National Gallery of Art

About: National Gallery of Art is a archive organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Painting & Hyperspectral imaging. The organization has 235 authors who have published 365 publications receiving 5576 citations. The organization is also known as: NGA & Mellon Gallery of Art.

Characterisation of colourants on illuminated manuscripts by portable fibre optic UV-visible-NIR reflectance spectrophotometry

Abstract: The use of ultraviolet and visible diffuse reflectance spectrophotometry as a preliminary technique in the investigation of illuminated manuscripts is discussed. Because ancient manuscripts are amongst the most fragile and precious artworks, characterisation of the materials used in their decoration should be performed using non-invasive analytical methods. Ultraviolet and visible reflectance spectrophotometry with optical fibres (FORS) allows non-invasive identification of several colourants used by ancient illuminators, causing no damage or mechanical stress to the artworks subjected to analysis. Identification is usually based on the comparison of analytical data with a spectral database built from painted areas on parchment, created by preparing paints according to ancient recipes as described in medieval technical treatises. Such database and the spectral features of the colourants analysed are discussed, along with the benefits of extending the spectral range of analysis into the shortwave infrared (to 2500 nm). FORS can be best appreciated as a rapid preliminary tool that offers an overview on the main colourants employed and guides the selection of painted areas of manuscripts on which more selective techniques, such as X-ray fluorescence or Raman spectroscopy, can be employed for a more complete and accurate identification.

New Frontiers in Materials Science for Art Conservation: Responsive Gels and Beyond

Abstract: The works of art and artifacts that constitute our cultural heritage are subject to deterioration, both from internal and from external factors. Surfaces that interact with the environment are the most prone to aging and decay; accordingly, soiling is a prime factor in the degradation of surfaces and the attendant disfigurement of a piece. Coatings that were originally intended to protect or contribute aesthetically to an artwork should be removed if they begin to have a destructive impact on its appearance or surface chemistry. Since the mid-19th century, organic solvents have been the method of choice for cleaning painted surfaces and removing degraded coatings. Care must be taken to choose a solvent mixture that minimizes swelling of or leaching from the original paint films, which would damage and compromise the physical integrity of all the layers of paint. The use of gels and poultices, first advocated in the 1980s, helps by localizing the solvent and, in some cases, by reducing solvent permeation i...

Visible and Infrared Imaging Spectroscopy of Picasso's Harlequin Musician : Mapping and Identification of Artist Materials in Situ

Abstract: Reflection imaging spectroscopy is a useful technique to remotely identify and map minerals and vegetation. Here we report on the mapping and identification of artists' materials in paintings using this method. Visible and infrared image cubes of Picasso's Harlequin Musician are collected using two hyperspectral cameras and combined into a single cube having 260 bands (441 to 1680 nm) and processed using convex geometry algorithms. The resulting 18 spectral end members are identified by comparison with library spectra, fitting by nonlinear mixing, and using results from luminescence imaging spectroscopy. The results are compared with those from X-ray fluorescence spectrometry, polarized light microscopy, and scanning electron microscopy–energy dispersive spectrometry (SEM/EDS). This work shows the potential of reflection imaging spectroscopy, in particular if the shortwave infrared region is included along with information from luminescence imaging spectroscopy.

Reflectance Hyperspectral Imaging for Investigation of Works of Art: Old Master Paintings and Illuminated Manuscripts

Abstract: ConspectusDiffuse reflectance hyperspectral imaging, or reflectance imaging spectroscopy, is a sophisticated technique that enables the capture of hundreds of images in contiguous narrow spectral bands (bandwidth < 10 nm), typically in the visible (Vis, 400–750 nm) and the near-infrared (NIR, 750–2500 nm) regions. This sequence of images provides a data set that is called an image-cube or file-cube. Two dimensions of the image-cube are the spatial dimensions of the scene, and the third dimension is the wavelength. In this way, each spatial pixel in the image has an associated reflectance spectrum. This “big data” image-cube allows for the mining of artists’ materials and mapping their distribution across the surface of a work of art.Reflectance hyperspectral imaging, introduced in the 1980s by Goetz and co-workers, led to a revolution in the field of remote sensing of the earth and near planets (Goetz, F. H.; Vane, G.; Solomon, B. N.; Rock, N. Imaging Spectrometry for Earth Remote Sensing. Science, 1985, ...

Natural resins of art and archaeology their sources, chemistry, and identification

Abstract: The botanical sources and chemical compositions are reviewed of natural resins used, Of likely to have been used, in the fabrication of objects of art and archaeology. They fall into two main chemical groups: those containing diterpenoids—from the order Coniferales and from the Leguminosae family—and those containing triterpenoids from several families of broad-leaved trees. Their chemical compositions, although liable to varying degrees of change with time and exposure, permit them to be identified more or less precisely in favourable cases. Examples of such identifications are described, mostly of conifer resins, using gas-chromatography.