Analytical investigation of Mudéjar polychrome on the carpentry in the Casa de Pilatos palace in Seville using non-destructive XRF and complementary techniques.

The pigments, execution technique and repainting used on the polychrome wood ceilings and doors in the Casa de Pilatos (Seville, Spain) were studied using portable X-ray fluorescence equipment. Cross-sections of small samples were also analysed by optical microscopy, SEM with EDX analysis, micro-Raman and micro-infrared spectroscopy and X-ray diffraction. These carpentry works are magnificent examples of the Mudéjar art made in Spain in the early 16th century. Portable X-ray fluorescence gave good information on the different components of the polychrome. The SEM-EDX study of the surfaces of small samples gave information on their components and also characterized the compounds that had been deposited or formed by environmental contamination or by the alteration of some pigments. The SEM-EDX study of cross-sections facilitated the characterization of all layers and pigments from the support to the most external layer. The following pigments were characterized: red (cinnabar/vermillion, lead oxide, iron oxides and orpiment/realgar), black (carbon black), white (white lead and titanium barium white), yellow-orange-red-brown (orpiment/realgar and iron oxides), green (chromium oxide), blue (indigo blue and ultramarine blue), and gilding (gold leaf on bole). False gold, bronze and brass were also found. The pigments were applied with the oil painting technique over a support layer that had been primed with animal glue. This support layer was gypsum in some cases and white lead in others. This study is essential to the polychrome conservation of the studied artwork, and it will help clarify uncertainties in the history and painting of Mudéjar art.

XRF, µ-XRD and µ-spectroscopic techniques for revealing the composition and structure of paint layers on polychrome sculptures after multiple restorations.

This paper presents the novel application of recently developed analytical techniques to the study of paint layers on sculptures that have been restored/repainted several times across centuries. Analyses were performed using portable XRF, µ-XRD and µ-Raman instruments. Other techniques, such as optical microscopy, SEM-EDX and µ-FTIR, were also used. Pigments and other materials including vermilion, minium, red lac, ivory black, lead white, barium white, zinc white (zincite), titanium white (rutile and anatase), lithopone, gold and brass were detected. Pigments from both ancient and modern times were found due to the different restorations/repaintings carried out. µ-Raman was very useful to characterise some pigments that were difficult to determine by µ-XRD. In some cases, pigments identification was only possible by combining results from the different analytical techniques used in this work. This work is the first article devoted to the study of sculpture cross-section samples using laboratory-made µ-XRD systems.

Murillo's paintings revealed by spectroscopic techniques and dedicated laboratory-made micro X-ray diffraction.

This paper describes one of the first case studies using micro-diffraction laboratory-made systems to analyse painting cross-sections. Pigments, such as lead white, vermilion, red ochre, red lac, lapis lazuli, smalt, lead tin yellow type I, massicot, ivory black, lamp black and malachite, were detected in cross-sections prepared from six Bartolomé Esteban Murillo paintings by micro-Raman and micro-XRD combined with complementary techniques (optical microscopy, SEM-EDS, and FT-IR). The use of micro-XRD was necessary due to the poor results obtained with conventional XRD. In some cases, pigment identification was only possible by combining results from the different analytical techniques utilised in this study.

Advanced combined application of micro-X-ray diffraction/micro-X-ray fluorescence with conventional techniques for the identification of pictorial materials from Baroque Andalusia paintings.

The process of investigating paintings includes the identification of materials to solve technical and historical art questions, to aid in the deduction of the original appearance, and in the establishment of the chemical and physical conditions for adequate restoration and conservation. In particular, we have focused on the identification of several samples taken from six famous canvases painted by Pedro Atanasio Bocanegra, who created a very special collection depicting the life of San Ignacio, which is located in the church of San Justo y Pastor of Granada, Spain. The characterization of the inorganic and organic compounds of the textiles, preparation layers, and pictorial layers have been carried out using an XRD diffractometer, SEM observations, EDX spectrometry, FT-IR spectrometry (both in reflection and transmission mode), pyrolysis/gas chromatography/mass spectrometry and synchrotron-based micro-X-ray techniques. In this work, the advantages over conventional X-ray diffraction of using combined synchrotron-based micro-X-ray diffraction and micro-X-ray fluorescence in the identification of multi-layer paintings is demonstrated.

