paintings; natural ageing of experimental wall paintings versus artificial ageing tests

Sebastien Aze, Jean-Marc Vallet, Monique Pomey, Alain Baronnet and Olivier Grauby
Red lead darkening in wall paintings; natural ageing of experimental wall paintings versus artificial ageing tests
European Journal of Mineralogy (December 2007) 19 (6): 883-890

Abstract

The mechanisms of red lead pigment darkening were investigated through complementary observations and analyses of naturally aged experimental wall paintings. Red lead transformation into mainly plattnerite [beta -PbO (sub 2) ] and also anglesite [PbSO (sub 4) ] was established by mineralogical analyses of a micro-sample using focused X-ray diffraction and confirmed by micro-Raman spectroscopy. According to both optical and electron microscopy observations, beta -PbO (sub 2) appears to have formed in the outer part of the paint surface, while PbSO (sub 4) is only located in a thin superficial layer. Structural features of plattnerite crystals were investigated using both scanning and transmission electron microscopy. Besides, red lead stability in various conditions was assessed by means of a set of physico-chemical tests applied on both raw pigment and experimental paintings. The pigment alteration is assumed to occur through the sulfation into anglesite of lead monoxide initially present in the pigment, followed by the so-called "solvolytic disproportionation" of Pb (sub 3) O (sub 4) . Such an alteration process is controlled by environmental parameters, namely humidity, temperature and sulfate concentration, which depend on the oxidative dissolution of atmospheric SO (sub 2) pollutant.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 19
Serial Issue: 6
Title: Red lead darkening in wall paintings; natural ageing of experimental wall paintings versus artificial ageing tests
Affiliation: Centre Interregional de Conservation et Restauration du Patrimoine, Marseille, France
Pages: 883-890
Published: 200712
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 48
Accession Number: 2008-028874
Categories: General geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Secondary Affiliation: Centre de Recherche sur la Matiere Condensee et les Nanomateriaux, FRA, France
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200809
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