Narayan Khandekar

Comparison of three-dimensional optical coherence tomography and high resolution photography for art conservation studies

Gold punchwork and underdrawing in Renaissance panel paintings are analyzed using both three-dimensional swept source / Fourier domain optical coherence tomography (3D-OCT) and high resolution digital photography. 3D-OCT can generate en face images with micrometer-scale resolutions at arbitrary sectioning depths, rejecting out-of-plane light by coherence gating. Therefore 3D-OCT is well suited for analyzing artwork where a surface layer obscures details of interest. 3D-OCT also enables cross-sectional imaging and quantitative measurement of 3D features such as punch depth, which is beneficial for analyzing the tools and techniques used to create works of art. High volumetric imaging speeds are enabled by the use of a Fourier domain mode locked (FDML) laser as the 3D-OCT light source. High resolution infrared (IR) digital photography is shown to be particularly useful for the analysis of underdrawing, where the materials used for the underdrawing and paint layers have significantly different IR absrption properties. In general, 3D-OCT provides a more flexible and comprehensive analysis of artwork than high resolution photography, but also requires more complex instrumentation and data analysis.

Preparation of cross-sections from easel paintings

Abstract The literature related to the making of paint crosssections taken from easel paintings spans a range of issues, from the reasoning and justification for sampling and sampling methods to sample mounting, grinding and polishing, analytical techniques and long-term degradation. This review places the preparation of cross-sections into an overall strategy for the examination of painted surfaces.

An Egyptian Cartonnage of the Graeco-Roman Period

Abstract Technical and analytical studies were carried out on a late Graeco/early Roman Egyptian cartonnage from the University of Southern California (USC 9428). The structure of the object was visually examined, and the layers of textile and plaster were identified as linen, wood fibres of mixed origin, and a lime-based plaster. Using a combination of techniques, the pigments used to decorate the cartonnage were identified as minium, Egyptian blue, green earth, a copper proteinate green, a mixture of Egyptian blue and iron ochres, a mixture of green earth and Egyptian blue, orpiment, hydrocerussite, a lac dye and a carbon lamp-black. The discovery of previously unrecognized and apparently rare pigments, such as a copper proteinate pigment from 350 BC, suggests that there is still much work to be done on the use of pigments and the techniques of painting and cartonnage production.

A survey of the conservation literature relating to the development of aqueous gel cleaning on painted and varnished surfaces

Abstract A brief overview of cleaning controversies illustrates the importance for control during the cleaning of paintings. In the mid-1980s Richard Wolbers introduced a gelled aqueous system in response to the need for increased control, as an alternative to cleaning with free solvents. A chronological survey of the conservation literature related to aqueous gel cleaning follows. The paper concludes with an outline of a current research project examining the problem of residues and gel clearance.

The evolution of Lucio Fontana's painting materials

Abstract The study focuses on the range of pigments and media that the Italian artist Lucio Fontana (1899–1968) employed for selected works dating between 1949 and 1968. Samples were taken from ten groups of works, all on canvas support, as well as from painting equipment that survived in the artists former two studios. Techniques of analysis used were pyrolysis-gas chromatography–mass spectrometry for media identification, and laser desorption ionization time-of-flight mass spectrometry and Raman microspectroscopy for pigment identification. Fontanas reputation as a daring and experimental artist, best known for his group of slashed paintings called tagli, is seen to correspond with certain unusual material choices he made. The study also points to several links that exist between seemingly unrelated cycles. These links are, among others, based on experiences with in part novel media such as oil, alkyd, polyvinyl acetate, acrylic, acrylic–vinyl, and mixtures of them. With regard to pigments, the selection of samples showed that they were mostly of a synthetic organic nature.

