Characterization of changes in the chemical composition of aged acrylic resins used in contemporary artworks (original) (raw)
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Analytical and Bioanalytical Chemistry, 2011
This study characterizes and identifies two different acrylic binding media such as Plextol® D498 and Primal® AC33, which are widely used in modern and contemporary art. In order to investigate their fast photooxidative deterioration when exposed to ultraviolet (UV) light, ageing studies on these materials were carried out. For this purpose, pure synthetic materials but also mixed with different inorganic pigments were identified and characterized before and after UV exposure by means of pyrolysis-gas chromatography/mass spectrometry (Py-GC/ MS). Particular attention was paid to the comparison of two different analytical methods: (1) single-shot method based on a pyrolysis for the analysis of polymers and (2) doubleshot method, which allows a unique combination of thermal desorption for the analysis of volatile compounds and pyrolysis of the polymers themselves. These analyses have been complemented by Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) studies. The comparison of the results obtained from unaged samples and UV-aged clearly showed material alterations as well as the formation of new products, which were recorded by FTIR-ATR. Generally, these changes were more pronounced when the acrylic binding media were mixed with pigments. The double-shot technique of Py-GC/MS additionally allowed the detection of the phenolic antioxidant in unaged Plextol® D498, but no oxidation products could be identified by Py-GC/MS in all samples.
Characterization of commercial artists’ acrylic paints and the influence of UV light on aging
International Journal of Polymer Analysis and Characterization, 2017
A large part of Mexican artistic heritage was created with artist's acrylic emulsion paints, so it is crucial to investigate their composition, behavior and decay. Acrylic films are complex chemical systems combining organic and inorganic compounds; therefore, the degradation studies require a variety of techniques. We characterize three acrylic films before and after UV ageing. The relative composition of the polymer matrix was studied by nuclear magnetic resonance (NMR), pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and mass spectrometry with direct analysis in real time (DART-MS).The inorganic compounds and surfaces were characterized by microscopic techniques, such as digital microscopy (DM), scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS) and micro X-Ray diffraction (-XRD).The combined use of these techniques proved to be effective for an in-depth study of the acrylic painting degradation process. The main results were the gradual degradation for the organic surfactant and the loss of inorganic aggregates (talc and carbonates), that led to the Extensive studies on the identification and characterization of these emulsions have been carried out. [3,4,5,6] The two main analytical techniques used were FTIR [7] and Py-GC-MS. [ Error! Bookmark not defined. ] Other less commonly used techniques are the direct thermally-resolved mass spectroscopy (DTMS) [8] and NMR, [ Error! Bookmark not defined. ] the last being ideal for the identification of organic molecules in such paint materials. The surfactants are generally present in low concentrations and they can be either anionic(e.g., sodium lauryl sulfate), cationic(usually based on quaternary ammonium compounds), or nonionic (e.g., alkyl phenol ethoxylates). Non-ionic surfactants, especially those based on polyethoxylates, have been studied in recent years, primarily by their migration to the film surface causing changes in gloss and surface roughness. [9] The main analytical techniques for their study are MS-based techniques, [10,11] several FTIR-based techniques [9,12] and Py-GC/MS. [ Error! Bookmark not defined. ] Many of the artworks with pigmented acrylic emulsions are in outdoor spaces,where ultraviolet (UV) light has an important effect on their photo-oxidative stability. [13,14,15,16] We present the results of a study of three acrylic films,before and after accelerated ageing,by the combined use of techniques: NMR,Py-GC-MS,DART-MS,DM, SEM-EDSand-XRD. EXPERIMENTAL Chemicals / Materials Two of the most used colors in Mexico artworks were chosen: the Toluidine Redand the Hansa Yellow (Politec, Mexico), as well as the unpigmented acrylic binderlike Primal® AC33, (Santiago arte conservación y restauración, Mexico).
2016
The monitoring of performance characteristics of resins was always an issue for the conservation community, since the stability of the art objects depends on the service life of conservation materials used. Among the resins commonly applied in the field of paintings conservation, four of the most popular ones, Paraloid B72, Primal AC33 (acrylic polymers), Ketone Resin N (cyclohexanone) and Laropal A81 (urea-aldehyde) were selected to be comparatively studied under accelerated ageing conditions. These resins have been used by the art conservators either as consolidant materials of the paint or as protecting varnishes for the painting surface. The behaviour of the coatings under thermal ageing was investigated following a methodology depositing films of all materials onto different solid substrates (silicon wafers, quartz and simple glass slides) depending on the method of analysis used. Accelerated thermal ageing tests were conducted at 100 o C, for up to 432 hours. The morphological characteristics of the resins films (crack formations and surface alterations, coherence of film layers, thickness and surface roughness) were examined through scanning electron microscopy (SEM). Chemical changes of the resins were studied with FTIR and UV-Vis spectroscopy, while colour properties and thermal-chemical stability were also studied with spectro-colorimetry. It was found that, although all four displayed changes concerning their colour and film thickness, the two acrylic polymers and the aldehyde resin exhibit high stability against chemical degradation compared to the cyclohexanone based resin. Complementary solubility and swelling testing were also applied and significantly aided in supporting the spectroscopy observations. Finally, microscopic examination of most resin films revealed cracking features which may sometimes render them unsuitable for application under uncontrollable conditions.
