Fiber optic reflectance spectroscopy in the 270-1700 nm range was used to identify white pigments typically used in 20th-century paintings and as restoration materials, such as lead white, zinc white, titanium white in the two crystalline forms anatase and rutile, lithopone, and kaolin. Use of the non-invasive,in situ technique was undertaken in accordance with the principles of minimum intervention, which guide the restoration and conservation of artworks. With this technique, a suitable spectroscopic database of the pigments was first created, using various instrumental set-ups. Subsequently, fiber optic reflectance spectroscopy was applied to the study of two paintings from the Galleria di arte moderna, Palazzo Pitti, Florence: Mercato by Elisabeth Chaplin, dating probably from the 1920s, and Renaioli, painted in 1950 by Bruno Rosai. The purpose was to better understand the evolution of the use of such white pigments during the past century, and also to provide useful information concerning questions of chronology.TITRE-La spectroscopie de reflectance par fibre optique comme technique non invasive pour 1'identification de pigments blancs dans les peintures du 20e siec1e RESUME---'-On a utilise la spectroscopie de reflectance par fibre 6ptique (FORS), dans la region de 270-1700 nm, pour identifier les pigments blancs generalement employes en peinture et en restauration au 20e siecle. Parmi ces pigments, on retrouve Ie blanc de plomb, Ie blanc de zinc, Ie blanc de titane dans ces deux formes cristallines (1' anatase et la rutile), Ie lithopone et Ie kaolin. L'utilisation de FORS, une technique non invasive et realisee in situ, respecte Ie principe d'intervention minimale qui guide la pratique de la conservation et de la restauration des cruvres d'art. Grace a cette technique, on a d' abord cree une base de donnees spectroscopiques des pigments en utilisant divers reglages instrumentaux. Ensuite, on a applique FORS a l' etude de deux peintures de la Galleria di arte moderna, au Pallazzo Pitti a Florence: Mercato par Elisabeth Chaplin, datee probablement des annees 20, et Renaioli par Bruno Rosai, peint en 1950. Le but de cette etude etait de permettre une meilleure comprehension de l' evolution de l'emploi de pigments blancs au cours du dernier siecle et de fournir des informations utiles quant a leur chronologie.TITULO-Identificacion no invasiva de pigmentos blancos en pinturas al oleo del siglo XX por medio de espectroscopia de reflectancia con fibras opticas RESUMEN-Se usa la espectroscopia de reflectancia con fibras opticas (FORS del ingles fiber optic reflectance spectroscopy), en el rango espectral de 270-1700 nm, para identificar pigmentos blancos usados dpicamente en pinturas del siglo XX y como materiales de restauracion, tales como blanco de plomo, blanco de zinc, blanco de titanio, en sus dos formas cristalinas rutilo y anatasa,litopon y caolinita. El uso in situ de la tecnica no invasivaFORS se realizo de acuerdo con los principios de minima intervendan, que guian los trabajos de conservacian y restau...

The characterisation of atelier materials and of the historical commercial formulation of paint materials has recently gained new interest in the field of conservation science applied to modern and contemporary art, since modern paint materials are subjected to peculiar and often unpredictable degradation and fading processes. Assessing the composition of the original materials purchased by artists can guide not only their identification in works of art, but also their restoration and conservation. Advances in characterisation methods and models for data interpretation are particularly important in studying organic coloring materials in the transition period corresponding to the late 19th-early 20th century, when many such variants or combinations were hypothetically possible in their formulations. There is thus a need for reliable databases of materials introduced in that period and for gaining chemical knowledge at a molecular level related to modern organic pigments, by state-of-the-art protocols. This paper reports on the results of a study on 44 samples of historical colorants in powder and paint tubes, containing both lake pigments and synthetic organic pigments dating from 1890 to 1926. The samples were collected at the Lefranc Archive in Le Mans (France) as a part of Project Futurahma "From Futurism to Classicism (1910Classicism ( -1922. Research, Art History and Material Analysis", (FIRB2012, Italian Ministry of University and Research), and were investigated using an analytical approach based on chromatographic and mass spectrometric techniques. The focus of the chemical analyses was to reveal the composition of the historical organic lake pigments including minor components, to discriminate between different recipes for the extraction of chromophore-containing molecules from the raw materials, and ultimately to distinguish between different formulations and recipes. High performance liquid chromatography (HPLC) with diode array detector (DAD) or electrospray-Quadrupole-Time of Flight tandem mass spectrometry detector (ESI-Q-ToF) were chosen given their considerable capacity to identify such complex and widespread organic materials. Although the inorganic components of the pigments were not taken into account in this survey, the specific molecular profiles provided invaluable information on the extraction procedures or synthetic strategy followed by the different producers, at different times. For instance, the use of Kopp's purpurin and garancine was highlighted, and synthetic by-products were identified. The results provided evidence that the addition of synthetic organic pigments to paint mixtures started from 1910 onwards, but they also suggest that in the formulation of high quality (surfin) colorants, natural products were still preferred. Moreover, in one of the samples the use of murexide as the colouring material was confirmed. This paper presents the first systematic and comprehensive survey on organic lakes and pigments belonging to an historical archive, by both HPLC-DAD and HPLC-ES...

A concise insight into the outputs provided by the latest prototype of visible-near infrared (Vis-NIR) multispectral scanner (National Research Council-National Institute of Optics, CNR-INO, Italy) is presented. The analytical data acquired on an oil painting Madonna of the Rabbit by É. Manet are described. In this work, the Vis-NIR was complemented with X-ray fluorescence (XRF) mapping for the chemical and spatial characterization of several pigments. The spatially registered Vis-NIR data facilitated their processing by spectral correlation mapping (SCM) and artificial neural network (ANN) algorithm, respectively, for pigment mapping and improved visibility of pentimenti and of underdrawing style. The data provided several key elements for the comparison with a homonymous original work by Titian studied within the ARCHive LABoratory (ARCHLAB) transnational access project.

No abstract

The introduction of synthetic dyes and pigments into commerce in the late 19th century was a stimulating time for experimental scientists in their laboratory formulations and for artists in their usage. Nowadays, the period of pioneering syntheses and employment of synthetic organic colouring materials is highly intriguing for scientific research and for conservation purposes in heritage science. In this work, a combination of spectroscopic and chromatographic methods has permitted the elucidation of the chemical composition of 16 early synthetic organic pigment powders from the Lefranc experimental laboratory collection dating 1890-1914. It can be hypothesized that the most successful of these formulations could have been finalized in paint tubes and released onto the market, meaning that they may even be found in artworks from the same period. Specifically, information from this crucial period of transition from the exclusive use of natural dyes/colourants (such as neoflavonoids and plant and insect anthraquinones) to the introduction of their synthetic counterparts (such as synthetic alizarin and purpurin, and acid stable cochineal, together with monoazo and diazo pigments) is confirmed through Raman/surface-enhanced Raman spectroscopy and high-performance liquid chromatography with diode array detection. By means of X-ray fluorescence and mid-Fourier transform infrared spectroscopy, a combination of traditional and modern inorganic substrates has been identified (alum, kaolin, barium sulfate and metallic salts), while Raman has provided additional data regarding the possible complexation of these pigments in the form of lakes