ABSTRACT With the continuous rise in global temperatures and the concurrent increase in atmospheric CO₂ concentration, the deterioration of immovable cultural heritage under climate change has attracted growing scholarly attention. This study systematically investigates the weathering mechanisms of limestone and marble, two representative carbonate stones, under conditions simulating elevated CO₂ environments, the principal contributor to the greenhouse effect. Laboratory-based accelerated simulation experiments were conducted, integrating ultra depth of field microscope (UDFM), polarized optical microscopy (POM), x-ray diffraction analysis (XRD), high-definition camera (HDC), electronic balance (EB), scanning electron microscopy (SEM), inductively coupled plasma – atomic emission spectrometry (ICP-AES), and automated surface area and porosity analyzer (ASAP) analysis. Comparative analyses were performed on the microstructure, mineral composition, dissolution rate, and pore characteristics of rock samples before and after CO₂ exposure. The results demonstrate that CO₂ significantly accelerates the dissolution and deterioration of limestone and marble, independent of liquid water involvement. Under non-precipitation conditions, high-concentration CO₂ can adsorb onto rock surfaces and infiltrate the pore network through capillary condensation, inducing mineral dissolution – reprecipitation reactions of calcite and related phases. These reactions promote surface corrosion, granular detachment, and structural weakening. This study elucidates the intrinsic mechanism by which CO₂ intensifies the weathering of carbonate stone relics in greenhouse environments, providing both theoretical and experimental insights into their deterioration processes. The findings offer a scientific basis for the preventive conservation and environmental adaptability management of limestone and marble heritage materials.

ABSTRACT The Sanxingdui site, containing the world's largest Bronze Age ivory collection, provides critical insights into ancient Shu's trade networks and paleoenvironment. However, water loss in these waterlogged ivories causes structural damage through delamination and dentin degradation. In this study, we utilized X-ray computed tomography (X-CT) to non-destructively and dynamically monitor the water loss process of four ivories from the K7 sacrificial pit at Sanxingdui site under different temperatures and humidity (25°C and 50% RH; 5°C and 90% RH) and preservation methods (exposed, wrapped). Through three-dimensional model reconstruction and quantitative pore analysis, combined with the mechanical properties simulation of VG Studio Max software, the evolution of internal pore expansion and stress in ivory during the water loss process was revealed. The results show that the combination of low temperature and high humidity (5°C, 90% RH) when wrapped can significantly inhibit the evaporation rate of water (water loss rate <5%). Additionally, the pore structure is more stable, with the variation rates of peak von Mises equivalent stress, maximum shear stress and maximum principal stress at 103d reduced by about 31%, 36% and 166%, respectively, compared with those of the exposed group at 25°C and 50% RH. Correlation analysis further confirmed that the water loss rate was strongly and positively correlated with the porosity and the accumulation of each stress. This study established an X-CT-based multi-parameter evaluation system for ivory deterioration, which provided a theoretical foundation for implementing low-temperature, high-humidity wrapped conservation measures for waterlogged and deteriorated ivories unearthed from the Sanxingdui site.

ABSTRACT Physical in situ reconstruction has been one of the most contentious cultural heritage (CH) conservation techniques, yielding both positive and negative outcomes. Today, computer-based visualisation reconstruction is a well-established method for understanding, interpreting, presenting, promoting, and reconstructing the past. Several international heritage charters systematically discuss the potential of virtual reconstruction, demonstrating how robust 3D virtual reconstruction (3Dvr) can create a comprehensive repository. These charters establish practical guidelines and best practices in scientific virtual visualisation. Two notable examples are the London Charter (2009. For the Computer-Based Visualisation of CH, http://www.londoncharter.org) and the Seville Principles (2011. International Principles of Virtual Archaeology). This paper aims to illustrate the state-of-the-art development of concepts, practices, and related issues, spanning from physical reconstructions to 3Dvr, from the early stages to the present day. It illustrates the potential advantages of applying 3Dvr as a medium for promoting CH knowledge and tourism dissemination. It aims to provide a comprehensive overview of managing the rapid development and future of 3Dvr. Additionally, it discusses the various challenges and opportunities, focusing on ethical issues related to misleading and fake messages and trends in traditional, classical, and current fashions, as well as the 3Dvr of architectural and archaeological monuments. It clarifies and recommends that 3Dvr and physical in situ reconstruction should no longer be perceived as opposites; instead, they should be seen as a continuum that adds value to the creative communication of human experience and CH, provided it guarantees the principles of scientific research transparency, avoiding misleading and fake information and messages.

