Journal of Cultural Heritage最新文献

The digital technologies employed in archaeology since the 1990s have progressively and experimentally been utilized over the last two decades to document and re-present the ancient polychromy of Greek and Roman marble artworks. Given that this remains a developing field of investigation and application, this study offers, for the first time, a systematic review of the endeavours undertaken thus far in implementing information technology for the documentation, analysis, reconstruction, visualization, and presentation of ancient polychromy. This overview is supported by a literature review and existing implementations, organized into methods and techniques employed for 3D colour preservation, analysis, and reconstruction, as well as those used for the visualization and dissemination of findings. The goal is to identify gaps and provide intriguing insights for future research concerning the use of digital technologies as an essential tool in the stages of documenting and disseminating ancient polychromy in architecture and archaeological artefacts. This, in turn, aims to encourage data sharing, contribute to the dissemination of science-based knowledge and resolve substantial barriers associated with the long-term retention of digital data.

A prominent feature in Portuguese historic architecture is Portugal’s azulejos or tiles that cover cultural heritage buildings with colorful patterns. However, tiles are prone to deterioration due to the quality of masonry materials, exposure over time, and natural and human factors. A careful approach is necessary to detect and assess tile damage in time to conserve cultural heritage. Deep learning (DL) methods are applied to detect deterioration and damage by automating vision-based monitoring. This study uses the You Only Look Once (YOLO), method to detect deterioration in tiles automatically. To obtain the initial dataset, over 5000 images of damage were collected, including cracks, craters, glaze detachment, and tile lacunae, as well as images with no defects. Additionally, a MobileNet model was used for binary classification of damaged and intact tiles to compare classification and detection approaches. Through the fine-tuning of hyperparameters and updating the dataset, an overall accuracy of over 72% for YOLO (multiple classification) and 97% accuracy for binary classification was achieved, demonstrating the adequacy of the tool for real-world applications.

A unique anthropomorphic statue, representing a young man standing tall ca. 50 cm. and primarily made of ivory and with gold decorative elements, was discovered heavily fragmented and burnt during the extensive excavations at the Bronze Age site of Palaikastro in Crete, Greece in 1987, 1988 and 1990. Through a painstaking restoration process of nearly a decade long, the statue was brought back to its original shape from ca. 200 recovered fragments and it is now exhibited in the Siteia Archaeological Museum in East Crete. The statue and the remaining fragments that the conservators were not able to refit on the statue were recently 3D documented by means of a high-precision optical scanner, resulting in the virtual re-positioning of many remaining fragments, correction of the statue's right foot orientation and its overall posture, and a better understanding of its assembly technique. This article presents these results and the digital processes that lead to them.

The Norwegian Sea Trade Archive (NST Archive) from the University of Bergen Library, Norway, is part of the UNESCO documentary heritage and contains unique documentation of the activity of companies that traded in stock fish in Norway and Europe (16th-20th century). The archive consists primarily of bound paper manuscripts written mostly in brown ink. We have surveyed this collection using a multi-analytical approach focused on the material characterization and condition of the paper carrier and inks. Our main aim was to support decision-making on establishing storage conditions, digitisation priorities, and type and extent of conservation treatments necessary to make the collection accessible.

After a first visual examination to detect and quantify damages, for the paper support analysis we measured surface pH, paper thickness and water absorbency. Additionally, on a quarter of all tested materials, we performed a SurveNIR analysis, providing information regarding paper pulp type, lignin, protein and rosin content, degree of polymerization, and mechanical properties. The archival material was grouped into three periods characterising the three milestones in paper production: handmade gelatine-sized rag papers, machine-made rag papers with gelatine and rosin sizing, and papers made from processed wood pulp.

Regarding the manuscripts’ inks, we used iron and copper tests to determine the presence of Fe², Cu²⁺ and Cu⁺ions, respectively. For the visual characterization and condition rating of the inks, we used the protocols described by the Netherlands Institute for Cultural Heritage. The variety of ink colours and thickness of the inked lines encountered in each document was noted down. Thus specific tendencies present in each historical period became apparent. Results of the solubility of ink in water and alcohol significantly narrowed treatment options.

General tendencies of paper and ink degradation based on differences in papermaking were observed. Surface pH measurement, SurveNIR pH, rosin and protein concentration data showed that most rag papers were of poor to fair quality (pH ≤ 6.0 and low protein content (< 5 %)). Rosin-sized papers dated after 1840 had a lower pH (from 3.3 ± 0.2 to 5.0 ± 0.2) compared to gelatine-sized ones. Based on the obtained results, the overall condition of all the papers is good – slightly damaged but stable. The inks are not severely corroded, and there is no loss of text, although 20 % of the collection does show signs of iron-gall ink (IGI) corrosion. A limited number of documents, mostly before 1800, would require local antioxidative treatment. Due to the low pH of all the papers and the detection of ink corrosion, the collection should be stored in a cool environment, with low relative humidity.

After the survey, digitisation priorities were also established.

One of the problems that arises when applying 3D Structure from Motion and Multi-View-Stereo photogrammetry to certain heritage objects characterized by minimal surface features and monochrome textures is that the obtained 3D models have low quality and accuracy. Within such scenarios, the smallest lengths that can be measured on it with high accuracy is usually one or more orders of magnitude worse than the maximum resolution of the input photographs. Additionally, when contrasted with outputs from scanning systems, these reconstructions tend to exhibit relatively lower quality. This article presents a simple approach wherein the incorporation of normal maps acquired through Reflectance Transformation Imaging technique improves the quality and accuracy of 3D photogrammetric reconstructions (mesh + texture). This enhancement also surpasses the capabilities of some commercial structured light scanning systems and reaches values that are in the order of magnitude of the maximum resolution of the photographs used.

