- University of Granada researchers have used this technique to analyse the paintings in the Palacio de la Madraza in Granada, Spain, built during the Nasrid Dynasty’s
New scientific advances made at the University of Granada in the field of Heritage Science have allowed the characterization of various historical pictorial material, the study of alteration processes and the identification of interactions between paint components. The researchers used new applications based on multivariate techniques to analyze the spectral data obtained from different analytical techniques.
Additionally, University of Granada researchers have used for the first time a new method including the chemical characterization and quantification of microtextures (size and number of grains at each crystalline phase) to date a set of polychrome paintings according to the pictorial technique and materials employed.
Using this method of analysis, the researchers determined the nature of, manufacturing and pigment alteration processes in pictorial layers. Moreover, the scientists identified the historical interventions conducted on the Palacio de la Madraza Yusufiyya (built in 1349 AD during the reign of Yusuf I (Nasrid Dynasty)). This monument is of great historical significance, both for its cultural and religious role in the Nasrid period -among the most important in Al-Andalus-, and for its political role -it became the seat of the City Council in 1500 nd the seat of the decisions of the Knights XXIV, by order of the Catholic Monarchs.
This research study was conducted by Julia Romero Pastor at the University of Granada Department of Mineralogy and Petrology, and coordinated by professors Carolina Cardell Fernández and Alejandro Rodríguez-Navarro a the Department of Analytical Chemistry. This study represents a significant step forward in the field of Heritage Science and, particularly, in the scientific analysis of paintings.
Chemometric and Analystical Techniques
The studies were conducted on painting copies made with the traditional egg tempera technique. Firstly, spectral data were obtained from infrared spectroscopy (ie T-FTIR, DRIFTS and ATR-FTIR), Raman spectroscopy and mass spectrometry (MALDI-TOF MS). Then, the data obtained were processed for Principal Component Analysis (PCA), which yielded clue information.
The study revealed that the interaction between certain components of pigment binding and pigment-protein assembly result in the formation of metal complexes. In addition, researchers identified some changes in the secondary structure of the protein, and found that certain mineral pigments have a protective effect that provides stability to the tempera against UV radiation.
Also, the combined use of a range of analytical techniques such as Micro-X-ray diffraction, Raman microscopy, scanning electron microscopy and gas chromatography allowed the University of Granada scientists to conduct a thorough and comprehensive analysis of the stratigraphy of the paint layers in the Palacio de la Madraza. In particular, through this analysis, researchers identified the original Nasri paint layers, thus bringing light to the understanding of the pigments and painting techniques used during the Nasri period. Furthermore, scientists have identified the interventions that the Monument has suffered over the centuries.
Few studies are available on the interactions between paint components, and on their role in the conservation of paintings. Hence the importance of this study, which is based on a multidisciplinary work involving different departments of the University of Granada, such as that of Mineralogy and Petrology, or that of Analytical Chemistry and Painting.
The results of this study have been partially published in articles included in Journal Citation Reports such as Analytical Chemistry, Journal of Raman Spectroscopy, Vibrational Spectroscopy, Journal of Mass Spectrometry and Analytica Chimica Acta.
Pictures attached:
Detail of the polychrome fresco in the oratory of the Palacio la Madraza.
b)Stratigraphy of the paint layers under the petrographic microscope, and c) 2D Diffraction pattern of the sample obtained through X-ray microdiffractio
Contact: Julia Romero Pastor. the University of Granada Department of Mineralogy and Petrology. Phone number:+34 958 24 66 14. E-mail address: juliaromero@ugr.es
