Macroscale multimodal imaging reveals ancient painting production technology and the vogue in Greco-Roman Egypt.

Macroscale multimodal chemical imaging combining hyperspectral diffuse reflectance (400-2500 nm), luminescence (400-1000 nm), and X-ray fluorescence (XRF, 2 to 25 keV) data, is uniquely equipped for noninvasive characterization of heterogeneous complex systems such as paintings. Here we present the first application of multimodal chemical imaging to analyze the production technology of an 1,800-year-old painting and one of the oldest surviving encaustic ("burned in") paintings in the world. Co-registration of the data cubes from these three hyperspectral imaging modalities enabled the comparison of reflectance, luminescence, and XRF spectra at each pixel in the image for the entire painting. By comparing the molecular and elemental spectral signatures at each pixel, this fusion of the data allowed for a more thorough identification and mapping of the painting's constituent organic and inorganic materials, revealing key information on the selection of raw materials, production sequence and the fashion aesthetics and chemical arts practiced in Egypt in the second century AD

Characterization of Maltese pottery of the Late Neolithic, Bronze Age and Punic Period by neutron activation analysis

A set of 41 samples from Tas-Silg, Malta, has been analysed by neutron activation. It contained nine ware groups formed by visual examination covering the Late Neolithic, Bronze Age and Punic Periods (c. 3000–218 BC). Despite this diversity and long time range, seven of these ware groups, including the ‘Thermi Ware’, all have a similar chemical composition and, therefore, have been made from the same clay. This points most probably to a local origin. One group from the Punic Period, containing only Bricky Red cooking ware, is chemically separate and represents a second distinct pattern probably assignable to a local production. Five amphora sherds also from the Punic Period, and consisting of a micaceous fabric, all have different chemical characteristics and are probably imports from overseas production sites of unknown location.peer-reviewe

Degrado e problematiche conservative di un dipinto ad olio su pietra a Malta

This article provides a sumtnary of the diagnostic study undertaken on an oil-based painting on a dome of a church in Malta. Painted in 1903 and extensively restored in 1963, this mural is now found to be in an appalling condition. To investigate causes and processes of deterioration, a multidisciplinary approach was followed. This included historical research, non-invasive examination, sampling and analysis, and environmental monitoring. Soluble salts, mainly gypsum and minor amounts of halite, were found to be the main causes of deterioration. Salt crystallization cycles were triggered by recurrent and prolonged rainwater infiltrations, whilst solar radiation may have played a role by increasing the number of crystallization cycles. Deterioration was also favoured by intrinsic factors. Oil-based paintings applied to porous materials, in this case a very porous limestone, create a barrier to the passage of water, and favour the formation of an interface between the wall and the paint layer, under which salts may crystallize. In this case, the artist applied his painted strata over pre-existing paint layers making the painting's structure even more prone to delamination. The limestone over which the painting was applied was found of bad quality and susceptible to salt decay. The difficult issues in relation to the preservation of this painting are referred to and are open for discussion.peer-reviewe

Acquisition of High Spectral Resolution Diffuse Reflectance Image Cubes (350–2500 nm) from Archaeological Wall Paintings and Other Immovable Heritage Using a Field-Deployable Spatial Scanning Reflectance Spectrometry Hyperspectral System

