Cultural Heritage

Calcium oxalate films on works of art: A review Publication date: Available online 14 June 2019 Source: Journal of Cultural Heritage Author(s): Laura Rampazzi Abstract This work presents a review of the findings of calcium oxalate films, a widespread decay phenomenon recovered on stone and other substrates (mortars, wall and easel paintings, written materials, glass). The specific attention given to the issue in the 1990s has decreased, although articles have documented films until the present day. The review provides critical insights into the literature, focusing on the general properties of films, numerous case studies, the instrumental techniques used to characterise and date films, insights into the possible origin of the decay phenomenon, and an evaluation of the protective role of calcium oxalate layers. The practice of creating artificial films on stone surfaces for protective purposes is also considered. An evaluation of the literature over the last few decades shows various open issues. The origin is still up for debate, and the issue is still of major concern to conservation scientists, conservators, and restorers. The scientific community tends to attribute a biological origin to these films, however further studies are needed to study exactly how they form, focusing for example on simulation tests of the chemical and atmospheric pathway. How these films protect the artwork in terms of the mechanical properties of the surface underneath deserves more study. This would also help restorers to reproduce the calcium oxalate. The bibliography highlights the prevalence of calcium oxalate findings in the Mediterranean Basin and the formation of the least stable form, i.e. weddellite, which has yet to be explained.

Virtual reality in maritime archaeology legacy data for a virtual diving on the shipwreck of the Mercurio (1812) Publication date: Available online 14 June 2019 Source: Journal of Cultural Heritage Author(s): Massimiliano Secci, Carlo Beltrame, Stefania Manfio, Francesco Guerra Abstract Virtual Reality is becoming a complete and original way to leverage the enormous potential of the underwater cultural heritage world. In this paper, we illustrate how we used this tool and other 3D reconstruction to create a virtual experience on the Mercurio shipwreck. The brig Mercurio, sunk during the Battle of Grado (1812), currently lies at a depth of 17 m in the northern Adriatic Sea. Artifacts recovered during investigations made by the Università Ca' Foscari are now exposed in the Museum of the Sea in Caorle where a multimedia station has been installed. In order to create the virtual dive on this site, it was necessary to process legacy data from the photogrammetry surveys made during the excavation campaigns carried out when VR was unknown in archaeology. The paper presents this original way to create a virtual dive on an ancient shipwreck from archival and heterogeneous data.

Microstructure imaging of Florentine stuccoes through X-ray tomography: A new insight on ancient plaster-making techniques Publication date: Available online 11 June 2019 Source: Journal of Cultural Heritage Author(s): Florian Beaugnon, Gianluca Gariani, Emmanuelle Gouillart, Anne Bouquillon, Marc Bormand, Gilles Wallez Abstract Gypsum-based plasters or stuccoes, in spite of their importance and diffusion, received little attention in cultural heritage materials studies. This work introduces a new, non-destructive methodology, using micro-tomography to measure the water/plaster ratio and the morphology of the hemihydrate powder used to make plasters on < 1 mm3 samples. This methodology give insight in both the raw material (and ultimately provenance) and the technique used to make plaster. The methodology was tested first on mock-up samples of known composition, then in a case study on 13 low-relief cast plaster sculptures from 15th century Florentine artists. Preliminary conclusions on this limited corpus show relative uniformity across most reliefs in terms of raw materials and techniques. The casts of one model (Nativity, attributed to Donatello and B. Bellano) were made with a different raw material, in line with prior geochemical analyses; these results support the previous attribution to a North Italian rather than Florentine origin. The casts of a second model (Virgin and Child, type of Saint Petersburg, attributed to Antonio Rossellino) were prepared with a different technique. This surprising result was not expected from Art History or previous studies.

Application of imaging polarimeters to enhanced detection of stone carving Publication date: Available online 11 June 2019 Source: Journal of Cultural Heritage Author(s): Haifeng Wang, Yongquan Luo, Caidan An, Songnan Chu, Zhixue Shen, Lixian Huang, Dayong Zhang Abstract The enhanced detection and identification of stone carvings is significant for the remote sensing and digital museum project of cultural relic. In addition, imaging polarimeters have the potential to be efficient detectors owing to their superiority in terms of their capability of recognizing object contours and surface roughness. In this paper, the polarization changes of stone materials with different angles and varying degrees of roughness are theoretically analyzed and detected by a high-precision imaging polarimeter based on the liquid crystal variable retarder (LCVR) innovatively. It is observed that the detection of carving characteristics is enhanced in polarized imaging owing to the depressed background and enhanced contrast. The experimental finding indicates that polarized imaging has an exciting function in the remote sensing of stone carvings and enhanced detecting of the fuzzy inscriptions. This kind of specialized photography complements other, equally important recording techniques in the quest for comprehensive documentation of faint carvings.

The pigments of the frigidarium in the Sarno Baths, Pompeii: Identification, stratigraphy and weathering Publication date: Available online 11 June 2019 Source: Journal of Cultural Heritage Author(s): Ivana Angelini, Yotam Asscher, Michele Secco, Matteo Parisatto, Gilberto Artioli Abstract In the present research is used a multi-analytical approach to study the wall paintings from the Sarno Baths, located in the southern part of Pompeii. In particular the investigation is focused on the frescos of the frigidarium, though a few samples from other rooms were also analysed. Twenty wall paintings fragments were analysed by laser scanning confocal microscopy (LSCM), optical microscopy (OM), μ-Raman, scanning electron microscope with energy dispersive spectrometry (SEM-EDS), portable X-ray fluorescence spectrometry (p-XRF) and X-ray powder diffraction (XRPD). The XRPD data were used for the mineralogical semi-quantitative phase analyses (SQPA) and the estimation of the hematite crystals size. The obtained data allow the identification of the pigments and the techniques used, and address new question such as whether talc and aragonite were used routinely in the formulation of pigments. The chemical composition of red and yellow pigments is also discussed and compared with data available from the recent literature. The wall paintings are badly preserved and weathering products occur on the pictorial surface. Eight samples of efflorescence salts and patinas were analysed by XRPD: all the samples are composed mainly by alkali sulphates. The systematic difference between the salts present on the northern and the western walls is likely related to the materials inserted during the 19th century restauration.

The deposition from the Cross in the church of Saint-Germain-en-Laye (France): A masterpiece of Romanesque sculpture? Materials characterization to solve a 20th c. mystery Publication date: Available online 10 June 2019 Source: Journal of Cultural Heritage Author(s): Alessia Coccato, Luciana Mantovani, Romano Ferrari, Danilo Bersani, Mario Tribaudino, Pier Paolo Lottici Abstract Dating and authenticating stone-sculpted works of art is a challenging aspect of cultural heritage studies. In fact, it is often possible to provenance the rock, by comparison of petrological, mineralogical and geochemical data, but no dating of the sculpture can be obtained. Also, stylistic observations need to be considered with care. However, in the case of mastic incrustation sculptures, the applied polychromy can support dating studies, based on pigments and binders. In the church of Saint-Germain-en-Laye, a haut-relief representing the Deposition from the Cross is exposed. The calcareous slab is decorated with red and black mastics. It resembles closely the Deposition from the Cross in the transept of Parma Cathedral, dated 1178 and "signed" by Benedictus Antelami. However, the St-Germain Deposition appeared in 1994, when it was donated to the parish by the descendants of Julien Auguste Duperrier, marble worker and collector of Italian antiquities. His last trip to Italy took place in 1924. No information is available on his deal, neither on the transport means arranged, nor on the sculpture itself (author, contractor, date, etc.). Art historical and historical considerations propose either a 12th or 19th–20th c. context for the creation of the sculpture. Chemical analyses of the pigments and binders are therefore proposed to clarify the dating the work of art. Microscopic samples are characterized by a multi-analytical approach: vibrational spectroscopies and X-ray powder diffraction are used to characterize the rock and the polychrome mastic. The rock is identified as a micritic limestone, and shows sulphation issues. Through Raman scattering measurements, the pigments were identified: carbon in the black mastic, and a mixture of red lead and a modern synthetic pigment (PR49:1) in the red areas. This information sheds new light on the chronology and manufacture of the Deposition from the Cross of Saint-Germain-en-Laye. These results allow for a better definition of further lines of research, and to finally propose an authorship for the sculpture.

