•High temperature and relative humidity increase the degradation rate.•Plasticizer type does not affect the degradation, the content does. High-MW polymers are more stable than shorter chains.•The ...activation energy of dehydrochlorination observed as yellowing is 86 ± 3 kJ/mol.•Use the damage function to predict lifetime of heritage objects.•Identify objects in collections prone to degradation.
Yellowing of plastic objects as a consequence of chemical degradation is a common heritage conservation challenge. In the case of poly(vinyl chloride) elimination of hydrogen chloride leads to the formation of polyene sequences that act as chromophores. The objective of this work was to quantitatively evaluate the rate of degradation observed as yellowing, as relevant to room conditions during long-term storage of heritage collections. Degradation was quantified as increase in the b* colour coordinate during accelerated degradation at 50 and 70 °C as a function of temperature, relative humidity, plasticizer content, and polymer molecular weight. The significance of each variable was investigated with multiple linear regression. Lower temperature, lower relative humidity, higher polymer molecular weight and higher plasticizer content were associated with lower degradation rates. The activation energy of 86 kJ/mol was calculated. The concept of ‘1- °C-equivalent’ is introduced to enable variable prioritisation from a heritage management aspect. The resulting model can be used to shape environmental management guidelines and identify the most vulnerable objects in heritage collections.
In this study, X-Ray Fluorescence Spectrometry (XRF), Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) and Secondary Ion Mass Spectrometry (SIMS) have been used to assess the ...transfer of ions between iron-gall inks and indicator papers soaked in 4:7-diphenyl-1:10-phenanthroline. Such indicators are commonly used in the conservation practice to detect Fe(II) ions and diagnose a presence of ink corrosion phenomena in historical manuscripts. For this purpose four different model inks with variable Fe:Cu proportions were prepared on the basis of gall nuts extract mixed with FeSO4.7H2O, CuSO4.5H2O and Gum Arabic. Obtained results indicate that apart from the main components of inks (S, Fe and Cu) also other elements can migrate to indicator test papers. Collected XRF and LA-ICP-MS data were consistent in their potential for reconstructing major elemental composition of model inks on the basis of indirect analysis with indicator test papers. LA-ICP-MS extended the range of learning into the trace elemental composition, while SIMS allowed observations of structurally significant fragment ions (ML2+, ML+, M+) where L = 4:7-diphenyl-1:10-phenanthroline and M = Fe or Cu ions.
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•XRF, LA-ICP-MS and SIMS were used to assess the transfer of ions between iron-gall inks and indicator papers soaked in Bphen.•Evidence that elements other than the main components (S, Fe and Cu) also migrate from inks to the indicator papers when used.•Fragment ions ML2+, ML+, M+ (where L=4:7-diphenyl-1:10-phenanthroline and M=Fe or Cu ions) were detected by SIMS.
The present research exploits the strengths of external reflection FT-IR spectroscopy to non-invasively study heritage plastic objects through inspection, for the first time, of the wide spectral ...range including the near- and mid-IR (12500-350 cm−1). Unlike most of previous works on historical plastic objects, reflection-mode spectra were not corrected for the unfamiliar surface reflection profiles to the more recognizable absorption-like band shapes. This avoided data misinterpretation due to ill-suited Kramers Krönig correction when volume reflection is also present or when highly absorbing IR compounds generate Reststrahlen bands.
The inspection of the enlarged spectral range allowed the detection of fundamental, combination and overtone bands which provided reliable identification and semi-quantitative characterization of different polystyrene-based co-polymers. Furthermore the variation of the plastic optical properties across the explored spectral range allowed us to sample the plastic materials to different depths in the mid- and near-IR regions, so as to probe the chemistry at the surface and in the plastic bulk, respectively, in a non-invasive manner. This proved particularly useful to observe spectral markers of surface degradation occurring in historical ABS-based polymers.
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•External reflection FT-IR for non invasive studies of historical plastic objects.•Non invasive identification of polymers.•Estimation of the relative content of monomers in PS-based co-polymers in historical plastic objects.•In situ monitoring of degradation markers in plastics for preventive conservation of historical plastic objects.
