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Study of degradation processes of blue and yellow pigments

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Natasha Fioretto Aguero
Total Authors: 1
Document type: Master's Dissertation
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Instituto de Física (IF/SBI)
Defense date:
Examining board members:
Marcia de Almeida Rizzutto; Marcia de Mathias Rizzo; Fabio Rodrigues
Advisor: Marcia de Almeida Rizzutto

In archeometry and applied sciences, physical and chemical methodologies are very useful for studying different materials and objects of cultural heritage such as easel paintings, murals, ceramics, metals, etc. In the particular case of paintings, such analyses can help in understanding the creative process, the materials used by the artist and the conservation status of this work. In the context of this latter item, signs of degradation, such as color change, can be characterized. In order to understand the degradation of some pigments by light exposure, the cadmium yellow (CdS), chrome yellow (PbCrO4), cobalt blue (CoAl2O4) and cerulean blue (Co2SnO4) pigments were studied, the latter two being also mixed with zinc white pigment (ZnO). Such studies were carried out through three experiments prepared with these pigments: photodegradation induced in the TGM (Toroidal Grating Monochromator) line of the National Laboratory of Synchrotron Light; exposure to ultraviolet light in the SOL-UV solar simulator; and exposure to ultraviolet, visible and infrared radiation in a chamber designed in this master\'s degree. The results pointed out changes in all samples, especially in their reflectance spectrum in the visible region. Finally, samples obtained from works by the painter Candido Portinari that had signs of chromatic alteration were analyzed. Based on these fragments, stratigraphic models of the materials used by the artist in these paintings could be constructed. (AU)

FAPESP's process: 14/26151-8 - Study of the degradation processes of blue and yellow pigments
Grantee:Natasha Fioretto Aguero
Support Opportunities: Scholarships in Brazil - Master