Nondestructive Varnish Identification by Ultraviolet Fluorescence Spectroscopy

Thoury, Mathieu; Elias, Mady; Frigerio, Jean Marc; Barthou, Carlos

doi:10.1366/000370207783292064

Cited by 41 publications

(29 citation statements)

References 9 publications

(9 reference statements)

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“…The DLE band is already used as a common probe to localize the presence of zinc white on paint surfaces by means of UVfluorescence imaging techniques. [14][15][16] This widespread practice may result in misleading interpretations due to the low specificity of the visible luminescence that may be overlapped with binder, 14 varnish, 17 and/or yellow dye emissions. 18 Higher specific and reliable characteristics may be provided by the excitonic emission band, as already highlighted on model samples and real paintings.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence Properties of Zinc Oxide in Paints: A Study of the Effect of Self-Absorption and Passivation

et al. 2012

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Zinc oxide has been widely used as a white artist pigment since the end of the eighteenth century. The luminescence properties of this compound have received great interest during the last decades for promising applications in different fields of material science, but their diagnostic implications in the cultural-heritage context have been poorly exploited. This paper is intended to provide a clear picture of the luminescence behavior of zinc white in oil paintings. With this aim, three white pigments and three highly pure (analytical grade) zinc oxides were studied as powder substrates and as painting models by ultraviolet-visible (UV-VIS) fluorescence and Fourier transform infrared (FT-IR) spectroscopy. The quenching of the luminescence intensity of the UV excitonic emission due to self-absorption and multiple scattering phenomena has been investigated, pointing out the possible difficulty of detecting this signal with negative consequences in the diagnostics of works of art. By contrast, the UV emission is notably enhanced by interaction with the binder, whereas the visible emission decreases. This phenomenon is probably due to the formation of covalent bonds between zinc atoms and carboxylates from the lipidic medium that are chemisorbed on zinc oxide surfaces.

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Section: Introductionmentioning

confidence: 99%

Photoluminescence Properties of Zinc Oxide in Paints: A Study of the Effect of Self-Absorption and Passivation

et al. 2012

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“…Fluorescence intensity was strongly lower for layer 2 applied over the silver leaf in comparison to the thicker varnish on top (i.e., layer 1), thus suggesting that layer 2 was more aged and ancient. As witnessed by the narrower FWHM, varnish layer 1 is instead more representative of a less complex and aged composition [13]. Unlike varnish layer 2, the blue-shifted fluorescence of the uppermost varnish layer 1 could match more plausibly with a yellow oil medium glaze, but it is rather difficult to obtain more detailed information.…”

Section: Resultsmentioning

confidence: 99%

“Argento Deaurato” or “Argento Biancheggiato”? A Rare and Interesting Case of Silver Background in Italian Painting of the XIII Century

et al. 2020

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The painting depicting the “Virgin with the Child and two angels” by a Tuscan anonymous artist of the XIII century, has raised great interest regarding the execution technique including the use of silver, applied on wood as a background. An in-depth investigation was carried out especially concerning the burnishing process of the silver leaves as well as a detailed inspection of the nature of the organic compounds over the metal leaf and the degradation products of the silver layer. To this aim, a multianalytical approach was used including UV–VIS microscopy along with an Ultra-High-Resolution Scanning Electron Microscopy (UHR-SEM), as well as Fourier Transform Infrared (FTIR), fluorescence and micro-Raman spectroscopies. As a result, the presence of an oil-resin varnish layer in the uppermost layer and a wax-protein layer between the varnish and the metal layer as well as the evidence that the silver leaf was applied with high accuracy directly to the preparation layer, were clearly demonstrated. Furthermore, degradation products of the silver leaf were identified as sulphides, chlorides, and oxides. The holistic approach herein adopted enabled a step forward in the knowledge of the 13th century silver leaf gilding technique, adding value to the originality of this artwork. In this respect, the scientific evidence led to the assumption that likely this painting originally showed a silver-colored background (“argento biancheggiato”) as compared to the initial theory of a case of “argento deaurato”.

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“…The band may be shifted by aging, and be associated to oxidation processes that generate fluorescent molecules. It is possible that the recipe, and the type of varnish used could affected the signal observed [51]. Those signals could be related to previous restorations.…”

Section: Resultsmentioning

confidence: 99%

Discovery of Vespasiano Bignami paintings at the National Theatre of Costa Rica through technical photography and UV–Vis spectroscopy

et al. 2020

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Establishing and understanding large format paintings are key to provide accurate information about the artist’s palette and developing conservation strategies. Therefore, investigating the artworks of a population offers insight into its culture, history and origins which reveals individual and collective identity through cultural heritage worldwide. Particularly, the ceiling of the Foyer at the National Theatre of Costa Rica (Central America) is decorated with three large format paintings from the nineteenth century made by the Italian painter Vespasiano Bignami. The paintings are known as La Poesía, La Música and La Danza (The Poetry, the Music and The Dance) and have undergone restorations in the past. However, their state of conservation is unknown and thus demands accurate scientific examination in order to document their status and the extent of undocumented previous restoration work. To overcome those issues, we propose the application of a combination of non-invasive and in-situ techniques to carry out a qualitative assessment of the pigments and actual state of conservation. Here, we employed technical photography in the visible and near infrared regions, using panoramic stitching techniques in order to obtain high resolution images of the very large artworks. Several conservation problems were observed such as: detachment of pigments, cracks, stains, and sections with undocumented restorations. In the IR and False Colour Infrared images we observed a very conspicuous behaviour of the red pigment used in the three paintings. Particular areas with the red pigment were fluorescent, and by means of ultraviolet fluorescence imaging we identified the pigment as through its red-coral fluorescence as Madder Lake, by comparison to a historical pigments reference palette. Measurements in five different red pigmented zones using UV–Vis spectroscopy in The Music show bands in the (550–650) nm region. A Lorentz Model nonlinear curve fit to the bands allowed us to correlate the fluorescent pigment in the paintings of Vespasiano Bignami with Madder Lake.

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Nondestructive Varnish Identification by Ultraviolet Fluorescence Spectroscopy

Cited by 41 publications

References 9 publications

Photoluminescence Properties of Zinc Oxide in Paints: A Study of the Effect of Self-Absorption and Passivation

Photoluminescence Properties of Zinc Oxide in Paints: A Study of the Effect of Self-Absorption and Passivation

“Argento Deaurato” or “Argento Biancheggiato”? A Rare and Interesting Case of Silver Background in Italian Painting of the XIII Century

Discovery of Vespasiano Bignami paintings at the National Theatre of Costa Rica through technical photography and UV–Vis spectroscopy

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