Microchemical Journal, 2020
Conservation of contemporary art can be a particularly hard task due to the numerous different techniques and materials adopted by artists worldwide. Due to sampling restriction it is particularly difficult to deeply study the decay mechanism and develop new strategies for their protection. This paper presents results obtained applying a fast and reliable analytical approach to the study of the materials used in Teca con Frutta, by Massimo Zuppelli. The artwork, made in 1967, is a typical example of Arte Povera, realized using materials particularly prone to fast degradation. The choice of accessible and fast analytical techniques such as optical microscopy, micro Fourier transformed infrared spectroscopy (micro-FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) allowed to easily recognize the materials used by the artist as low-density polyethylene spray painted with nitrocellulose and alkyd resin based products. Furthermore, this paper shows how this simple analytical approach made possible to assess the presence of oxidative and biological degradation, which normally require expensive and complicated techniques. These results stress how the application of complementary techniques, associated in a manageable methodology, can provide information of invaluable utility for the study of multi-materials contemporary artworks.
Spectroscopy Letters, 2020
The study is composed of three phases to describe the paintings at normal and several aging times: modeling of new icons similar to an ancient one, aging of the icons by heat and ultraviolet irradiation, and characterization of the icons. The results showed a change in the chemical structure of the painting materials, the crystallinity of the wood and canvas materials, and the chromaticity coordinates with darkening in the heat treatment and fading in the UV irradiation treatment. There is a correlation between the exposure time, the chemical properties of the materials, and the optical properties of the paintings.
Towards more stable natural resin varnishes for paintings
2003
Many of the new insights in the aging processes arose from the use of two analytical methods newly introduced in the field of conservation science: graphite-assisted laser desorption/ionization mass spectrometry (GALDI-MS) and electron paramagnetic resonance spectroscopy (EPR). These two analytical tools are presented in some detail in this Chapter. 2.1 Mass spectrometry Mass spectrometry is an analytical method that separates the components (analytes) of a sample by their molecular masses. To do so, the analytes are brought into the gas phase and ionized. Subsequently, the analytes are separated by their mass and detected. Thus, a mass spectrometer consists of three steps: 1. Ionization (analyte vaporization and ionization) 2. Mass separation 3. Ion detection There are many different ways to accomplish each step, and most of them can be combined according to requirements. However, only the few methods relevant for this thesis will be discussed here, matrix-assisted laser desorption...
Analytical Chemistry, 2009
To characterize a set of synthetic resins, a methodology by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) has been developed. The studied reference materials were commercial versions of a wide range of synthetic resins. For each polymer, the pyrolytic and chromatographic conditions were optimized to adequately resolve the fragment mixture in a short time. The proposed analytical method does not require previous treatment of the sample, and due to its high sensitivity, only a small sample quantity in the microgram range can be used. The pyrolysis temperature was found to have little effect on the obtained pyrograms. The summarized data set for the individual polymer materials, especially the characteristic fragments with a structure close to the monomeric unit, was useful to identify commercial synthetic resins. These materials were used in the art and conservation field, as binding media, paint additives, painting varnishes, coatings, or consolidants. Two case studies are introduced where direct Py-GC/MS and thermally assisted hydrolysis and methylation GC/MS were applied on art objects: first, a modern gluing material of a medieval reverse glass painting, and the second example, the binding medium of a painting by Georg Baselitz ("Senta", 1992/1993) from the Sammlung Moderne Kunst at the Pinakothek der Moderne, Munich.
Journal of Analytical and Applied Pyrolysis, 2002
The ageing behaviour of two diterpenic resins traditionally used as artists' materials, colophony and Venice turpentine, was investigated with different spectroscopic and chromatographic techniques. In particular, three types of ageing (natural, artificial external conditions with a xenon lamp, artificial indoor conditions with fluorescent tubes) were applied to laboratory samples to study their effects on chemical structures. Thermally-assisted hydrolysis and methylation-gas chromatography-mass spectrometry (THM-GC/MS) was employed for careful characterisation and for identification of markers compounds on the vergin resins and in the course of ageing. The most significant changes were detected in the initial part of ageing, and the principal degradation products coming from oxidation, polymerisation and cleavage reactions identified. The high intensity of xenon lamp irradiation was found to cause, apart from oxidation and polymerisation reactions, further degradation of the chemical structure with molecular fragmentation. From the analytical point of view, the differentiation between colophony and Venice turpentine with THM-GC/MS appears to depend on differences in the lower molecular weight resin components.
Conservation Science in Cultural Heritage, 2014
This study is part of a research project dealing with the establishment of monitoring and damage prevention plans for contemporary artworks. For this purpose, some commercial paints, among the most currently used by young artists, were selected: Winton oil paint (Winsor & Newton, UK), Heavy Body acrylic paint (Liquitex, USA) and Flashe vinyl paint (Lefranc & Bourgeois, France). The paints were subjected to different treatments of accelerated ageing, the results indicating different behaviour in relation both to the type of binders and pigments present in the different formulations. In particular, it was observed that ageing produced by ozone plays an important role in the stability of the oil paints, above all in those containing organic azo pigments. Thermal ageing, as expected, influences the stability of all the commercial paints examined, with the formation of alteration products and visible changes in the paint films. Ageing produced by moisture clearly affects the synthetic polymer-based paints, particularly evident in the changes in mass. In all cases, the accelerated ageing treatments produced chromatic variations, more evidently for the oil paints containing organic pigment.
The Study of Binder Aging in 19-21th Centuries Paintings by ATR-FTIR Spectroscopy
The 12th Baltic States Triennial Conservators’ Meeting “Dilemmas. Solutions”, 2020
The analysis of oil and PVAc tempera painting aging by ATR-FTIR spectroscopy was conducted. Correlation between the degree of binder polymerization from the time of painting creation was established. It is shown that ATR-FTIR spectroscopy allows to establish the dating of oil paintings of 19th–21th centuries with the accuracy of 25–35 years.