Laser-induced breakdown spectroscopy (LIBS) is a versatile elemental analytical technique whose basic elements were described as early as 1962, shortly after the invention of a pulsed laser. Since ...that time, LIBS has been applied for elemental characterization of various applications. In this work, we review the evolution of LIBS characterization of artworks' materials applications and the development of the LIBS technique for cultural heritage during the years 2015–2020. The LIBS technique has faced and overcome challenges by analytical studies of conservation/restoration and archaeological objects. These challenges required improvements in the LIBS technology in order to obtain good reproducible signals (high S/N, sensitivity) and more reliable quantitative analysis. They also encouraged the LIBS research community to focus on instrumentation development to minimize laser impact, to increase miniaturization (enabling in situ characterization), and to combine different spectroscopic techniques. We aim to encourage more people working on heritage science to use this technique, for whom LIBS may be a brand-new elemental analysis technique, and aim to motivate more LIBS researchers to continue developing the LIBS technique in order to address more issues on conservation, restoration, and archaeology.
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•LIBS for heritage science applications in the last six years.•Review of recent evolution of LIBS instrumentation from portable LIBS to hyphenated techniques.•New trend and needs in cultural heritage material characterization.
On the occasion of the upcoming twentieth anniversary of the adoption of the UNESCO Convention on the Safeguarding of Intangible Cultural Heritage , it is important to emphasise the role of ...intangible cultural heritage in preserving the identity of an individual nation. This paper analyses the Science and Social Studies textbooks for the 4th grade of elementary school. The aim of the paper is to determine the representation of intangible cultural heritage inscribed on UNESCO's list of cultural goods by analysing textbooks and to provide guidelines for approaching this topic. The review of textbooks revealed differences in the approach to coverage relating to content related to intangible cultural heritage in textbooks by different authors and different publishing houses. It was observed that different authors approach the topics of cultural heritage differently, and intangible heritage is represented differently in different textbooks. In the majority of textbooks, intangible cultural heritage inscribed on the UNESCO list is well presented, but it is mostly mentioned as such without additional explanations and visual representations. It is necessary to approach this topic in education in a way that will encourage students to be active and participate in preserving the intangible cultural heritage that is a part of each of them, with a textbook being just one of the available tools in the teaching process.
Povodom nadolazeće dvadesete obljetnice donošenja UNESCO-ove Konvencije o zaštiti nematerijalne kulturne baštine važno je istaknuti ulogu nematerijalne kulturne baštine za očuvanje identiteta pojedinog naroda. U radu je napravljena analiza udžbenika iz Prirode i društva za 4. razred osnovne škole. Cilj je rada bio analizom udžbenika utvrditi zastupljenost nematerijalne kulturne baštine koja je upisana na UNESCO-ov popis kulturnih dobara te dati smjernice za pristup ovoj temi. Pregledom udžbenika utvrđene su razlike u pristupu obrade sadržaja koji se odnose na nematerijalnu kulturnu baštinu u udžbenicima različitih autora i različitih izdavačkih kuća. Uočeno je kako različiti autori različito pristupaju temama kulturne baštine te je nematerijalna baština različito zastupljena u različitim udžbenicima. U većini je udžbenika dobra pojavnost nematerijalne kulturne baštine s UNESCO-ovog popisa, ali se ona kao takva uglavnom spominje bez dodatnih objašnjenja i slikovnih prikaza. Potrebno je ovoj temi u odgoju i obrazovanju svakako pristupati na način koji će poticati učenike na aktivno djelovanje i njihovo sudjelovanje u očuvanju nematerijalne kulturne baštine koja je dijelom svakoga od njih, a udžbenik je pri tome samo jedno od sredstava u nastavnom procesu.
The molecular characterization of organic materials in samples from artworks and historical objects traditionally entailed qualitative and quantitative analyses by HPLC and GC. Today innovative ...approaches based on analytical pyrolysis enable samples to be analysed without any chemical pre‐treatment. Pyrolysis, which is often considered as a screening technique, shows previously unexplored potential thanks to recent instrumental developments. Organic materials that are macromolecular in nature, or undergo polymerization upon curing and ageing can now be better investigated. Most constituents of paint layers and archaeological organic substances contain major insoluble and chemically non‐hydrolysable fractions that are inaccessible to GC or HPLC. To date, molecular scientific investigations of the organic constituents of artworks and historical objects have mostly focused on the minor constituents of the sample. This review presents recent advances in the qualitative and semi‐quantitative analyses of organic materials in heritage objects based on analytical pyrolysis coupled with mass spectrometry.
Analytical pyrolysis is experiencing previously unexplored potential, thanks to recent instrumental developments. