Restorer Research Articles

A Multi-Analytical Approach to Infer Mineral–Microbial Interactions Applied to Petroglyph Sites in the Negev Desert of Israel

Petroglyph sites exist all over the world. They are one of the earliest forms of mankind’s expression and a precursor to art. Despite their outstanding value, comprehensive research on conservation and preservation of rock art is minimal, especially as related to biodeterioration. For this reason, the main objective of this study was to explore the factors involved in the degradation of petroglyph sites in the Negev desert of Israel, with a focus on biodegradation processes. Through the use of culture-independent microbiological methods (metagenomics), we characterized the microbiomes of the samples, finding they were dominated by bacterial communities, in particular taxa of Actinobacteria and Cyanobacteria, with resistance to radiation and desiccation. By means of XRF and Raman spectroscopies, we defined the composition of the stone (calcite and quartz) and the dark crust (clay minerals with Mn and Fe oxides), unveiling the presence of carotenoids, indicative of biological colonization. Optical microscopy and SEM–EDX analyses on thin sections highlighted patterns of weathering, possibly connected to the presence of biodeteriorative microorganisms that leach the calcareous matrix from the bedrock and mobilize metal cations from the black varnish for metabolic processes, slowly weathering it.

How is the quality of the available evidence on molar-incisor hypomineralization treatment? An overview of systematic reviews.

This overview analyzed the quality of the systematic reviews (SRs) available on treatments for molar-incisor hypomineralization (MIH). Six electronic databases were searched (PubMed/MEDLINE, Scopus, Web of Science, LILACS, Brazilian Bibliography of Dentistry and Cochrane Library) until March 2022. Two reviewers independently performed the selection, the quality assessment (Assessment of Multiple Systematic Reviews 2 - AMSTAR-2), and the risk of bias assessment of the SR (Risk of Bias in Systematic Reviews - ROBIS). Two hundred nine records were retrieved; after removing duplicates and applying the inclusion/exclusion criteria, 5 SRs remained. Three SRs were rated as showing critically low methodological quality and high risk of bias, and two were rated as moderate methodological quality and low risk of bias. The identified treatments that may be suitable for MIH were classified as (1) non-invasive - casein incorporated into toothpaste and sugar-free chewing gum, toothpaste containing arginine, 0.4% stannous fluoride gel; fluoride varnish; (2) micro-invasive - resin sealants for pits and fissures, microabrasion, dental whitening, resin infiltration; (3) invasive - ART restorations, indirect restorations (metal, composite, or ceramic); and (4) mixed intervention - stainless steel crowns. Despite the considerable number of published papers included in this set of systematic reviews, the evidence supporting the effectiveness of treatments for treating MIH is limited due to the methodological quality and risk of bias of the systematic reviews, as well as the quality of the primary studies (PROSPERO: CRD42020144831). Different treatments have been purposed for MIH treatment, but there is still not enough scientific evidence of good quality for the establishment of a definitive clinical protocol for the treatment of MIH.

Fracture Resistance of Root-Canal Treated Premolars Restored with Dentin Replacement Materials: An In-vitro Study.

Conservative restorations of endodontically treated premolars have yielded mixed results. The present study aimed to compare fracture resistance of endodontically treated premolars with Class II mesial-occlusal cavity preparations, restored with either Smart Dentin Replacement (SDR; Dentsply Sirona) material, Biodentine (Septodont) or ceramic inlays. Thirty-two extracted premolars were randomly divided into four equal groups (n = 8): Group 1 served as a control group with teeth left intact; teeth in the remaining three groups received root canal treatment followed by a mesio-occlusal cavity preparation. These crowns were restored with: Biodentine in group 2, SDR in group 3 and ceramic inlays in group 4. A computer-controlled Instron universal testing machine subjected all specimens to compressive load until failure. Force at failure and fracture mode (above or below the cementoenamel junction) were recorded. The data were analysed using Fisher's exact test and one-way ANOVA followed by the post-hoc Tukey's test. Statistical significance was set at p < 0.05. The lowest mean load at failure was recorded for the inlay group. Loads at failure were statistically significantly higher for teeth restored with Biodentine than with SDR (p = 0.012) and ceramic inlays (p = 0.007). There were no statistically significant differences between the groups in terms of fracture mode (p = 0.440). Endodontically treated premolars with mesial-occlusal cavity preparation restored with Biodentine were more resistant to fracture than those restored with either SDR or ceramic inlays. Biodentine may prove a promising material to restore endodontically treated teeth with one missing proximal wall.

Javanese art conservation in Indonesia inheriting potentials of local wisdom through Wayang Wong Bocah

ABSTRACT The research focused on analyzing Javanese arts conservation by employing inheritance strategies of Wayang Wong Bocah. The research method comprised the following steps: data collection, data validation, and data analysis. The data were collected by observation, interview, and documentation. Moreover, the data were validated by source triangulation technique and analyzed by techniques as follows: data description, data screening, data interpretation, and evaluation. The data analysis relied on Hardsley’s theory regarding individual strategies in overcoming challenges and adapting to patterns of cultural changes. The results discovered that the conservation process of Wayang Wong Bocah performed by Tjipta Boedaja dance studio is regarded as: (1) an effort to preserve the culture by maintaining, protecting, conserving, and preventing it from damage and extinction; (2) an inheritance strategy by conducting routine training session to the children. In particular, the main findings of this study elaborate that the conservation and inheritance of Wayang Wong Bocah as the local wisdom potential require the passionate and willing individuals to conserve the art by ensuring the involvement of young generations as future art performers, the community as the support system of art conservation, and the government as the policymaker.

Change Comes from Within: Shared Efforts in Developing Conservation in Indonesia

ABSTRACT The field of cultural materials conservation in Indonesia faces various challenges pertinent to developing countries. As some of Indonesia’s emerging conservators, the authors identified that the first best step towards responding to these issues is through two-way learning and collaboration. Through the generous support of the Australia Awards in Indonesia’s Alumni Grant Scheme, the Bali Art and Heritage Conservation Internship Programme (BAHCIP) was conceived in 2020 and carried out in 2021 to act as a collaborative pilot project involving both local practitioners and international experts. At its core, BAHCIP is designed to introduce the conservation profession to cultural heritage workers and volunteers, facilitate knowledge exchange between practitioners, initiate critical and thought-provoking discussions, and most importantly, encourage the interns to pursue formal conservation studies. The main participants in this small-scale programme were recent graduates and emerging conservators as mentors, two local museums in Bali as hosts, and five interns of varying backgrounds. Given Covid-19 restrictions, the programme was delivered through a hybrid setting which involved an online lecture series and a three-week in-person internship. This paper presents an overview of the programme, discusses the unique conservation landscape in Indonesia and reports on how the pilot project might offer an effective and impactful pathway to the development of conservation in the country. The result, in general, indicates that BAHCIP has improved the interns’ understanding and awareness of the importance of conservation, enriched their conservation experience, and encouraged them to pursue conservation studies.

Following the Light: Use of Multimodal Imaging and Fiber Optic Spectroscopy to Evaluate Aging in Daylight Fluorescent Artists’ Pigments

Daylight fluorescent artists’ colors have been well established as fugitive. Upon exposure to light, these vibrant colors can fade and exhibit color shifts. Artwork containing these fluorescent colorants presents complex challenges for art conservators faced with conserving these inherently problematic materials. This paper examined nine fluorescent colorants obtained from Kremer Pigmente, referred to the previous literature and research, and attempted to quantify the visual and photographic observations of fading and color changes. It provides additional information that could be useful in considering conservation documentation and treatment. Fiber optic spectroscopy using ultraviolet and visible light sources was used to measure the spectral shifts of the colorants before and after exposure to light. The fluorescent colors exhibited alterations in intensity coupled with primary peak shifts in the spectrum corresponding to the optical fading and color shifts. Multimodal imaging was executed to analyze the pigments in different regions of the spectrum before and after aging, which has not been documented before with these fluorescent colorants. Imaging in various regions of the spectrum indicated differences in absorption and reflectance between the pigments as captured by a modified camera. The results were compared to recently published research including the identification of the dyes present in the Kremer line of pigments. Multimodal imaging and fiber optic spectroscopy provided valuable information for future documentation and conservation of artworks containing these colorants. Specifically, these non-invasive techniques provide a method to document and identify the spectral changes between the aged and unaged pigment, graph and predict the direction of overall color change, and provide useful data for establishing future conservation treatment protocols.

Research and Application of Color of Qiuci Murals Based on Intelligent Digital Image Processing Technology

In order to improve the color research effect of Qiuci murals, this paper combines digital technology, applies intelligent digital image processing technology to the color research of Qiuci murals, and builds an intelligent system. Moreover, this paper analyzes the color mural pixel digitization of murals from the perspective of digitization and conducts research from a microscopic perspective. In addition, in this paper, the expansion operation is performed for particularly small cracks, and the extraction area of the crack is correspondingly increased, which reduces the bad influence on the subsequent repair due to incomplete crack extraction. Finally, this paper constructs an intelligent mural analysis system based on the improved algorithm. The experimental research results show that the color research system of Qiuci murals based on intelligent digital image processing technology proposed in this paper has good effects and can play an important role in the digital protection and digital restoration of art.

The Conservation of Murals – A New Trend in Protecting Works of Art

In recent years, a trend has emerged in the field of art conservation, the aim of which is to protect street art objects. Attempts to conserve murals face many problems. This is due to various factors – lack of time distance to this type of objects, difficulties in assessing their artistic value, frequent lack of interest of artists in the conservation of their works, material impermanence of murals, their often-occasional nature; also, the fact that most of these objects are not legally protected. The paper discusses the problems faced by an art restorer who wants to save murals. Examples of murals are presented, the conservation of which is not possible, among others, due to the fact that the houses on which they were painted are intended for demolition. There are also examples of murals whose rescue from destruction gained public approval and the conservation of which was carried out. The paintings are in a very poor condition. This is a feature of most murals, which are usually made on old, unrepaired plasters with low-quality paints. Their maintenance is a very difficult task. The presentation shows the various stages of conservation of works lacated in Warsow. The conservation of the murals is carried out in order to preserve street art facilities. Apart from the involvement of art conservators, social support for this type of activity is also important. However, one should be aware that most of murals have no chance of becoming a permanent part of the city landscape. Their fate will be determined by chance.

Cryopreservation of Holm Oak Embryogenic Cultures for Long-Term Conservation and Assessment of Polyploid Stability.

Holm oak populations are severely affected by oak decline syndrome, and reliable methods of conserving the plant material are required. A vitrification-based cryopreservation method was used for the first time for the long-term conservation of holm oak embryogenic cultures. Successful cryopreservation was achieved after determining the best developmental stage of the somatic embryos used and the optimal incubation period in plant vitrification solution 2 (PVS2). Embryos were recovered from individual nodular embryogenic structures (NES) derived from four embryogenic lines after preculture on a medium containing 0.3 M sucrose, incubation in PVS2 vitrification solution for 15 min at 25 °C and direct immersion in liquid nitrogen (LN). Embryo recovery rates of 16.7–63.3% were obtained after cryostorage for four years in LN. In addition to the embryo developmental stage and the PVS2 treatment time, the genotype can also significantly affect embryo recovery after LN storage. There were no significant differences in plant regeneration or polyploid stability between somatic embryos and plants derived from control embryos (not cryopreserved) and cryopreserved embryos. The findings indicate that embryo proliferation, plant conversion and polyploid stability are maintained in material recovered from the vitrification solution and subsequently cryopreserved.

Preliminary Research into Education for Sustainability in Cultural Heritage Conservation

ABSTRACT Researchers and practitioners of cultural heritage conservation are increasingly aware of the field’s impact on the physical and social environment. Faculty at the UCLA/Getty Program in the Conservation of Cultural Heritage are working to support the next generation of researchers and practitioners to become leaders in adapting conservation for the climate crisis and addressing social inequity. This paper presents the first stage of an initiative to develop models for embedding sustainable practices into conservation education and producing scalable curricula for broad dissemination. In this first phase, we performed literature reviews, canvassed the field through surveys, conducted interviews and developed curricula for our laboratories and classrooms. Survey results indicate a high international interest in incorporating sustainability principles in cultural heritage education, but with a corollary challenge of being unable to substitute new concepts for those already taught. Literature reviews and interviews introduced the authors to existing pedagogical approaches for embedding sustainability within our courses. Sustainability concepts such as the Three Pillars of Sustainability, the United Nations Global Sustainable Development Goals (SDG) and the Inform, Engage, Empower and Embed (I3E) systems provide guidance in our teaching. The next phase of the initiative will involve a close evaluation of pedagogical systems for integrating sustainability into the existing curriculum to ensure that emerging professionals in art conservation, built heritage, libraries, archives, archaeology and historic preservation will prioritize intersectional environmentalism. A future goal is to disseminate educational models broadly for adaptation by others.

Matching and analysing conservation–restoration trajectories

The context of this work is an on-going project at the French National Library (BnF), which aims at providing predictions of the documents physical state based on their conservation–restoration histories. A document can be either in a good state and available to the readers, or damaged and unavailable to them. As libraries may contain millions of documents, the manual monitoring and analysis of their physical state is not realistic in practice. We therefore propose to analyse their conservation histories in order to derive reliable predictions of their physical state. To achieve this goal, we introduce in this paper the following contributions. First, we propose a representation of a document conservation history as a conservation–restoration trajectory, and we define its different types of events. We also propose a trajectory matching process that computes a similarity score between two conservation–restoration trajectories considering the terminological heterogeneity of the events, using an ontological model that represents the domain experts knowledge. Second, we provide a trajectory analysis process which identifies the most representative sequences of events of the deteriorated documents. Finally, we propose a prediction model for the physical state of the documents based on the trajectory analysis process. We present some experiments showing the effectiveness of the matching process as well as the prediction model.

The Practice of Data-Driven Journalism in Brazil: Between Disruption and the Reinstatement of Professional Values

This article presents an analysis of metadiscourses used by professionals and institutions that practice data-driven journalism (DDJ) in Brazil. It aims to understand how they define this practice and seek autonomy within the journalistic field. We conducted an argumentative analysis of editorial texts from 15 news outlets and carried out in-depth interviews with 33 professionals in the field, which allowed us to identify three prevalent metadiscourses: (1) cyberactivism; (2) reinforcing traditional journalistic values; and (3) authority. Using boundary-work as a theoretical basis for the analyses we discovered that all the discourses in these self-referential texts expressed some degree of disruption in DDJ, especially regarding data and its ability to reshape the concept of news transparency and introduce the values and practices of hacktivism in journalism. These discourses also reinforce elements of continuity and suggest a conservative restoration of production routines, values, and conventions in journalism without changing the basic ideology of the profession. Added to highlighting the flexibility and demarcation of this profession’s boundaries, this article also identifies the repertoires and identities mobilized in these processes that give Brazilian data journalism a higher profile.

Una reflexión teórica sobre la documentación del arte contemporáneo: una propuesta para un protocolo cronológico

Contemporary artwork is a complex entity made up of several superimposed planes: the material plane, the conceptual plane and the biographical plane. The need to apprehend the entity, determining where its substantial attributes lie, those that determine its consistency and constitute both, its essence and its specificity, is the objective of the documentation. This article proposes a documentation protocol that collects, from an empirical and useful perspective, the order in which the different actions of the contemporary art conservator should be documented. This protocol must analyse the different planes of which the artworks consist; it must apply an updated decision-making model and prioritise the relative importance of the material and immaterial constituents of the artworks. It must also include the documentation of the intervention process itself. The order and the tools to achieve it are analyzed in this article.

Process of Changes with Renewal/Loss of Tenement Houses in densely built-up areas of wooden buildings

Urban regeneration is key to restoring areas damaged by natural disasters. The research of Professor Toshiya Yamamoto, Department of Architecture, Meiji University, Japan, encompasses the promotion of the renovation of rows of houses called Nagaya, urban planning and transformation, housing reconstruction and regional revitalisation. His research is conducted in the urban area of Kyojima, Sumida Ward, Tokyo, which is a traditional Japanese living environment. A key concern in the restoration of Nagaya is ensuring that the buildings are as safe as possible so that the impact of earthquakes can be minimised. Another important element of the work is to promote a symbiotic relationship between residents and the community, with strong links between art projects and restoration. Yamamoto and the team's work will include performing analyses of the reconstruction project underway in the area of the Great East Japan Earthquake, analysing map data and the creation and categorisation of an original database constructed from building information and registration data. This data will then be repeatedly analysed in different relevant contexts. The goal of the research is to improve the structural understanding of recent urban transformation and evaluate the urban policies and plans that have strongly influenced it. The team also developed a manual for producing so-called 'evacuation maps'.