ABSTRACT The aim of this study is to determine the material characteristics of the paint layers and techniques of paintings executed in Late Roman and Byzantine churches located in the archaeological sites of Aigai, Olympos, and Anaia (Turkey) in order to select compatible materials prior to conservation treatments of the paintings and to establish the technical aspects of the paintings in relation to coeval Western examples. In this context, the execution technique, microchemical characteristics, stratigraphy of paintings, and mineralogical and chemical composition of the pigments were determined by polarized light microscopy (PLM), scanning electron microscopy coupled with X-ray energy dispersive spectroscopy (SEM-EDX), and Fourier transform infrared spectroscopy (FTIR). The analysis results indicated that wall paintings were executed by fresco, secco or fresco-secco techniques on a thin plaster layer that is composed of pure lime, straw, fine marble, brick, and sand aggregates. The ground layers of the paintings are composed of kaolin, calcite, and carbon black. The color compositions of the paintings were obtained by applying successive layers of paint on the ground layers. The pigments used in the paintings are mainly iron oxides for the red and yellow, green earth in celadonite and glauconite forms for greens, and lapis lazuli and Egyptian blue for blues. The present study demonstrates that the techniques and materials employed in the execution of wall paintings in Byzantine churches in Western Anatolia are analogous to those utilized in the Balkans, Crete, and Cyprus, with the exception of the presence of a clay-based ground.

ABSTRACT This study investigates suitable retouching systems for unvarnished acrylic dispersion paint films. The research, conducted in 2021 (phase 2), builds on and is compared with a study undertaken in 2007 by Shelly Sims (phase 1). In phase 1, conservators were surveyed to determine which materials they used to retouch unvarnished acrylic dispersion paintings. In phase 2, a different cohort of conservators was surveyed to ascertain which materials remain commonly used and whether options and opinions have changed since 2007. The retouching systems selected by Sims in 2007 informed by the phase 1 survey included Lascaux Aquacryl™ paints, Lascaux® Water Re-Soluble Medium, Aquazol® (50, 200, and 500), Golden MSA Conservation colours, Regalrez® 1094, and JunFunori®. The phase 2 study reviewed the same samples from the 2007 study, with the additions of Watercolours which were not available in 2007, in addition to Schmincke Gouache and Aquarell Watercolours, which broaden the study. The selected retouching systems in phase 2 were evaluated for handling and aesthetic properties on aged and damaged mock acrylic dispersion paintings. Solubility tests were also conducted on artificially and naturally aged samples from the 2007 study and on a range of newly prepared and light aged Watercolour samples to determine their long-term solvent-reversibility and ageing properties. Overall, watercolour, gouache, Aquazol®, and the Watercolours possessed the best aesthetic properties, offering close matches in colour, saturation, and gloss, with their reversibility and long-term ageing properties rendering them most suitable as retouching materials for use on acrylic dispersion paints.

ABSTRACT Although current restoration and conservation philosophy that interventions in the preserved condition of an artwork should be limited to the necessary minimum, in everyday practice conservators often encounter cases when they have to decide whether to remove some secondary paint layers. Therefore, it is essential to do a detailed examination to gain information about the individual layers of polychromy. In addition, the general criteria for making decisions about intervention need to be defined. This article suggests a rubric that the authors consider vital when deciding whether to remove or preserve polychrome layers on stone sculptures. The proposed criteria include conservation and restoration aspects, the evaluation of the context and authenticity and, in addition, aesthetic and visual aspects. Knowledge regarding the defined criteria increases during the examination (such as visual and microscopic examination, ultraviolet-induced visible fluorescence, hand-held X-ray fluorescence analysis, stratigraphic windows, and sampling for cross-section examination, FTIR, SEM, etc.). The decisive criteria application is described here using a practical example of the restoration of the Pensive Christ sculpture, a polychrome stone statue from the end of the eighteenth century from the treasury of the mediaeval cathedral of St. Barbara in Kutná Hora in the Czech Republic. Defining the criteria and awareness of limited knowledge about some of them during the individual examination stages contributed significantly to developing the discussion and making decisions about the restoration concept.

