This study is the first systematic survey of a large corpus of zinc white (ZnO) artists’ materials. Zinc white is a white pigment developed within the wave of 19th-century technological developments ...in the paint industry. The composition, particle morphology and size, and luminescence of 49 zinc white samples from artists’ materials were characterized, including three references of known synthesis methods (indirect and direct) and synthesized by the authors (ZnO nanosmoke). The corpus included historical and modern zinc white pigment powders and paint materials from the leading European and American color manufacturers. The study aims to characterize and evaluate the variability of the properties of zinc white and its paint formulations. The reference materials presented properties in agreement with the literature: indirect ZnO exhibited submicron prismoidal blue-luminescent particles of higher purity than direct ZnO, which had larger acicular green-luminescent particles. ZnO nanosmoke presented acicular (tetrapod-like) blue/green-luminescent nanoparticles. Composition, particle morphology, size, and documentary sources suggested a production via the indirect method for the analyzed corpus. However, the luminescence behavior was more complex to interpret. The fundamental emission of ZnO was not always detected, even in pure ZnO powders. Three trends were identified: smaller ZnO particles for the most recent samples; green luminescence connected to larger particle size; fewer trace elements, and of the same type (i.e., lead, sulfur) for historical materials. Another interesting finding was the detection of hydrozincite in some powders, likely a degradation product of ZnO. In terms of methodology, cathodoluminescence proved a valuable tool for pigment identification. The study provides a database of zinc white references for pigment and artwork analysis.
This research paper presents a novel methodology for determining the burn temperature of archaeological bones using electron paramagnetic resonance (EPR) supported by Fourier Transform Infrared ...(FTIR) spectroscopy. A selection of bone samples, burned at different temperatures, were examined with EPR. The EPR spectra displayed dependency on burn temperature, showing characteristic narrow spectra of carbon radicals, Mn
2
+
signals and signals from different carbonate ions. This methodology was applied to selected archaeological samples of burnt bones, successfully determining the burn temperature these bones were exposed to in the past. The extracted burn temperatures showed good agreement with those determined from a complementary reflectance FTIR study.
Since the introduction of the Oddy test in 1973, many museums and cultural institutions have put the method in use, developing their own versions and protocols. Currently the 3-in-1 version, ...temperature at 60 ºC and 2 g of tested material are set as common practice; however, other variables of the test are not standardized. The purpose of this study is to examine current versions of the Oddy test, to identify differences in the results derived from variations in the procedures, and ultimately raising awareness within the conservation community to work together towards a standardized protocol. In this article, we review the available information on the methodological differences in Oddy test protocols published in the literature related to glassware cleaning, coupon preparation, reaction vessel setup and rating of materials. Based on the review, and to highlight the many variables that could affect the results of the test, seven European cultural institutions working under the H2020 IPERION HS project performed a comparative 3-in-1 Oddy test by blindly evaluating the same ten materials. Each institution used its own test methodology but some guidelines were advised: (1) Detergents as a cleaning procedure for glassware, (2) P600 sandpaper or micromesh pad close to 1500 to prepare metal coupons and (3) 1:100 as water–air ratio. Despite this, differences between institutions’ results were still observed. Some of them are due to the differences in the coupons preparation, either in the sanding pattern or in the edge area. In order to separate the contribution of the experimental setup and the subjectivity of the evaluation in the discrepancies, coupons from all institutions have been rated by a single team of judges with experience in the Oddy Test. Results show that differences in the evaluation criteria play a relevant role in the discrepancies of the results, especially for institutions with less experience in the test. These results highlight the need to further standardize the methodology and criteria for visual assessment. Nevertheless, the Oddy test has been found to be reliable for the identification of materials that produce emissions hazardous for the conservation of cultural assets.
This work presents an assessment of the different decoration techniques applied in the two glass windows from the Casa-Museu Dr. Anastácio Gonçalves (Lisbon, Portugal) by Optical coherence tomography ...(OCT). The Dining Room glass window was found to be decorated with grisailles and acid etching, and the
Atelier
window with grisaille, enamel, and cold painting. The alteration state of the surface decorations was also assessed. The thicker surface decorations (grisailles and enamels) presented cracks and detachments, in contrast to the thinner lines which are normally well preserved. OCT is a suitable technique for characterizing glass decoration in situ without dismounting the stained-glass window; and able to reveal the condition and methods of manufacture that cannot be detected simply by visual inspection.