There is growing interest in bringing non-invasive laboratory-based analytical imaging tools to field sites to study wall paintings in order to collect molecular information on the macroscale. Analytical imaging tools, such as reflectance imaging spectrometry, have provided a wealth of information about artist materials and working methods, as well as painting conditions. Currently, scientific analyses of wall paintings have been limited to point-measurement techniques such as reflectance spectroscopy (near-ultraviolet, visible, near-infrared, and mid-infrared), X-ray fluorescence, and Raman spectroscopy. Macroscale data collection methods have been limited to multispectral imaging in reflectance and luminescence modes, which lacks sufficient spectral bands to allow for the mapping and identification of artist materials of interest. The development of laboratory-based reflectance and elemental imaging spectrometers and scanning systems has sparked interest in developing truly portable versions, which can be brought to field sites to study wall paintings where there is insufficient space or electrical power for laboratory instruments. This paper presents the design and testing of a simple hyperspectral system consisting of a 2D spatial spot scanning spectrometer, which provides high spectral resolution diffuse reflectance spectra from 350 to 2500 nm with high signal to noise and moderate spatial resolution (few mm). This spectral range at high spectral resolution was found to provide robust chemical specificity sufficient to identify and map many artists’ materials, as well as the byproducts of weathering and conservation coatings across the surface of ancient and Byzantine Cypriot wall paintings. Here, we present a detailed description of the hyperspectral system, its performance, and examples of its use to study wall paintings from Roman tombs in Cyprus. The spectral/spatial image processing workflow to make maps of pigments and constituent painting materials is also discussed. This type of configurable hyperspectral system and the imaging processing workflow offer a new tool for the field study of wall paintings and other immovable heritage

Macroscale multimodal imaging reveals ancient painting production technology and the vogue in Greco-Roman Egypt.

Macroscale multimodal chemical imaging combining hyperspectral diffuse reflectance (400-2500 nm), luminescence (400-1000 nm), and X-ray fluorescence (XRF, 2 to 25 keV) data, is uniquely equipped for noninvasive characterization of heterogeneous complex systems such as paintings. Here we present the first application of multimodal chemical imaging to analyze the production technology of an 1,800-year-old painting and one of the oldest surviving encaustic ("burned in") paintings in the world. Co-registration of the data cubes from these three hyperspectral imaging modalities enabled the comparison of reflectance, luminescence, and XRF spectra at each pixel in the image for the entire painting. By comparing the molecular and elemental spectral signatures at each pixel, this fusion of the data allowed for a more thorough identification and mapping of the painting's constituent organic and inorganic materials, revealing key information on the selection of raw materials, production sequence and the fashion aesthetics and chemical arts practiced in Egypt in the second century AD

Chemical Characterization and Molecular Dynamics Simulations of Bufotenine by Surface-Enhanced Raman Scattering (SERS) and Density Functional Theory (DFT)

7 pags., 4 figs., 1 tab.Bufotenine (5-hydroxy-N,N-dimethyltryptamine) is a natural tryptamine derivative with hallucinogenic activity. In this paper, we present novel chemical and molecular conformational analyses of bufotenine based on an experimental and theoretical approach integrating surface-enhanced Raman scattering (SERS) and density functional theory (DFT). For the first time, low concentrations of bufotenine in acetonitrile solutions were analyzed by SERS using two types of silver nanoparticle substrates synthesized via one- or two-step reduction processes. The vibrational characteristics of this molecule were verified by molecular dynamics simulations of Raman bands based on DFT. Here we demonstrate the potential of this integrated approach for the identification of bufotenine, a prominent hallucinogenic agent, establishing an innovative rapid and accurate sensing and characterization method of the identification of controlled substances at trace amounts.This work has been supported by the Spanish Ministerio de Ciencia e Innovación under the PID2020-113900RB-I00/AEI/10.13039/501100011033 project

Oil painting on stone : a case study on original technique and deterioration of an early 20th century painting by Giuseppe Calì in Malta

Maltese wall paintings from the Baroque period onwards were mostly executed in oil or oil-based media applied directly to local limestone (Globigerina Limestone), which is a soft, very porous stone (porosity ~ 40%). These murals are often found in a poor state of conservation. One such painting on a dome of a church located near Malta's main harbour was chosen as a case study. · Painted in 1903 and heavily restored in 1963, the painting's advanced state of deterioration makes it an excellent example to review/examine and understand the most common effects and processes of deterioration related to similar wall paintings, and thus to provide essential infonnation for establishing a proper conservation strategy.peer-reviewe