Morphoanotomical aspects of auxin herbicides-induced somatic embryogenesis in Euterpe edulis Martius, a symbol and threatened species of the Atlantic Forest

The palm Euterpe edulis presents primary meristematic growth without sprouting at the base, which prevents conventional vegetative propagation. Here, we assessed the effect of the herbicides 2,4-D and picloram on somatic embryogenesis as an alternative means for propagating and in vitro conservation of pro-embryogenic cultures of E. edulis, as their seeds are recalcitrant. Embryos could be effectively induced with 2,4-D (159.42 μmol L−1) and PIC (300 μmol L−1), totaling 44.33 and 76.33 embryos, respectively. Moreover, proembryos, embryogenic clusters, and somatic embryos were clearly visible. Embryogenic and meristematic cells presented marked staining of the cytoplasm, spherical shape of the cells and nucleus, and rapidly dividing nucleoli. Maturation of explants induced with 2,4-D and PIC was improved by adding 2iP (12.3 μmol L−1), NAA (0.6 μmol L−1), and AC (0.3 g L−1). During germination, BAP (1 μmol L−1) and GA3 (0.5 μmol L−1) promoted primary root protrusion and emergence of the shoot. In summary, PIC (300 μmol L−1) is suggested for embryogenic induction of E. edulis calli, and medium containing 2iP, NAA, and AC is suggested for maturation. Finally, medium containing BAP and GA3 without an auxin pulse favors the conversion of E. edulis somatic embryos into plants.

Density Functional Theory (DFT) as a Nondestructive Probe in the Field of Art Conservation: Small-Molecule Adsorption on Aragonite Surfaces.

Humans have incorporated minerals in objects of cultural heritage importance for millennia. The surfaces of these objects, which often long outlast the humans that create them, are undeniably exposed to a diverse mixture of chemicals throughout their lifetimes. As of yet, the art conservation community lacks a nondestructive, accurate, and inexpensive flexible computational screening method to evaluate the potential impact of chemicals with art, as a complement to experimental studies. In this work, we propose periodic density functional theory (DFT) studies as a way to address this challenge, specifically for the aragonite phase of calcium carbonate, a mineral that has been used in pigments, marble statues, and limestone architecture since ancient times. Computational models allow art conservation scientists to better understand the atomistic impact of small-molecule adsorbates on common mineral surfaces across a wide variety of environmental conditions. To gain insight into the surface adsorption reactivity of aragonite, we use DFT to investigate the atomistic interactions present in small-molecule-surface interfaces. Our adsorbate set includes common solvents, atmospheric pollutants, and emerging contaminants. Chemicals that significantly disrupt the surface structure such as carboxylic acids and sulfur-containing molecules are highlighted. We also focus on comparing adsorption energies and changes in surface bonds, which allows for the identification of key features in the electronic structure presented in a projected-density-of-state analysis. The trends outlined here will guide future experiments and allow art conservators to gain a better understanding of how a wide range of molecules interact with an aragonite surface under variable conditions and in different environments.

Contributors

Contributors

Micro to Nano: Multiscale IR Analyses Reveal Zinc Soap Heterogeneity in a 19th-Century Painting by Corot.

