The main goal of this research was to design and characterize the capabilities of a portable confocal μXRF system that allows the noninvasive in situ analysis of easel paintings in combination with other spectroscopic and multispectral techniques, more specifically, XRF, IRR and UV-induced visible fluorescence. We shall see the great potentiality and ability of the imaging and spectroscopic methodology, totally non-invasive, and for the first time the results on the chiaroscuro woodcuts produced in Northern Europe between the 16th and 17th century. Finally, the study of watermarks by transmitted light provides information about the origin of the paper support. On the other hand, fiber optics reflectance spectroscopy (FORS) in infrared and visible ranges, X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy allow the detection of presence of paper treatments and the characterization of pigments and in some cases dyes. Together with false color infrared photography (IRFC), they allow a first evaluation of the pigments and dyes used in the inks and the study of their sequence of application. On one hand, imaging techniques provide microscopic and macroscopic observations of the color prints. The methodology, entirely non-invasive and non-destructive, consists in the complementary use of imaging and spectroscopic techniques. The aim of this work is to analyze the ink and paper chemical composition, and to define the sequence of printed layers in order to understand how the artists and their workshop achieved visual effects. This ar chaeometric study of color prints from chiaroscuro woodcuts is of particular interest for those artworks still unfamiliar with this type of approach. The "CLARO" project deals with the analysis of the inks (pigments and colorants) and the watermarks of color prints carried out in Germany, France and the Netherlands between 15. Con ello, se pretende mejorar la estrategia de análisis mediante otras técnicas puntuales. A la luz de esos primeros resultados, se propone una metodología para la evaluación preliminar de los pigmentos empleados en obras pictóricas antiguas. Para el estudio de las pruebas se emplearon cuatros dispositivos registrando una parte especifica del espectro infrarrojo. Los objetivos son de establecer la opacidad y transparencia características de cada material, considerar la influencia de la superposición de capas de distintos materiales y evaluar el comportamiento de distintos equipos. Ese trabajo propone analizar estándares de referencia realizados con pigmentos típicos del siglo XVI. Aunque poco explorado, este registro contiene también información que ayuda a la identificación de los pigmentos presentes en la superficie de la obra. Esa técnica revela la presencia de dibujos preparatorios. La reflectografía infrarroja (IRR) se ha vuelto un método de registro de imagen clásico para el estudio de obras pictóricas. In this paper, we'll evaluate the efficiency of the softwares for images assemble and we'll discuss the characteristics, advantages and options in the use of two capture systems for IRR. For the mosaics assemble, the software considered were VARIM (Visión Artificial aplicada a la Reflectografía de Infrarrojos Mecanizada, version 1.0.7), Kolor Autopano Giga (Version 2.4.6) and Microsoft ICE (Microsoft Image Composite Editor, version 1.4.4.0). We have analyzed sixteenth century paintings of large format using two Xenics cameras with InGaAs detector. This international collaboration proposes a comparison between two methods of image capture and three different software for the assemble of multiple images. In other hand, for complete infrared images of large format easel paintings, it is necessary to control the lighting, in order to ensure the same conditions of each reflectogram captured. Consequently, it is important to find a way to obtain a complete picture of the entire artwork in order to be able to perform contrast's observation. Depending on the size of the artwork, the result can be tens to thousands of images that have to be integrated into an assemble. As it's well known, reflectograms measured with InGaAs detector camera are relative small images and the camera must be placed at a close distance from the painting. It also provides information useful to decriminalize several pigments on the artwork's surface based on the change contrast's observation of the IRR image. This technique reveals the presence of preparatory drawings, testimonies of painter's skills and the organization of his workshop. Van Asperen de Boer thesis (1968), infrared reflectography (IRR) has become a classic image registration method for paintings studies.
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