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Marquis E.A.,University of Michigan | Chen Y.,University of Michigan | Kohanek J.,University of Michigan | Dong Y.,University of Michigan | Centeno S.A.,The Metropolitan Museum of Art
Corrosion Science | Year: 2015

Preventing the loss of image detail and resolution in historical photographs is a crucial topic, yet the properties of the image particles and mechanisms of deterioration are not fully understood. Through detailed surface and cross sectional analyzes, ungilded and gilded daguerreotypes prepared in the laboratory were analyzed before and after exposure to high sulfur-concentration environments revealing important structural consequences of the gilding process. Comparisons with the surface and sub-surface structures found on a 19th century gilded daguerreotype confirmed the slow corrosion of the underlying Ag and the accumulation of Cu and Ag sulfide particles on the surfaces of the plates. © 2015 Elsevier Ltd. Source

Vila A.,The Metropolitan Museum of Art | Garcia J.F.,University of Barcelona
Analytical Letters | Year: 2012

Prints are one of the most popular artistic forms. They consist of an original matrix that is printed on a paper support. The stamps are part of a series, and each series is composed of a particular number of prints. Many contemporary prints are made using oil inks and synthetic pigments (reds and yellows). Inks are mainly composed of pigments (organic or inorganic) and a binding medium. The analysis of inks has the potential to facilitate and complement the identification of stamps of different origins.Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX) are techniques that are typically available in museums and centers related to the study of works of art. Both can be classified as micro-destructive and provide complementary information about the organic and some inorganic compounds (FTIR), and the elemental composition (SEM-EDX). In this article, the two techniques were used to analyze the composition of red ink in prints. As a result of these analyses, it was possible to distinguish among nearly all of the pigments and inks, indicating that the composition of the red ink can be reliably used to differentiate between stamps of different origins in a series of prints. © 2012 Copyright Taylor and Francis Group, LLC. Source

Holakooei P.,The Metropolitan Museum of Art | Karimy A.-H.,Isfahan University of Art | Hasanpour A.,ICHHTO of Lorestan Province | Hasanpour A.,Islamic Azad University at Tehran | Oudbashi O.,Isfahan University of Art
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2016

This paper reports the results of studies performed on a painted stucco fragment excavated at the Ghaleh Guri in Ramavand, western Iran, and dated back to the late Sasanian period (224–651 AD). Analytical studies including micro-Raman spectroscopy (μ-Raman), micro-X-ray spectrometry (μ-XRF) and optical microscopy showed that red lead and vermilion were used as main pigments on this fragment. Moreover, carbon black was diagnosed to thinly cover some parts of the red lead. Peculiarly, wulfenite (PbMoO4) associated with vanadinite (Pb5(VO4)3Cl) was identified to compose a yellow stain sporadically dispersed on the other pigments. © 2016 Elsevier B.V. Source

Del Federico E.,Pratt Institute | Centeno S.A.,The Metropolitan Museum of Art | Kehlet C.,Pratt Institute | Ulrich K.,Pratt Institute | And 2 more authors.
Applied Magnetic Resonance | Year: 2012

The lead white pigment, 2PbCO 3·Pb(OH) 2, is thought to play a critical role in the degradation of paint in illuminated manuscripts. Cracking, flaking, and separation of paint films containing lead white on parchment and other works of art have been reported, and have been attributed to the interaction of the pigment with the binding media. A previous study by Fourier transform infrared spectroscopy showed lead white to induce a change in the state of hydration of protein-based binders, though the mechanism of this process is still not well understood. In this work, we apply in situ 1H unilateral nuclear magnetic resonance (NMR) to explore the nature of the interaction between lead white and collagen-based binders while at the same time we evaluate the feasibility of applying unilateral 1H-NMR to assess the condition of the paint in medieval-illuminated manuscripts and to follow up the effectiveness of consolidation treatments. Carr, Purcell, Meiboom, and Gill (CPMG) measurements reveal that the addition of lead white to binders derived from collagen, such as bone, rabbit skin or fish glues, increases the T 2eff relaxation constant of these binders. This effect is more pronounced at low relative humidity. The increase in T 2eff suggests that the pigment induces a change in the protein that leads to the formation of more mobile structures, such as peptide fragments, or the partial unfolding of the rigid collagen triple helical structure to a more mobile random coil. The presence of large random coil domains in a collagen-based film has been associated with a lower mechanical strength of the film and therefore with its likeliness to flake. © 2011 Springer-Verlag. Source

Rana V.,John Jay College of Criminal Justice | Canamares M.V.,City College of New York | Kubic T.,John Jay College of Criminal Justice | Leona M.,The Metropolitan Museum of Art | Lombardi J.R.,City College of New York
Journal of Forensic Sciences | Year: 2011

We obtain the normal Raman and surface-enhanced Raman spectrum of three controlled substances: morphine, codeine, and hydrocodone. The spectra are assigned with the aid of density functional theory. Because of rather intense fluorescence, normal Raman spectra suffer from poor signal-to-noise, even when differential subtraction techniques are employed. On the other hand, surface enhancement by Ag nanoparticles both enhances the Raman signal and suppresses the fluorescence, enabling far more sensitive detection and identification. We also present a set of discriminant bands, useful for distinguishing the three compounds, despite the similarities in their structures. © 2010 American Academy of Forensic Sciences. Source

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