ABSTRACT A good storage system is crucial for the preservation of a museum's artefacts. The choice of these systems depends largely on the nature of the collection, in particular the materials and size of the artefacts, but also other external constraints such as the financial resources of the museum. Proper environmental monitoring and understanding how it impacts the conservation of materials are essential for implementing effective preventive conservation measures. This study examines the storage environment and the suitability of the storage systems of the National Museum of Science and Technology (MUNCYT) in Madrid (Spain) from the conservation point of view. For this purpose, metallic coupons were placed inside and outside a closed mobile shelving system and wrapped and unwrapped in a tissue used for large artefacts in an open pallet racking area. The corrosion of the coupons was evaluated in terms of corrosion rate by gravimetry and electrolytic cathodic reduction according to ISO 11844:2020, colour changes were analysed with a spectrophotometer, and the corrosion products formed were characterised by XRD in grazing incidence mode. The results enabled a comparison of the corrosiveness in different areas, identification of possible sources of aggressive pollutants, and demonstrated the effectiveness of storing artefacts inside shelving and tissue wrapping in reducing metal degradation (especially silver) of the artefacts in the MUNCYT collection.

ABSTRACT Cultural heritage sites, including libraries where historical texts are available, are responsible to staff, research visitors, and the public for providing a safe and healthy work and educational experience. Identifying hazards inherent and acquired on collections, or in contaminated work areas and storage environments, has become more prevalent with the use of XRF analysis (for metals), knowledge of collector's notes, and records of conservation methods. However, this is only source identification data, that typically does not directly correlate to the potential health risk from specific work tasks and where routes of exposure exist. An occupational exposure assessment, conducted by a qualified health and safety professional, will determine actual risks during work tasks via personal sampling devices and media, surface and dermal wipes, and other methods. An exposure assessment case study is presented, related to the testing and assessment of worker exposure to and workspace contamination from selected metals (arsenic, chromium, lead, and mercury) within historical collections at a regional library. Personal sampling results quantified potential inhalation exposures, wipe samples verified the presence of contaminants on hands (potential ingestion risk), and surface wipe results identified cross-contamination in collection storage and work areas. Detailed recommendations for improved safe work practices, personal protection, and other controls were offered. Understanding hazard sources, routes of exposure, and surface transference defines both the potential health risk and the methods to best control that exposure. Safety and collection preservation and conservation are not disjointed topics. Safety can work hand in hand to support the protection of collections.

ABSTRACT The Charles Deering McCormick Library of Special Collections at Northwestern University Libraries holds a significant collection of original materials on the Siege and Commune of Paris (ca. 1870-1871) including over 1,000 printed posters. 262 of these posters were printed on colored papers, which present unique material challenges for their preservation. By the 1860s, synthetic dyes and pigments nearly replaced natural colorants historically used in paper production as they were thought to be vastly superior in vibrancy and ease of use. Some synthetic pigments used in the late nineteenth century contain heavy metals such as lead, chromium, and mercury, adding health and safety concerns to treatment and housing considerations. Twenty-eight colored posters from the collection were examined using optical microscopy and X-ray fluorescence spectroscopy (XRF) to investigate their elemental profiles, while five of the 28 posters underwent further examination using polarized light microscopy (PLM) and Raman spectroscopy to identify suspected heavy metal pigments. XRF confirmed the elemental presence of lead and chromium in orange, yellow, green, and peach posters, and Raman analysis identified the pigment chrome yellow in the yellow and green posters. The results obtained were used to inform treatment and housing protocols alongside established institutional guidelines to reduce health and safety risks and address physical condition issues.