An integrated analytical study of crayons from the original art materials collection of the MUNCH museum in Oslo.

Among the artists' materials of the nineteenth century, pastel crayons merit scientific interest since their early commercial formulations are mostly unknown and, until now, have been considerably less studied with respect to other contemporary painting materials. In this framework, research herein reports the results of a comprehensive multi-analytical study of 44 pastel crayons of two recognized brands (LeFranc and Dr. F. Schoenfeld) from the Munch museum collection of original materials belonging to Edvard Munch. The integrated use of complementary spectroscopic and hyphenated mass-spectrometry techniques allowed the compositional profiles of the crayons to be traced providing the identification of the inorganic and organic pigments, the fillers/extenders and the binders. All crayons resulted to be oil- based and the binder was identified to be a mixture of a drying oil (safflower or linseed oil), palm oil or Japan wax and beeswax. Among others, pigments such as ultramarine, chrome yellows, Prussian blue, manganese violet, viridian and madder lake have been identified. A significant alignment in formulations of the brands was observed with the only exception of the greens which showed distinctive pigment and filler compositions. The analytical information provided for these commercial artists' materials will be of great interest for academia, museum and other institutions hosting art collections dating from the same period and it will be used by the Munch museum to draw proper conservation strategies of its own artwork collections.

Probing the chemistry of CdS paints in The Scream by in situ noninvasive spectroscopies and synchrotron radiation x-ray techniques.

The degradation of cadmium sulfide (CdS)-based oil paints is a phenomenon potentially threatening the iconic painting The Scream (ca. 1910) by Edvard Munch (Munch Museum, Oslo) that is still poorly understood. Here, we provide evidence for the presence of cadmium sulfate and sulfites as alteration products of the original CdS-based paint and explore the external circumstances and internal factors causing this transformation. Macroscale in situ noninvasive spectroscopy studies of the painting in combination with synchrotron-radiation x-ray microspectroscopy investigations of a microsample and artificially aged mock-ups show that moisture and mobile chlorine compounds are key factors for promoting the oxidation of CdS, while light (photodegradation) plays a less important role. Furthermore, under exposure to humidity, parallel/secondary reactions involving dissolution, migration through the paint, and recrystallization of water-soluble phases of the paint are associated with the formation of cadmium sulfates.

Assessment of cleaning effectiveness for new ecological systems on ancient tempera icon by complementary microscopy techniques.

The study presents an old icon painted in egg tempera on lime wood, with a poor conservation condition and clogged dirt deposits. The icon is attributed to an anonymous painter of XIXth century and to the neo-classical style of painting. The painting layer was done with only a hand full of pigments, earth colors that were often used in painting the icons from XVIIth to XIXth century in Eastern Europe, that have Byzantine influences. Taking into consideration the nature and the structure of the materials from the upper layers of the painting, affected by deposits of dirt over time, a series of cleaning recipes were studied, using the so called cleaning tests with compatible mixtures of different juices and infusion from indigenes plants, that were freshly done and odorless. A low alkaline 95% ethyl alcohol solution, combined with a few drops of ammoniac 25%, was used as a reference system, due to its compatibility with the greasy deposits found on the polychrome layer and on the wood. The cleaning capacity of the new systems used, in comparison with the standard solution, was analyzed through modern analytical methods of evaluating the degree of cleaning, more exactly by means of visible and UV reflectography, CIE L*a*b* colorimetry by reflection assisted by SEM-EDX and IR spectroscopy.

Assessment of green cleaning effectiveness on polychrome surfaces by MALDI-TOF mass spectrometry and microscopic imaging.

This article proposes an innovative methodology which employs nondestructive techniques to assess the effectiveness of new formulations based on ionic liquids, as alternative solvents for enzymes (proteases), for the removal of proteinaceous materials from painted surfaces during restoration treatments. Ionic liquids (ILs), also known as "designer" solvents, because of their peculiar properties which can be adjusted by selecting different cation-anion combinations, are potentially green solvents due totheir low vapour pressure. In this study, two ionic liquids were selected: IL1 (1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4 ])) and IL2 (1-ethyl-3-methylimidazolium ethylsulphate ([EMIM][EtSO4 ])). New formulations were prepared with these ILs and two different proteases (E): one acid (E1-pepsin) and one alkaline (E2-obtained from Aspergillus sojae). These formulations were tested on tempera and oil mock-up samples, prepared in accordance with historically documented recipes, and covered with two different types of protein-based varnishes (egg white and isinglass-fish glue). A noninvasive multiscale imaging methodology was applied before and after the treatment to evaluate the cleaning's effectiveness. Different microscopic techniques-optical microscopy (OM) with visible and fluorescent light, scanning electron microscopy (SEM) and atomic force microscopy (AFM)-together with Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) were applied on areas cleaned with the new formulations (IL + E) and reference areas cleaned only with the commercial enzyme formulations (gels). MALDI-TOF proved particularly very useful for comparing the diversity and abundance of peptides released by using different enzymatic systems. Microsc. Res. Tech. 77:574-585, 2014. © 2014 Wiley Periodicals, Inc.

Nondestructive characterization and enzyme cleaning of painted surfaces: assessment from the macro to nano level.

