Abstract: Historical glass, especially medieval glass, can undergo weathering under the influence of time and environmental conditions. The aim of this investigation was to better understand the processes involved in this natural degradation process by studying artificially altered glass samples prepared for the use of evaluation of conservation methods. Non-durable glass sensors produced by the Fraunhofer Institute (type M1.0) were used as a starting material for artificial alteration. These were immersed in acidic (pH = 0, 2, 4) and neutral solutions (1 h – 8 h). In a second stage the glass samples were immersed in a 0.5 M MnCl2 solution (24 h, 48 h and 72 h), allowing intrusion of Mn from the solution into the gel layer. The samples were characterized at different stages with reflectance FTIR spectroscopy, mu XRF mapping and mu XANES. All measurements were carried out at ESRF, beamline ID21. Reflectance FTIR spectroscopy measurements were performed in the 800 4000 cm(-1) range. Cluster analysis of the resulting maps evidenced the rapid growth of the gel layer in strong acidic conditions. The average spectra for each cluster feature show for the original glass a strong Si-O- stretching band between 900 and 1000 cm(-1), whereas the gel layer could be identified by the increasing Si-O-Si bands around 1100 and 1250 cm(-1). mu XRF maps were recorded at different stages of the experiment at energies around the Mn-K edge (6.539 keV) and with a step size of 2 by 2 m. These confirm the leaching of K+ and Ca+2 from the glass and the intrusion of Mn from the solution. Mn was found throughout the entire gel layer, but with a concentration gradient peaking at the surface. XANES point measurements were recorded at various points where Mn was present. No spatial variation was found, but linear combination fitting of the spectra with various Mn reference compounds indicated that Mn2+Mn23+O4 is the main Mn compound in the gel layer, as was hypothesised by Watkinson et al. The standard corroded glass samples studied here can be used for the evaluation of conservation treatments in follow-up experiments. (C) 2013 The Authors. Published by Elsevier B.V. Selection and peer-review under responsibility of the IA-CS (Italian Association of Conservation Scientists) and University of Antwerp

Abstract: A hitherto unknown composition is highlighted in the red and black inks preserved on ancient Egyptian papyri from the Roman period (circa 100 to 200 CE). Synchrotron-based macro-X-ray fluo-rescence (XRF) mapping brings to light the presence of iron (Fe) and lead (Pb) compounds in the majority of the red inks inscribed on 12 papyrus fragments from the Tebtunis temple library. The iron-based compounds in the inks can be assigned to ocher, notably due to the colocalization of Fe with aluminum, and the detection of hematite (Fe2O3) by micro-X-ray diffraction. Using the same techniques together with micro-Fourier transform infrared spectroscopy, Pb is shown to be associated with fatty acid phosphate, sulfate, chloride, and carboxylate ions. Moreover, microXRF maps reveal a peculiar distribution and colocalization of Pb, phosphorus (P), and sulfur (S), which are present at the micrometric scale resembling diffused “coffee rings” surrounding the ocher particles imbedded in the red letters, and at the submicrometric scale concentrated in the papyrus cell walls. A similar Pb, P, and S composition was found in three black inks, suggesting that the same lead components were employed in the manufacture of carbon-based inks. Bearing in mind that pigments such as red lead (Pb3O4) and lead white (hydrocerussite [Pb-3(CO3)(2)(OH)(2)] and/or cerussite [PbCO3]) were not detected, the results presented here suggest that the lead compound in the ink was used as a drier rather than as a pigment. Accordingly, the study calls for a reassessment of the composition of lead-based components in ancient Mediterranean pigments.

Abstract: An extended set of 18th century glass vessels was analyzed by means of SEM-EDX (major and minor element composition) The fragmented archaeological objects were recovered from a latrine belonging to the early 18th century building phase of the nunnery of Clairefontaine, near Arlon (B). On the basis of typology and decoration, the major part of the vessels could be dated around the middle of the 18th century. Variety in color and weathering of the glass suggest differences in glassmaking recipes and in the composition and origin of raw materials. The results of the analysis show how two main compositional groups constitute about 90% of the analyzed glass set, and these are constituted by potash glass (transparent beakers) and high lime low alkali glass (green bottles). Next to these, a few potash-lime and soda glasses are also found. The type of alteration has also a clear relation with the original glass composition.

Abstract: In this publication optical spectroscopy is considered to be a supplementary technique to study ancient colored glass. It results from a systematic study of the UV-VIS-NIR transmission spectra of intentionally colored glass fragments from various archaeological and historical sites and dated from the Roman period to the 21th century AD. The main goal consists of defining optical sensing parameters for this type of material. The considered colorants are iron, cobalt, manganese, copper and chromium. It is proved that many cases exist where optical spectroscopy can be seen as a straightforward, non-destructive, low-cost and in-situ applicable technique in identifying authentic material or to obtain information about the origin of the material. Possible sensing parameters are defined as the absence/presence of absorption bands characteristic for a specific coloring metal oxide and the spectral position of these bands. These parameters could reveal information about the applied furnace conditions and/or to the composition of the glass matrix. It is shown that the cobalt absorption band situated around 535 nm for soda rich glasses (Roman and industrial times) is shifted towards 526 nm for potash rich glasses (medieval and post-medieval times).