Materials and Techniques of a Spanish Renaissance Panel Painting

Abstract A technical examination of a Spanish altarpiece attributed to Bartolomé Bermejo (1468–1495), belonging to the Hispanic Society of America, was carried out. Analytical methods used in this study were X-radiography, infrared reflectography, optical microscopy (reflected light and polarized light), cross-section staining tests, scanning electron microscopy, gas chromatography–mass spectrometry, Fourier transform infrared spectroscopy and carbon-14 dating. A number of unusual techniques were identified including: the use of cotton and flax fibres for internal strength in the halo relief, the lack of a bole layer, the use of an orangecoloured oil mordant under the gilding, the use of powdered gold over the entire gilded surface and the use of an egg-white binding medium. The carbon-14 dating placed the panel in the 1530s, which will lead to a new attribution.

The making of Mark Rothko's Harvard Murals

Mark Rothkos Harvard Murals are a series of paintings on canvas commissioned by Harvard University and created in the early 1960s. The present study investigates Rothkos creative process, materials, and technique with ultraviolet and infrared imaging, analytical chemistry, cross-sectional analysis, and comparisons with the literature. Infrared and Raman spectroscopy imaging of cross sections help with the chemical mapping of the paint stratifications. A comparison of paper studies, studies on canvas, and the final five works installed give a detailed insight into Rothkos editing process. The intimate relationship between works on paper and canvas is traced by uncovering a back and forth between the two media, and the mixing of dry pigment with binder is a common theme for works on both supports. Motif developments, changes, and distinct painting campaigns become apparent with ultraviolet induced visible fluorescence imaging and infrared reflected infrared digital photography. Color measurements and microfading experiments give insight into the stability and light sensitivity of the materials used by Rothko in the Harvard Murals.

Conservation of a room: A treatment proposal for Mark Rothko's Harvard Murals

A treatment with projected light for Mark Rothkos Harvard Murals (1962) is proposed. The group of five paintings on canvas has changed color due to the presence of a fugitive red pigment and excessive exposure to natural light in a room with large windows. For the conservation of Rothkos Harvard room, it is brought into context within his other commissions and environments. The original color of the works is determined by the digital restoration of contemporary photographs. With a camera projector system a compensation image is calculated that is projected onto the original canvas resulting in a restored color appearance. This approach of inpainting with light is compared with considerations of cleaning and inpainting in conventional conservation treatments. Overall lighting and architecture including the unusual wall color carefully chosen by Rothko play a key role in the treatment of the Mural cycle as an environment.

An analytical approach to detect non-original embellishments on Classic Mimbres vessels

Abstract Native American Indian Mimbres vessels from the Classic period (AD 1000–1150) are known for their geometric and figurative black designs on a white background. Owing to the growing popularity of Classic Mimbres vessels among collectors, it is believed that a large number of authentic Mimbres vessels have had their original designs embellished to increase their market value. Typically, the embellishments will enhance a simple central design of an authentic Classic Mimbres vessel to a more complex figurative design. A study was carried out by the Harvard Art Museums, in collaboration with the Harvard Peabody Museum of Archaeology and Ethnology, to investigate the composition of the black, red, and polychrome designs using pyrolysis-gas chromatography-mass spectrometry. Seven of the 25 vessels examined contained critical passages executed in synthetic modern paint media, indicative of deceptive embellishments.

Painted textiles: knowledge and technology in the Andes

Many Andean textiles are painted, a tradition practiced across the Andes as early as the Lithic period (ca. 10000‒4000 B.C.E). Despite its prevalence and aesthetics, research into painted textile technology is limited. Recently, samples from nine painted Andean textiles were collected from different museums and analyzed at the Getty Conservation Institute in Los Angeles. The samples represent a range of cultures, locations, and times. Analytical techniques included polarized light microscopy and X-ray florescence spectroscopy. Due to the paucity of published data on painted textiles, a comparison is made with mural paintings. Results show that Andean painters used a range of pigments, including ocher and cinnabar, and that pigments were chosen based on their chemical and physical characteristics from at least the Early Horizon period (ca. 950 B.C.E.‒200 C.E.) onward, although there were also cultural preferences for specific pigments. The quality of the cinnabar pigment especially shows that Andean painters had great technical knowledge and skills, superior to what was previously suspected. Patterns of pigment choice and application indicate that painted textiles were primarily produced for funerary purposes.