Cleaning painted surfaces of their grime, aged varnishes, and discolored overpaint is one of the ... more Cleaning painted surfaces of their grime, aged varnishes, and discolored overpaint is one of the most common interventive treatments for art conservators. Carefully concocted solvent mixtures navigate the solubility differences between the material removed and the original paint underneath. However, these solutions may be altered by differential evaporation rates of the component solvents (zeotropic behavior), potentially leading to ineffectively weak cleaning or conversely overly strong residual liquid capable of damaging the underlying paint. Azeotropic solvent blends, which maintain a constant composition during evaporation, offer a promising solution. These blends consist of two or more solvents combined at precise concentrations to function as a single solvent. Additionally, pressure-maximum azeotropes feature higher vapor pressure compared to other mixtures, further minimizing contact time and sorption of the solvents into artworks. This study examines azeotropes of isopropano...
Solvent mixtures are often fine-tuned by art conservators for the difficult tasks of safely remov... more Solvent mixtures are often fine-tuned by art conservators for the difficult tasks of safely removing yellowed varnishes and obfuscating dirt from oil paintings. These two goals are often loosely termed " picture cleaning. " Concern has been raised over the impact of differential evaporation rates for solvents in the cleaning mixture. Differential evaporation can lead to changes in the mixture's potency over time and potentially lead to solvent mixtures on the surface of the artwork having solubility characteristics deleterious to artists' oil paints. Azeotropic mixtures of solvents have been proposed as an alternative for maintaining consistent solvent composition. Azeotropes are specific mixtures of two or more solvents that behave as a single solvent and maintain a constant composition at their boiling point. The azeotropes that have appeared in the art conservation literature are taken from tables of azeotropic compositions in the CRC Handbook given at their boi...
Proceedings of the National Academy of Sciences, 2019
Significance Can radiocarbon ( 14 C) dating uncover modern forgeries? Radiocarbon dating has the ... more Significance Can radiocarbon ( 14 C) dating uncover modern forgeries? Radiocarbon dating has the potential to answer the question of when an artwork was created, by providing a time frame of the material used. In this study we show that with two microsamples (<500 μg), from both the canvas and the paint layer itself, a modern forgery could be identified. The canvas dating is consistent with the purported attribution to the 19th century; however, the 14 C age gained on the paint contradicts this as it offers clear evidence for a post-1950 creation. Thus the additional dating of the paint reveals the forger’s scheme where the repainting of an appropriately aged canvas was used to convey the illusion of authenticity.
We have recently demonstrated that exfoliated Egyptian blue powder coated with cetrimonium bromid... more We have recently demonstrated that exfoliated Egyptian blue powder coated with cetrimonium bromide is effective for detecting latent fingermarks on a range of highly-patterned non-porous surfaces (see reference). In this extension of that work, we here present our preliminary studies into alternative approaches to preparing exfoliated Egyptian blue with a variety of different coatings. The various powders were then applied to the detection of latent fingermarks on non-porous surfaces. This proof of concept study demonstrated that there is potential improvement in performance compared to our previous work, however more comprehensive studies are required to compare the quality of the fingermarks developed with these powders against particles exfoliated in water.
... of the brown-black painted surfaces of sherds C (analysed earlier by FTIR microscopy) and L .... more ... of the brown-black painted surfaces of sherds C (analysed earlier by FTIR microscopy) and L ... Its presence was revealed here because the analysis could be focused selectively through a ... nature of the iron-containing material could be specified because Raman spectroscopy is a ...
Museum professionals must ensure that protective enclosures for artworks do not in fact cause dam... more Museum professionals must ensure that protective enclosures for artworks do not in fact cause damage to the objects within due to pollution off-gassing from the container’s components. Ideally, all materials used in proximity to artworks should be assessed for their potential to emit harmful volatiles. The standard approach used in the museum field, known as the Oddy test, requires significant effort and time and can produce unreliable results if not conducted by a trained staff member, all of which reduce the likelihood that proper vetting will be rigorously employed. This paper reports a methodology utilizing a microfurnace pyrolyzer coupled to a gas chromatograph with a mass spectrometer to optimize these assessments and produce actionable results with minimal time and expense. Simple confirmatory chemical tests augment the direct thermal desorption (DTD) experiment, and as a last resort, time-consuming accelerated aging tests are utilized if deemed necessary to eliminate or deci...
Cleaning painted surfaces of their grime, aged varnishes, and discolored overpaint is one of the ... more Cleaning painted surfaces of their grime, aged varnishes, and discolored overpaint is one of the most common interventive treatments for art conservators. Carefully concocted solvent mixtures navigate the solubility differences between the material removed and the original paint underneath. However, these solutions may be altered by differential evaporation rates of the component solvents (zeotropic behavior), potentially leading to ineffectively weak cleaning or conversely overly strong residual liquid capable of damaging the underlying paint. Azeotropic solvent blends, which maintain a constant composition during evaporation, offer a promising solution. These blends consist of two or more solvents combined at precise concentrations to function as a single solvent. Additionally, pressure-maximum azeotropes feature higher vapor pressure compared to other mixtures, further minimizing contact time and sorption of the solvents into artworks. This study examines azeotropes of isopropano...