Formation and aggregation of metal carboxylates (metal soaps) can degrade the appearance and integrity of oil paints, challenging efforts to conserve painted works of art. Endeavors to understand the root cause of metal soap formation have been hampered by the limited spatial resolution of Fourier transform infrared microscopy (μ-FTIR). We overcome this limitation using optical photothermal infrared spectroscopy (O-PTIR) and photothermal-induced resonance (PTIR), two novel methods that provide IR spectra with ≈500 and ≈10 nm spatial resolutions, respectively. The distribution of chemical phases in thin sections from the top layer of a 19th-century painting is investigated at multiple scales (μ-FTIR ≈ 102 μm3, O-PTIR ≈ 10-1 μm3, PTIR ≈ 10-5 μm3). The paint samples analyzed here are found to be mixtures of pigments (cobalt green, lead white), cured oil, and a rich array of intermixed, small (often ≪ 0.1 μm3) zinc soap domains. We identify Zn stearate and Zn oleate crystalline soaps with characteristic narrow IR peaks (≈1530-1558 cm-1) and a heterogeneous, disordered, water-permeable, tetrahedral zinc soap phase, with a characteristic broad peak centered at ≈1596 cm-1. We show that the high signal-to-noise ratio and spatial resolution afforded by O-PTIR are ideal for identifying phase-separated (or locally concentrated) species with low average concentration, while PTIR provides an unprecedented nanoscale view of distributions and associations of species in paint. This newly accessible nanocompositional information will advance our knowledge of chemical processes in oil paint and will stimulate new art conservation practices.

Multi-Analytical Investigations of Andy Warhol's "Orange Car Crash": Polymeric Materials in Modern Paints.

This work presents strategic multi-analytical investigations performed on “Orange Car Crash” by Andy Warhol in order to make a well-informed conservation decision. For determining the type of binding medium used in the artwork, Pyrolysis–Gas Chromatography/Mass Spectrometry (Py–GC/MS) and Thermally Assisted Hydrolysis and Methylation of GC/MS (THM–GC/MS) were employed. The presence of a coating was investigated by Py–GC/MS. Moreover, the comprehension and elucidation of the paint stratigraphy were studied by examining cross-sections of samples taken from both canvases with Optical Microscopy (OM) under reflected visible (Vis) and ultraviolet light (UV) and by Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy (SEM–EDX). The investigation of possible synthetic organic pigments (SOPs) and extenders was performed by µ-Raman spectroscopy, while micro-Attenuated Total Reflection of Fourier-Transform Attenuated Total Reflection (µ-ATR–FTIR) allowed us to assign each component detected by Py–GC/MS or THM–GC/MS to a specific layer. The data collected from “Orange Car Crash” show mostly the application of acrylic-based paint as well as alkyd with rosin acids-based ink, thus providing fundamental information about the paint stratigraphy and chemical composition of each layer. In addition to the goal of informing an appropriate conservation–restoration strategy, this work represents a rare scientific study of a work by Andy Warhol.

The emergence of Liu Kang\u2019s new painting style (1950\u20131958): a multi-analytical approach for the study of the artist\u2019s painting materials and technique

Liu Kang (1911–2004) was renowned Singapore artist trained in Shanghai and Paris, and known for his contributions to the Nanyang style—an art movement practised by migrant Chinese painters in Singapore between the late 1940s to the 1960s. The style depicts aspects of the tropical way of life, synthetising the artistic traditions of the School of Paris and Chinese ink painting with remarkable stylistic innovations. The aim of this study was to characterise Liu Kang’s painting materials and technique by way of ten paintings from a significant period in his oeuvre, 1950–1958, during which his Nanyang style emerged. The selected artworks are from the National Gallery Singapore. A broad range of analytical techniques was employed to study the painting supports and paint layers. The results indicate the prevailing use of commercially prepared linen canvases with double-layered oil-based ground. Single- and triple-layered structures of the ground, as well as semi-absorbent ground, were used sporadically. The identified group of pigments partially overlaps with those already known from Liu Kang’s earlier practice and also incorporates some noteworthy peculiarities like manganese, cerulean and phthalocyanine blues, phthalocyanine green, zinc yellow, and naphthol red AS-D. Some of these newly identified pigments made a distinctive appearance in the individual artworks, but ultimately Liu Kang was not convinced about increasing their role in his painting practice of the 1950s as presented in this research. This study highlights the significance of drawing and photography as integral elements of his artistic process. It also delves into the artist’s different painting approaches and discusses their evolution, which culminated in the stylistic innovation that became Liu Kang’s signature for decades to come. The obtained data may assist art historians and conservators in authenticity and attribution studies, evaluating the condition of artworks and designing conservation strategies. Moreover, this study contributes to the growing body of knowledge about twentieth-century artists’ materials, which are characterised by the complex mixtures of inorganic and organic compounds. It also provides information about the availability of art materials in Singapore in the 1950s.