Literature research revealed that scientific work on the characteristics of historical decorative laminates (DLs), like typology, and particularly the material-technical aspects related to the ...composition and build-up is scarce in the field of conservation-restoration of modern materials. This paper aims to take the first step towards filling in this knowledge gap by demonstrating that an in-depth literature research and complementary chemical-physical analytical techniques are useful in characterising and contextualising historic decorative laminates. This research focused on gaining additional information within chemical analyses on material-technical insights. This could serve as a basis for a more comprehensive historical context. Several historical samples from different sample-catalogues and museum objects, spanning a period from 1953 to 1993, were collected and their respective cross-sections were characterised with infrared (mapping), FT-Raman, and dispersive micro-Raman spectroscopy. The different layers, such as the protective, decorative, and core layers were investigated, and materials such as melamine formaldehyde, urea formaldehyde, cellulose, lignin, titanium dioxide (rutile), zinc sulphide, synthetic organic pigments PR112 (monoazo pigment, Naphthol AS), and PG8 (azo metal complex, Pigment Green B) were detected.
Graphical Abstract
The impacts of climate change on heritage collections in Mediterranean museums are serious and lead to accelerated material degradation, loss of value, increasing conservation costs and ...climatisation. Climate change scenarios and simulation models have been developed to predict the extreme and average future environmental conditions and to assess the future long-term risks caused by global warming for museum buildings and their collections in Mediterranean countries, with Egypt being particularly at risk. This paper presents the results of the risk analysis of the indoor and outdoor environments in Alexandria Museum of Fine Arts (AMFA) in Egypt to provide an overview of the current situation of conservation and museum management and to provide evidence-based data to support decision-making regarding preventive conservation given the museum's limited funding, capacity and resources. Unfortunately, the air quality in the museum cannot be considered satisfactory and specific measures need to be taken to improve the level of air quality and museum and building management. The results enabled an assessment of indoor air quality and provided information on potential risks to the museum building and collections, including variations in temperature (T) and relative humidity (RH), concentrations of NO
2
, SO
2
, O
3
, CO
2
, acetic and formic acid and lighting conditions, as well as the location and management of the museum. The results necessitate the development of a preventive conservation plan to address the challenges associated with high T/RH fluctuations and pollution pressure. This requires more regular use of the HVAC system within certain T/RH set points as well as minimising light exposure and the use of UV-filtering glazing. Care should be taken to ensure that housekeeping and emergency preparedness reduce the damping and salt florescence in the museum building. However, dealing with the impact of climate change on indoor and outdoor environments and museum collections in Mediterranean museums requires a holistic and adaptive approach that includes joint collaboration, research, training and strategic planning to ensure the long-term preservation of valuable cultural heritage collections in different climates with customised adaptations based on local environmental conditions, resources and needs. Resilience planning should be region-specific and take into account the potential impacts of extreme weather events, sea level rise and other climate-related challenges.
Grisaille was the first paint applied on stained-glass panels, used in Europe since the twelfth century. Historical written sources described the use of iron and copper together with a high ...lead-silica base glass in the grisailles production. This project aims to study the evolution of the grisaille paint composition throughout time and the changes in the raw materials used in their production using non-destructive and non-invasive techniques. To achieve this objective, 23 grisaille samples dated from the 13th to the twentieth centuries from nine different countries (Portugal, Poland, United Kingdom, Sweden, Norway, Belgium, Low Countries, Germany, and France) were studied by means of micro particle-induced X-ray emission (μ-PIXE), micro energy dispersive X-ray fluorescence (μ-EDXRF), laser-induced breakdown spectroscopy (LIBS), laser-induced fluorescence (LIF), non-linear optical microscopy (NLOM) in the modality of multiphoton excitation fluorescence (MPEF) and optical microscopy (OM). The results showed that it was possible to identify compositional differences and patterns throughout the samples when compared with literature results. The preference for using copper in central and south-central European countries and the addition of new compounds (CoO, Cr
2
O
3
, MnO) as colouring agents since the nineteenth century was verified. The LIBS analyses allow the identification of boron on two samples, confirming the change of base glass components since the seventeenth century. The NLOM-MPEF showed the capability of this technique to measure the grisaille paint layers’ thickness. This non-invasive multi-analytical and complementary approach proves itself efficient in identifying changes in the grisaille’s composition throughout time, which can be interpreted as changes in the raw materials and manufacture used in the production of these paint materials.
