Micro-Raman spectroscopy analysis of 16th century Portuguese Ferreirim Masters oil paintings

In the present work a set of eight altarpieces of the 16th century (1532-1534), attributed to the Ferreirim Masters (Gregório Lopes, Garcia Fernandes and Cristóvão de Figueiredo), from the Santo António de Ferreirim Monastery (North of Portugal), were analysed by micro-Raman spectroscopy. For this purpose some samples were taken from the paintings to characterise its artist's 'school'. It was found that the preparation was made with chalk and gypsum and the palette composed mainly of lamp black, azurite, lead white (mixed with other pigments), lead-tin yellow type I, goethite (the main constituent of yellow ochre), red lead (as under painting), haematite (the main constituent of red ochre) and vermilion. Indigo was detected in one sample. Some derivatives and degradation products were found mainly in the panels subjected to high temperatures during a fire occurred in 1954: a degradation product from massicot or red lead, lead carbonate (dehydrated derivative of lead white), bassanite and anhydrite (hemi- and dehydrated forms of gypsum). These results are compared with those of previous total reflection X-ray fluorescence spectroscopy (TXRF) analyses.