Solvent mixtures are often fine-tuned by art conservators for the difficult tasks of safely remov... more Solvent mixtures are often fine-tuned by art conservators for the difficult tasks of safely removing yellowed varnishes and obfuscating dirt from oil paintings. These two goals are often loosely termed " picture cleaning. " Concern has been raised over the impact of differential evaporation rates for solvents in the cleaning mixture. Differential evaporation can lead to changes in the mixture's potency over time and potentially lead to solvent mixtures on the surface of the artwork having solubility characteristics deleterious to artists' oil paints. Azeotropic mixtures of solvents have been proposed as an alternative for maintaining consistent solvent composition. Azeotropes are specific mixtures of two or more solvents that behave as a single solvent and maintain a constant composition at their boiling point. The azeotropes that have appeared in the art conservation literature are taken from tables of azeotropic compositions in the CRC Handbook given at their boi...
Proceedings of the National Academy of Sciences, 2019
Significance Can radiocarbon ( 14 C) dating uncover modern forgeries? Radiocarbon dating has the ... more Significance Can radiocarbon ( 14 C) dating uncover modern forgeries? Radiocarbon dating has the potential to answer the question of when an artwork was created, by providing a time frame of the material used. In this study we show that with two microsamples (<500 μg), from both the canvas and the paint layer itself, a modern forgery could be identified. The canvas dating is consistent with the purported attribution to the 19th century; however, the 14 C age gained on the paint contradicts this as it offers clear evidence for a post-1950 creation. Thus the additional dating of the paint reveals the forger’s scheme where the repainting of an appropriately aged canvas was used to convey the illusion of authenticity.
We have recently demonstrated that exfoliated Egyptian blue powder coated with cetrimonium bromid... more We have recently demonstrated that exfoliated Egyptian blue powder coated with cetrimonium bromide is effective for detecting latent fingermarks on a range of highly-patterned non-porous surfaces (see reference). In this extension of that work, we here present our preliminary studies into alternative approaches to preparing exfoliated Egyptian blue with a variety of different coatings. The various powders were then applied to the detection of latent fingermarks on non-porous surfaces. This proof of concept study demonstrated that there is potential improvement in performance compared to our previous work, however more comprehensive studies are required to compare the quality of the fingermarks developed with these powders against particles exfoliated in water.
... of the brown-black painted surfaces of sherds C (analysed earlier by FTIR microscopy) and L .... more ... of the brown-black painted surfaces of sherds C (analysed earlier by FTIR microscopy) and L ... Its presence was revealed here because the analysis could be focused selectively through a ... nature of the iron-containing material could be specified because Raman spectroscopy is a ...
Museum professionals must ensure that protective enclosures for artworks do not in fact cause dam... more Museum professionals must ensure that protective enclosures for artworks do not in fact cause damage to the objects within due to pollution off-gassing from the container’s components. Ideally, all materials used in proximity to artworks should be assessed for their potential to emit harmful volatiles. The standard approach used in the museum field, known as the Oddy test, requires significant effort and time and can produce unreliable results if not conducted by a trained staff member, all of which reduce the likelihood that proper vetting will be rigorously employed. This paper reports a methodology utilizing a microfurnace pyrolyzer coupled to a gas chromatograph with a mass spectrometer to optimize these assessments and produce actionable results with minimal time and expense. Simple confirmatory chemical tests augment the direct thermal desorption (DTD) experiment, and as a last resort, time-consuming accelerated aging tests are utilized if deemed necessary to eliminate or deci...
As part of an ongoing effort to understand the weaving technology of nomadic people in Central As... more As part of an ongoing effort to understand the weaving technology of nomadic people in Central Asia, chemical analyses were performed on wool fibers taken from a prayer rug and a luxury bag known as a chanteh from the Jason Deighton-Sarzetakis Baluch collection (Corfu Museum of Asian Art) in order to identify the dyestuff used to create certain red and yellow fields. The fiber samples were extracted into organic solvents, which were then analyzed by Liquid Chromatography-Diode Array Detection-Mass Spectrometry (LC-DAD-MS). Colorants from such natural dyestuff as cochineal, madder (Rubia tinctorum) and gall nut, along with the synthetic dye Acid Yellow 36 (Metanil yellow) have been identified in specimens from the Sarzetakis collection. The use of cochineal, a costly and luxurious dyestuff, increases the value and significance of the prayer rug. Moreover, 1879 the year of invention of Acid Yellow 36, provides a terminus post quem for the creation of the chanteh. The pilot study of these nomadic artifacts from the first ever documented Bal-uch collection in Greece will contribute to understanding the profile of their unknown creators and assist in the heritage management of the so called Baluch works within museums.
A translated and updated version of the paper in Greek presented at the Annual Meeting of Panhellenic Association of Conservators of Antiquities, 03-12-2016, Athens.
Translation: Kassiani Kagouridi, Editing: Victor J. Chen and Gregory D. Smith, Proofreading: Chryssa Panagiotopoulou.
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Papers by Gregory D Smith
A translated and updated version of the paper in Greek presented at the Annual Meeting of Panhellenic Association of Conservators of Antiquities, 03-12-2016, Athens.
Translation: Kassiani Kagouridi, Editing: Victor J. Chen and Gregory D. Smith, Proofreading: Chryssa Panagiotopoulou.