Phthalocyanine identification in paintings by reflectance spectroscopy. A laboratory and in situ study

Poldi, Gianluca; Caglio, Simone

doi:10.1134/s0030400x13060143

Cited by 27 publications

(28 citation statements)

References 4 publications

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“…Blue 1 has been clearly identified as phthalocyanine blue from both its characteristic UV-Vis-NIR reflectance profile [25,27] and Raman pattern [27] (Fig. 6a, b).…”

Section: Blue Paintsmentioning

confidence: 99%

“…5b in comparison with the reference compound. Another type of green, labelled as green2, has been easily identified as phthalocyanine green, probably in mixture with anatase, by analyzing its vibrational and electronic spectral properties [25,26]: in Fig. 5c, d, examples of Raman and UV-Vis-NIR spectra collected on green2 areas are compared with those from phthalocyanine green powder.…”

Section: Green Paintsmentioning

confidence: 99%

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Disclosing Jackson Pollock’s palette in Alchemy (1947) by non-invasive spectroscopies

et al. 2016

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Alchemy (1947, Peggy Guggenheim Collection, Venice) is one of the most materic works by J. Pollock, whose palette is extensive, ranging from white to yellow, red, green, violet, blue, black, and silver. Each layer of color was laid on top of a previously dried one and effectively separated from the lower one forming a quite complex stratigraphy with colors intersecting each other. In this study, a non-invasive multi-technique method combining point analysis with Vis-NIR multispectral imaging has been exploited to give insights on the painting technique of the American abstract expressionist. The molecular identification of pigments, colorants and extenders contained in fifteen different paints has been achieved combining key spectral markers from elemental, electronic and vibrational spectroscopies. For those colors exhibiting similar hues but different chemical compositions, a mapping procedure based on false color rendering, obtained by properly mixing three spectral planes from the Vis-NIR multispectral imaging set, has been successfully applied. Relevant for the understanding of the evolution of Pollock's drip technique is the identification of both traditional oil-based paints and oil-modified alkyd media. Point analysis by reflection FTIR scattered throughout the painting enabled mapping the distinct use of traditional and new binding media among painted, squeezed and dripped paints.

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“…Blue 1 has been clearly identified as phthalocyanine blue from both its characteristic UV-Vis-NIR reflectance profile [25,27] and Raman pattern [27] (Fig. 6a, b).…”

Section: Blue Paintsmentioning

confidence: 99%

Section: Green Paintsmentioning

confidence: 99%

Disclosing Jackson Pollock’s palette in Alchemy (1947) by non-invasive spectroscopies

et al. 2016

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“…In Figure 4 the bulk color spectra are reported, so that the spectral features can be considered as fingerprints of the commercial colors. In Figure 4a, the PhB spectrum shows a reflectance maximum in the UV-vis range at 460 nm, verifiable in reflectance spectra of different classes of phtalocyanine blue [8], and a weak peak at 660 nm [8]. The weak shoulder centered at about 420 nm can be identified in the reflectance spectrum of the titanium dioxide white [4], indeed present in the composition of the commercial PhB color.…”

Section: Discussionmentioning

confidence: 80%

“…Among the different non-invasive techniques, reflectance spectroscopy has been demonstrated to be a powerful tool in archaeometric studies to identify and characterize modern pigments, with a specific interest for the UV-Vis and infrared (IR) ranges [4][5][6][7][8]. Analog investigations can be performed in the NIR range, where, however, relating the reflectance spectrum of a multi-component artwork to each one of its elements (i.e., support, specific pigment and binder) is not straightforward.…”

Section: Introductionmentioning

confidence: 99%

Detecting the NIR Fingerprint of Colors: The Characteristic Response of Modern Blue Pigments

et al. 2019

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Reflectance spectroscopy in the ultraviolet (UV), visible (Vis), and near infrared (NIR) range is widely applied to art studies for the characterization of paints and pigments, with the advantages of non-invasive techniques. Isolating and detecting the fingerprint of pigments, especially in the NIR range, is quite challenging, since the presence of vibrational transitions of the most common organic functional groups prevents to relate the optical spectrum of a composite sample, as an artwork is, to each one of its elements (i.e., support, binder, and specific pigment). In this work, a method is presented to obtain the UV-Vis-NIR optical response of the single components of a model composite sample reproducing an artwork, i.e., the support, the binder, and the pigment or dye, by using diffuse reflectance spectroscopy. This allowed us to obtain the NIR spectral fingerprint of blue pigments and to identify specific features possibly applicable for detecting cobalt and phthalocyanine blue colors in artwork analysis.

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“…The second measurement was carried out on a two‐layer painted system made of phthalocyanine blue as the bottom layer covered with the red ochre top layer. None of the pigments exhibits significant absorption at the laser excitation wavelength …”

Section: Methodsmentioning

confidence: 99%

Contrasting confocal with defocusing microscale spatially offset Raman spectroscopy

Conti

Realini

Colombo

et al. 2015

J Raman Spectroscopy

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The study compares and contrasts conventional confocal Raman microscopy/spectroscopy (CRM) with a recently developed micrometer scale defocusing spatially offset Raman spectroscopy (micro-SORS), a method providing a new analytical capability for investigating non-destructively the chemical composition of subsurface, micrometer-scale-thick diffusely scattering layers at depths beyond the reach of CRM. Because of close similarities between the two techniques and comparable embodiment of the instrumentations, but radically different interpretations of data, it is crucially important to recognise which type of method is pertinent to a specific measurement. The distinction comes principally from the nature of sample, whether turbid (micro-SORS measurement) or transparent (CRM measurement) on the spatial scale of the axial (z-)scan of the measurement. Which type of sample one deals with may not always be easily recognisable with micro-scale thick layers, and the study therefore also presents a simple method for suggesting whether CRM or micro-SORS methodology applies. This test relies on an axial (z-)scan performed through the sample in both the positive and negative directions from the normal, imaged sample surface position using conventional CRM instrument. The absence or presence of symmetry or asymmetry of the intensity profiles of measured Raman signals around the imaged sample surface position as a function of sample axial displacement then suggests which interpretation could apply. The study paves a way for the development of micro-SORS as a widely applicable analytical tool deployable on conventional Raman microscopes.

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Phthalocyanine identification in paintings by reflectance spectroscopy. A laboratory and in situ study

Cited by 27 publications

References 4 publications

Disclosing Jackson Pollock’s palette in Alchemy (1947) by non-invasive spectroscopies

Disclosing Jackson Pollock’s palette in Alchemy (1947) by non-invasive spectroscopies

Detecting the NIR Fingerprint of Colors: The Characteristic Response of Modern Blue Pigments

Contrasting confocal with defocusing microscale spatially offset Raman spectroscopy

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