Characterization of illuminated manuscripts by laboratory-made portable XRD and micro-XRD systems.

Illuminated Arabic manuscripts have been studied, employing two laboratory-made X-ray diffraction (XRD) systems developed recently in the C2RMF laboratory. The validity of the micro-XRD and XRD portable systems for the study of this type of artworks has been demonstrated. A common observation in all the analyses is the presence of calcite and rutile; also, hematite, goethite, cinnabar, brass, anatase and barite were detected in the various colours. Differences between the results obtained by both techniques due to acquisition mode are discussed. In addition, other techniques such as X-ray fluorescence (XRF) and micro-Raman were used for the complete characterization of the manuscripts.

Study of the gilding technique used in polychromed stones and ceramics by dedicated laboratory-made micro X-ray diffraction and complementary techniques.

This work describes the use of a new dedicated laboratory-made micro X-ray diffraction system for detecting the phases present in cross-sections of artworks. As an example, the phases present in samples from gilding ceramics and stone sculptures from the heritage of Seville (Spain) were successfully detected using this new system, which takes advantage of various devices developed for synchrotron radiation, and is complemented by the information provided by other techniques.

Non-destructive analysis of cultural heritage artefacts from Andalusia, Spain, by X-ray diffraction with Göbel mirrors.

The characterization of the phases present in artefacts has been normally carried out using XRD (Bragg-Brentano geometry) that requires sampling from artworks, being a destructive technique. However, X-ray diffraction with Göbel mirrors permits directly to study rough artefacts without sampling. Grazing incidence attachments can be used to characterize as much the superficial layer as the underlying ones in flat samples to obtain information about the depth profile of some samples. The combination of Göbel mirrors and measure at low fixed incidence angles allow to obtain information about the depth profile of bent samples. This work reports the alteration processes on the surface of the following cultural heritage artefacts: a rivet and a nail extracted from Pardon Gateway, located in the North façade of Mosque-Cathedral of Cordoba; a Roman arrow and a button from a Roman jacket obtained from an excavation in Baena (Cordoba); organ pipe from Cathedral of Zaragoza; lead seals from Seville City Hall collection. The main objective of this paper is the study through a totally non-destructive analytical method, X-ray diffraction with Göbel mirrors, of the superficial alteration of some metallic artefacts from cultural heritage. This knowledge allows us the election of appropriate methods to carry out the restoration of these artefacts.

The effect of sonication on dioctahedral and trioctahedral micas.

This paper reports on the effect of sonication on two mica samples. The materials have been investigated in terms of structure modifications, particle size and morphology, specific surface area and thermogravimetric behaviour. The effect of the mica structure, namely density and distribution of cations over the octahedral sites, on the sonicated products is reported. Sonication produces delamination and reduction of lateral size of the original macroscopic materials yielding nanometric flakes that retain the structure of the material, unlike other procedures previously reported in literature, such as dry grinding, that produces severe structural damage.

The effect of ultrasound on the particle size and structural disorder of a well-ordered kaolinite.

The present study examined the effect of sonication on the particle size and structure of a well-crystallized (KGa-1) kaolinite from Georgia. Sonication produced an important delamination effect as well as a reduction of the other particle-size dimensions. The experiments, carried out under different experimental conditions, showed that particle-size reduction can be controlled through different variables such as power of ultrasonic processor, amount of sample (kaolinite + water), and time of treatment. As a consequence of this particle-size reduction the surface area increases sharply with the sonication time from 8.5 to 83 m2/g after 20 h with the most energetic treatment. Contrary to what is observed in the grinding treatment, sonication did not cause the amorphization of kaolinite, as observed by XRD and FTIR data. Nevertheless, ultrasound treatment increased the structural disorder, which consisted in increases in the proportion of specific translations (-a/3+b/3) between adjacent layers in the first hours of treatment, followed by increases in the proportion of random translations between layers.