Erratum to "Investigation of cellulose nitrate and cellulose acetate plastics in museum collections using ion chromatography and size exclusion chromatography" [J. Cult. Herit. (2019) 263–70] Publication date: Available online 10 June 2019 Source: Journal of Cultural Heritage Author(s): Joy Mazurek, Anna Laganà, Vincent Dion, Suzanna Etyemez, Carolyn Carta, Michael R. Schilling

Mitigating salt damage in building materials by the use of crystallization modifiers – a review and outlook Publication date: Available online 5 June 2019 Source: Journal of Cultural Heritage Author(s): Sanne J.C. Granneman, Barbara Lubelli, Rob P.J. van Hees Abstract Salt crystallization damage in porous building materials is a widespread phenomenon. Several solutions to prevent, or mitigate, salt damage in building materials, prolonging thereby their service-life have been proposed. One of the latest approaches is the use of crystallization modifiers, aiming at reducing the crystallization pressure and/or favouring the crystallization of salts at the surface (efflorescence) instead of in the pores of the materials (crypto-florescence1). This paper summarizes the working mechanisms of crystallization modifiers and critically reviews the available literature on their use in building materials; finally, it provides an outlook on the potentials of modifiers for the mitigation of salt crystallization damage in building materials.

Visual information retrieval from historical document images Publication date: Available online 4 June 2019 Source: Journal of Cultural Heritage Author(s): Sara Zhalehpour, Ehsan Arabnejad, Chad Wellmon, Andrew Piper, Mohamed Cheriet Abstract Information retrieval from documentary heritage is considered a challenging issue because of the documents' unique structures and level of degradation. Text characters in printed documents historically are accompanied by typographical objects. Retrieving and pursuing these visual typographical elements, which inform the content of historical manuscripts can help us better understand our documentary cultural heritage. Extracting these visual objects aids us in understanding and conveying more information about different practices of representation in historical documents and their effects on the current trends of publishing. Two important typographical objects related to the history of knowledge and information are footnotes and tables; the former are one of the critical elements that demonstrate authority and link the manuscript to its sources, and the latter summarize information in a compact and organized manner essential to the growth of scientific knowledge. To the best of our knowledge, there is currently no work that considers in depth the automated detection of these two typographical objects from the large collections of historical documents that would allow further historical study. This article focuses on the problem of detecting the presence of these two visual elements from historical printed documents and establishes two frameworks. The footnote detection framework uses a set of layout-based methods to extract some features regarding the font and appearance, and the table detection framework extracts spectral-based features from the images. These frameworks are tested on a large collection of 18th-century printed documents with more than 32 million images, and the results show their effectiveness and generalization power.

Changes in biodeterioration patterns of mural paintings: Multi-temporal mapping for a preventive conservation strategy in the Crypt of the Original Sin (Matera, Italy) Publication date: Available online 2 June 2019 Source: Journal of Cultural Heritage Author(s): Giulia Caneva, Flavia Bartoli, Martina Fontani, Doretta Mazzeschi, Paolo Visca Abstract Multi-temporal investigation of biodeterioration patterns (BPs) in cultural heritage sites is crucial for the development of effective management plans. Here, microscopy and biomolecular methods were employed to analyze the BPs, which took place in the Crypt of the Original Sin (Italy) over a wide temporal scale, i.e., from 2001 to 2017. Before restoration interventions, performed in 2002–2003, a variety of BPs was observed, including green patinas (Chlorophyceae), brown-black patinas (Cyanobacteria), rosy discolorations (Actinobacteria) and some colonization by lichens, mosses and ferns. Restoration included biocide treatments as well as structural interventions causing environmental modifications of the site. To interpret the ecological relationships between environmental factors and temporal changes, we combined the analysis of ecological information on the various BPs with the results of a multivariate statistical analysis. Using BPs as bioindicators, humidity maps of the plasters were generated and water infiltration paths reconstructed. Several years after biocide application, a significant reduction of BPs was observed, together with limited colonization by dematiaceous and meristematic fungi. Our observations demonstrate the usefulness of combining structural and environmental interventions for an effective restoration strategy; these interventions reduced the moisture levels of the walls, consequently reducing biological colonization. Moreover, our findings suggest that monitoring BPs during time can be of guidance in the long-term maintenance of cultural heritage, and provide an evidence-based model for preventive interventions and biocide treatments. Graphical abstract

Alexandros Sfakianakis
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alsfakia@gmail.com