Abstract: Infrared artwork inspection is typically performed through active thermography and infrared reflectography (IRR) with different setups and cameras. While IRR is an established technique in the museum field, exploiting mainly the IR-A (0.7 – 1.4 mu m) band to probe for hidden layers and modifications within the paint stratigraphy system, active thermography operating in the IR-C range (3 -5 mu m) is less frequently employed with the aim to visualize structural defects and features deeper inside the build-up. In this work, we investigate the usability of an IR-B+C system to identify overpainted works of art below a relatively thick absorbing layer of lead white paint.

Abstract: The ongoing conservation treatment program of the Ghent Altarpiece by Hubert and Jan Van Eyck, one of the iconic paintings of the west, has revealed that the designs of the paintings were changed several times, first by the original artists, and then during later restorations. The central motif, The Lamb of God, representing Christ, plays an essential iconographic role, and its depiction is important. Because of the prevalence of lead white, it was not possible to visualize the Van Eycks' original underdrawing of the Lamb, their design changes, and the overpaint by later restorers with a single spectral imaging modality. However, by using elemental (x-ray fluorescence) and molecular (infrared reflectance) imaging spectroscopies, followed by analysis of the resulting data cubes, the necessary chemical contrast could be achieved. In this way, the two complementary modalities provided a more complete picture of the development and changes made to the Lamb.

Abstract: Over time, artist pigments are prone to degradation, which can decrease the readability of the artwork or notably change the artist's intention. In this article, the visual implication of secondary degradation products in a degraded yellow rose in a still life painting by A. Mignon is discussed as a case study. A multimodal combination of chemical and optical imaging techniques, including noninvasive macroscopic x-ray powder diffraction (MA-XRPD) and macroscopic x-ray fluorescence imaging, allowed us to gain a 3D understanding of the transformation of the original intended appearance of the rose into its current degraded state. MA-XRPD enabled us to precisely correlate in situ formed products with what is optically visible on the surface and demonstrated that the precipitated lead arsenates and arsenolite from the yellow pigment orpiment and the light-induced fading of an organic yellow lake irreversibly changed the artist's intentional light-shadow modeling.

Abstract: Radioactive particles originating from nuclear fuel reprocessing at the United Kingdom Atomic Energy Authority's Dounreay Facility were inadvertently released to the environment in the late 1950s to 1970s and have subsequently been found on site grounds and local beaches. Previous assessments of risk associated with encountering a particle have been based on conservative assumptions related to particle composition and speciation. To reduce uncertainties associated with environmental impact assessments from Dounreay particles, further characterization is relevant. Results of particles available for this study showed variation between Dounreay Fast Reactor (DFR) and Materials Test Reactor (MTR) particles, reflecting differences in fuel design, release scenarios, and subsequent environmental influence. Analyses of DFR particles showed they are small (100-300 mu m) and contain spatially correlated U and Nb. Molybdenum, part of the DFR fuel, was identified at atomic concentrations below 1%. Based on SR-based micrometer-scale X-ray Absorption Near Edge Structure spectroscopy (mu-XANES), U may be present as U (IV), and, based on a measured Nb/U atom ratio of similar to 2, stoichiometric considerations are commensurable with the presence of UNb2O7. The MTR particles were larger (740-2000 mu m) and contained U and Al inhomogeneously distributed. Neodymium (Nd) was identified in atomic concentrations of around 1-2%, suggesting it was part of the fuel design. The presence of U(IV) in MTR particles, as indicated by mu-XANES analysis, may be related to oxidation of particle surfaces, as could be expected due to corrosion of UAlx fuel particles in air. High U-235/U-238 atom ratios in individual DFR (3.2 +/- 0.8) and MTR (2.6 +/- 0.4) particles reflected the presence of highly enriched uranium. The DFR particles featured lower Cs-137 activity levels (2.00-9.58 kBq/particle) than the MTR (43.2-641 kBq Cs-137/particle) particles. The activities of the dose contributing radionuclides Sr-90/Y-90 were proportional to Cs-137 (Sr-90/Cs-137 activity ratio approximate to 0.8) and particle activities were roughly proportional to the size. Based on direct beta measurements, gamma spectrometry, and the VARSKIN6 model, contact dose rates were calculated to be approximately 74 mGy/h for the highest activity MTR particle, in agreement with previously published estimates. (C) 2020 The Authors. Published by Elsevier B.V.

Abstract: The chemical composition, as determined by electron probe X-ray microanalysis of a series of ca. 100 archaeological glass fragments, excavated at the Raversijde site (Belgium) is discussed. In the 15th-16th century, Raversijde was a flourishing fishermen town located on the shore of the North Sea, close to the city of Ostend. As a consequence of several battles that were fought in its vicinity, the site was abandoned in the 16th century and was not occupied since then. It is one of the rare archaeological sites in Europe that contains a significant amount of information on the daily life inside a small but affluent medieval community. A comparison of the chemical composition of fragments of vessels and window glass encountered in Raversijde to those found in urban centres in Belgium and to literature date on German and French archaeological finds shows that glass made with wood ash dominates. Usually, it concerns artifacts with a predominantly utilitarian use. A few objects made with sodic (i.e., Na-rich) glass were also encountered, likely to have been imported from Venice during the 15th century or in later periods from an urban centre such as Antwerp, where Facon-de-Venice glass manufacturing activities were established near the start of the 16th century. (C) 2004 Elsevier B.V. All rights reserved.