ABSTRACT
Modern art has challenged many aspects of the analytical approaches that are typically used for traditional paint characterization and ageing studies. The paint industry has changed significantly throughout the twentieth century, frequently altering its manufacturing techniques in order to achieve paints with improved appearance, application and performance for a range of diverse household, industrial and artistic uses. This has led to the appearance and use of a multitude of new binding media, pigments and additives, most of which require new analytical methods for their identification. Concrete art is the name given to a significant art movement that took place in Argentina (and other nearby countries) during the 1940s and 1950s, at the exact same time as a flourishing paint industry was utilizing many of these new products and diversifying formulas. This paper reports on some initial findings from a long-term study to develop and apply analytical methodologies on paint samples from a number of Concrete artworks, that will help to better understand art history and advance the conservation field by shedding light on these artist's painting techniques, and the ageing behavior of their materials. Specifically, samples of white paints manufactured by local paint companies in Argentina from that time period were purchased and studied with a multi-analytical approach, which will serve as a reference collection for the field. The analytical techniques used were X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) and gas chromatography coupled with mass spectrometry (GC/MS) with previous derivatization. Artworks samples were studied with a similar multi-analytical approach, and utilized micro-Raman spectroscopy instead of XRD, for its non-destructive application. A wide range of possible compounds was identified due to the complementarity use of analytical techniques, representing a significant first step in Argentinian modern art research.
ABSTRACT
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, ß-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.
ABSTRACT
Cellulose acetate, developed about 100 years ago as a versatile, semisynthetic plastic material, is used in a variety of applications and is perhaps best known as the basis of photographic film stock. Objects made wholly or partly from cellulose acetate are an important part of modern and contemporary cultural heritage, particularly in museum collections. Given the potential instability of the material, however, it is imperative to understand the aging mechanisms and deterioration pathways of cellulose ester plastics to mitigate decomposition and formulate guidelines for storage, exhibition, and conservation. One important aspect of this process is the ability to fully characterize the plastic, because variations in composition affect its aging properties and ultimate stability. In this Account, we assess the potential of a range of analytical techniques for plastics made from cellulose acetate, cellulose propionate, and cellulose butyrate. Comprehensive characterization of cellulose ester plastics is best achieved by applying several complementary analytical techniques. Fourier-transform IR (FTIR) and Raman spectroscopy provide rapid means for basic characterization of plastic objects, which can be useful for quick, noninvasive screening of museum collections with portable instruments. Pyrolysis GC/MS is capable of differentiating the main types of cellulose ester polymers but also permits a richly detailed compositional analysis of additives. Thermal analysis techniques provide a wealth of compositional information and thermal behavior. Thermogravimetry (TG) allows for quantitative analysis of thermally stable volatile additives, and weight-difference curves offer a novel means for assessing oxidative stability. The mechanical response to temperature, such as the glass transition, can be measured with dynamic mechanical analysis (DMA), but results from other thermal analysis techniques such as TG, differential scanning calorimetry (DSC), and dynamic load thermomechanical analysis (DLTMA) are often required to more accurately interpret the results. The analytical results from this study form the basis for in-depth studies of works of art fabricated from cellulose acetate. These objects, which are particularly at risk when stored in tightly sealed containers (as is often the case with photographic film), warrant particular attention for conservation given their susceptibility toward sudden onset of deterioration.