The present work describes the high potential of the recently developed synchrotron X-ray diffraction computed tomography (XRDCT) for 3D mapping of crystalline and amorphous phases in Geomaterials of Cultural Heritage (CHG). The paper critically discusses the promising results and limitations of XRDCT in Cultural Heritage applications. XRDCT has been applied herein to diverse CHG materials, spanning from archaeological ceramics, and stone conservation treatments to meteorites, at a microscale. Although these materials are very complex systems from a chemical, mineralogical and microstructural point of view, this innovative technique proves effective capability to access the real spatial distribution and semi-quantification of crystallographic phases within materials in a totally non-destructive and/or non-invasive way.

This paper studies the effectiveness of four consolidation treatments based on nanoparticles suspensions: calcium hydroxide (Ca-NP), magnesium hydroxide (Mg-NP), a treatment combining calcium hydroxide and magnesium hydroxide (Ca/Mg-NP), and a treatment consisting of calcium hydroxide and silicon dioxide (Ca/Si-NP) that were both applied separately. The suspensions were sprayed on gypsum plasters and lime renders which are common substrates in historical constructions and show a high degree of similarity with the treatments. The consolidation efficiency was evaluated using non-destructive techniques, such as peeling test, Shore-D hardness, water flow using Karsten tube and water vapour permeability tests. In addition, TEM images and XRD tests demonstrated the formation of a new C-S-H cementing phase when Ca/Si-NPs were combined due to a reaction between Ca(OH)₂ with SiO₂. Colour tests (CIE-L*a*b*) showed the consolidants did not produce major colour alterations, although the Ca-NP treatment caused a slight lightness increase. The strengthening effect was greater in lime mortars and water flow was moderately reduced in all treatments, except in mortars coated with Ca/Mg-NP. Finally, the chemical nature of the treatments is similar to the substrates, and they did not significantly alter the water vapour permeability of the studied materials.

Aged animal glues degrade and weaken over time, resulting in flakes and cracks on the material employed by wooden manufacturers and luthiers. Because of this deterioration, conservators and restorers remove aged water-soluble glues with a water swab, smoothing enough to clean them mechanically and putting on new reversible glues. However, it raises the question of whether a water swab can control moisture delivery while removing glue from wood, a hygroscopic and water-sensitive material.

This study formulated a chemically crosslinked film-forming hydrogel based on sodium alginate (SA) with (3-Glycidoxypropyl)trimethoxysilane (GPTMS) and calcium chloride, named as CA-GPTMS to construct a retentive gel. Synthesized gel materials were characterized using several methods: liquid state NMR, FTIR-ATR, and SEM-EDS analyses were involved in examining the cross-linking process, while moisture and mechanical properties were examined to understand its suitability for the cleaning application process. The strategies for applying the CA-GPTMS gel on wood surface were to selectively soften the glue and to remove it as well as leave no residues on the wood surface. The cleaning process was investigated by using different techniques, i.e., stereomicroscopy, reflection-FTIR, and SEM-EDS. Compared to traditional rigid Agar gel, the CA-GPTMS gel appeared successfully resistant to destruction and was suitable for application on highly water-sensitive surfaces.

The traditional mounting process involves a critical and time-consuming board-restraint procedure. It is widely acknowledged in practice that the dimensional stability of a mounting improves with a prolonged restraint period on the drying board. Yet, the underlying reasons for the enhanced dimensional stability from long-term board-restraint are not well-understood. This study investigates the mechanisms at play through systematic experimentation. It was found that humidity cycling enhances the dimensional stability of the mounting by diminishing its hydroexpansivity and irreversible shrinkage. Specifically, humidity cycling induces fiber hornification, which reduces the hydroexpansivity of the mounting. Concurrently, it facilitates the redistribution of stresses and strains within the board-restrained mounting, mitigating internal stresses and the resulting irreversible shrinkage. This study contributes to a deeper understanding of the board-restraint procedure and how it affects the dimensional stability of the mounting.

Cherished amber relics have undergone long-period burial environments carrying several ageing deterioration characteristics, such as crazing, discolouration, and decreased hardness, which makes amber artefacts fragile. Ageing is inevitable for amber exposed to air, emphasising the need for a suitable preservation environment based on the ageing mechanism. However, related research, specifically on the transformed compositions and structures of archaeological amber, has been limited due to complexities in deciphering the intricate components. In this research, attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray fluorescence (XRF), inductively coupled plasma optical emission spectroscopy (ICP-OES) and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) were applied on geological and archaeological Baltic amber to find the ageing pathways. An untargeted metabolomics analysis developed for the linear modelling of molecular features data was utilised in combination with Py-GC/MS results, and statistically significant variations provided ten increased and ten decreased ageing markers. We propose an ageing mechanism for the succinite molecular structure, which involves oxidation of the polylabdanoid and hydrolysis of the esterification cross-link structure between succinic acid and labdanoid. Simultaneously, monoterpenes were released from the amber structure. Our untargeted Py-GC/MS metabolomics approach offers a groundbreaking and more systematic method for investigating the ageing mechanism of multi-component organic polymers in archaeological artefacts.