Py-GC/MS applied to the analysis of synthetic organic pigments: characterization and identification in paint samples

A collection of 76 synthetic organic pigments was analysed using pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The purpose of this work was to expand the knowledge on synthetic pigments and to assess characteristic pyrolysis products that could help in the identification of these pigments in paint samples. We analysed several classes of synthetic pigments not previously reported as being analysed by this technique: some metal complexes, β-naphthol pigment lakes, BONA pigment lakes, disazopyrazolone, triarylcarbonium, dioxazine, anthraquinone, indanthrone, isoindoline and thioindigo classes. We also report for the first time the Py-GC/MS analysis of a number of naphthol AS, benzimidazolone, phthalocyanine and perylene pigments and other miscellaneous pigments including pigments with unpublished chemical structure. We successfully used the Py-GC/MS technique for the analysis of paints by artists Clyfford Still and Jackson Pollock to identify the synthetic organic pigments and the binding media

Modern paints

Few would argue that oil paint has been the most important type of paint over the last 500 years. The use of oil as the film-forming component of paint—the binding medium—was well established by the start of the fifteenth century, and for many artists oil paints still remain the preferred choice today. However, throughout the twentieth century a wide and varied range of synthetic polymers have been developed, many of which have been used as binding media in modern paints. The introduction of these synthetic binders, most notably acrylic, alkyd, and polyvinyl acetate, has undoubtedly enabled great advances to be made in paint technology, in terms of reduced yellowing, greater flexibility, faster drying times, and in the case of emulsion formulations, the elimination of organic solvents as thinners and diluents. Many artists have utilized these modern paint types, including those that were never intended specifically for artists’ use, and have explored and exploited their distinct handling and optical properties. Establishing the constituents of paint is frequently necessary prior to any kind of conservation treatment and for developing long-term preventive conservation strategies, as well as for technical art historical studies and issues surrounding authenticity. The identification of binding media is particularly important, as this component appears to have the largest influence on many of the properties of the resulting dried paint film. Although noninvasive/nondestructive techniques would clearly be favorable, at present the most useful analysis is obtained from high-sensitivity techniques that require the removal of submilligram paint samples. Two analytical techniques—pyrolysis-gas chromatography-mass spectrometry (PyGCMS) and Fourier transform infrared spectroscopy (FTIR)—are now routinely used at Tate to identify and characterize modern paints from works of art. This paper will summarize the three principal classes of synthetic binder and how PyGCMS and FTIR have been utilized to analyze them

The Object in Transition: A Cross Disciplinary Conference on the Preservation and Study of Modern and Contemporary Art

Introduction “Since the middle of the twentieth century, artists have increasingly turned to a variety of new materials and techniques for art making. Many of these materials and techniques have produced objects that alter rapidly in appearance and require some level of intervention to enable their continued display. These works pose strong challenges to the fields of conservation and art history. There is often no codified method for conserving such works; further, the insistent but uneven r..

Changes in the surface characteristics of artificially aged mastic varnishes after cleaning using alkaline reagents

This study investigates the effects of a selection of alkaline reagents, including solutions, pastes and soap gels, used to remove an artificially aged mastic film applied over a primed canvas. Surface changes were examined using visible light and scanning electron microscopy (SEM). Ammonia, whether in solution or gelled with hydroxypropylmethylcellulose (HPMC), required a pH of 10 or higher to remove varnish at an appreciable rate, whereas ammonia in wax paste worked at pH 9. Soap gels based on deoxycholic acid (DCA) were effective at pH 9·5. The rate of removal increases significantly with the addition of benzyl alcohol, while anthracene-9-carboxylic acid (A9C) and 9-fluorenone-4-carboxylic acid (9FOC) soap gels of pH 7·9 worked quickly without the addition of alcohol. Where reagents with a pH of more than 9 were used, some erosion of the priming was observed under SEM. Examination of the topography of residual varnish after treatment and Fourier transform infrared spectroscopy (FTIR) measurements provided evidence in support of models for the mode of action of reagents and soap gels on aged varnish. Ammonia, whether in solution, gel or paste, removes varnish by fracturing on a multi-molecular scale; soap gels not -specifically tailored to remove the varnish act similarly. A9C and 9FOC gels remove the varnish by thinning from the upper surface without fracturing

Characterization of artists' acrylic emulsion paints

Commercial waterborne acrylic artists' paints have been characterized with pyrolysis - GC - MS, NMR, size exclusion chromatography and FTIR, and thermogravimetry, for establishing chemical composition, solubility behavior, presence of fillers and additives. In all the pigmented formulations, and in one pure medium, the polymeric base has been invariably found to be formed by different amounts of an ethyl acrylate - methyl methacrylate copolymer. A second acrylic medium revealed the presence of \rm n -butyl acrylate as a third monomer. Pigmented paints were always more difficult to dissolve than pure media, and the occurrence of insoluble material could be demonstrated with titanium white paints. Inorganic components and other additives present in the paint formulations are expected to have some influence on the chemical and molecular evolution of the paints with aging

Conservation Concerns for Acrylic Emulsion Paints: A Literature Review

Acrylic emulsion paints have been widely used by artists since their development in the late 1950s. This paper reviews the conservation information that currently exists about them. Brief descriptions are given of their development and how they are analysed, but the focus of this review is on current conservation concerns about their physical properties, how they will age and the effects of cleaning