This work establishes a multiscale and multitechnique nondestructive approach as valid methodology for monitoring surface properties and evaluating the effectiveness of enzymatic removal of varnishes from paintings/polychrome artefacts. Mock-up samples (documented reconstructions of oil, tempera, and gilded layers on canvas and wooden supports) were covered with different proteinaceous varnishes (egg white, animal and fish glue, casein) and then characterized before and after the removal of these coatings with enzyme-based solutions. The varnish was cleaned in several steps (two dry swabs and two wet swabs) with a clearance step for removing the residues from proteinaceous varnish or from enzyme solution. Microscopy [stereomicroscopy (SM), optical microscopy (OM), atomic force microscopy (AFM), and scanning electron microscopy (SEM)] and colorimetric (CIE L*a*b* system) techniques were used for characterization of the reconstruction surfaces at different scales (macro-scale by SM and OM; micro-scale by SEM and nano-scale by AFM). These techniques were also used to monitor the cleaning treatment. Although results presented in this work were obtained for the specific treatment of enzyme removal, the methodology could be extended to other types of materials and cleaning. Further experiments on real works of art are needed for a complete validation of the methodology.

An innovative, interdisciplinary, and multi-technique study of gilding and painting techniques in the decoration of the main altarpiece of Miranda do Douro Cathedral (XVII-XVIII(th) centuries, Portugal).

The research results presented in this paper are part of a larger study on the materials and techniques used in polychrome altarpieces of gilded woodcarving decoration ("talha dourada") in Portugal. The paper focuses on a narrative Portuguese Altarpiece from Miranda do Douro, considered one of the masterpieces of "talha dourada" among all the retables of the Iberian Peninsula in XVII(th) and XVIII(th) centuries. Although on the Portuguese territory, the altarpiece was made by artists from the Royal Spanish school of Valladolid, under a mannerist style. Thus the study opens a window on the artists' circulation between Spain and Portugal and influences of the Spanish schools in Baroque epoch on the Portuguese "talha". During its history this altarpiece underwent several transformations and extensive conservation treatments in 1989. On this occasion more than 50 samples were collected and analyzed using an interdisciplinary multi-technique methodology. 27 of these samples are chosen for this study in order to investigate the chromatic palette, the materials and techniques used in the polychromy of the retable. A novel protocol of investigation using different conventional and unconventional analytical techniques (OM + fluorescent staining tests on cross-sections, Raman microscopy, XRD, XRF, X-ray micro-CT, SEM-EDX, MALDI-TOF-MS and LC-MS/MS) was established within an innovative research project (http://sites.fct.unl.pt/gilt-teller/) and applied on these samples. This protocol is necessary to confirm the results obtained in the 1989 campaign and to have further insight into the gilding and polychrome decoration materials and techniques and the additional information reported in the historical documents. The material and technical history of this important altarpiece will be thus re-documented from a scientific perspective, meant to confirm and bring new information on the decorative technique used in the creation of this complex Portuguese monument.

Cross-section and staining-based techniques for investigating organic materials in painted and polychrome works of art: a review.

The article presents a review of the use of cross-section and staining techniques for investigating natural organic materials (mainly proteinaceous and oil-based binders/varnishes) in painted and polychrome artworks, considering the requirements of conservation practice and routine diagnostics. The reviewed literature calls attention to the importance of using cross sections to prepare samples for optical microscopy and to different properties of embedding resins; the most appropriate instrumental conditions for optical microscopy; and the advantages and disadvantages of the most common staining techniques. A few case studies were selected to illustrate the use of autofluorescence (intrinsic fluorescence) and induced fluorescence (using specific staining tests and fluorophore-labeled antibodies) for mapping and identifying organic paint materials in cross sections. New directions of research in cross-section analyses and fluorescence-based techniques for the identification and mapping of artistic materials are presented. The complementary use of different stains on the same cross section, further exploration of intrinsic and induced fluorescence of aged versus fresh materials, and applicability of cross-section observation and staining as complementary methods for assessing the effectiveness of restoration treatments, such as cleaning and consolidation, are discussed in the last section of the article.

Integrated methodology for the evaluation of cleaning effectiveness in two Russian icons (16th-17th centuries).

This article covers a methodology for evaluating the effectiveness of cleaning two Russian icons. The icons belong to a group of five from the same iconographic school, dating from the 16th to 17th centuries. An integrated and complementary approach to varnish and overpaint removal involved microscopic techniques (optical and scanning electron microscopy) and colorimetry (CIE L*a*b* system). The materials and techniques used in these icons have been characterized previously. Cleaning revealed extensive overpainting that had not only dramatically changed the original appearance, but also the meaning and attribution of one of the two icons. The analyses carried out were useful in determining the extent of the overpainting and led to a better assessment of the results and effectiveness of the restoration.

Integrated analytical study for the authentication of five Russian icons (XVI-XVII centuries).

This article presents an integrated approach for the authentication of five Russian icons through the study of their paint materials (elemental composition and stratigraphic mapping), state of conservation and artistic technique. The results of the applied analytical protocol, involving optical and scanning electron microscopy coupled with energy-dispersive X-ray spectrometry and Fourier transformed infrared spectroscopy/microspectroscopy, led to the conclusion that the five icons belong to the same group and iconographic school (from Northern Russia) and date from the end of the 16th century to the beginning of 17th century. Because of massive overpainting, the icons "suffered" a change in iconographic style and significance, and restoration treatment brought to light the original painting and its attribution. Identification of the composition of the original chromatic palette used by the iconographer, the stratigraphic mapping and the conservation state of the painting materials, along with the features of the original artistic technique, furnished key elements for the icons' authentication. Here, we present the first experimental data concerning the identification of the authentication characteristics, being part of a large project that has as its final aim the evaluation of the effectiveness and effects of the cleaning agent on the paint layers.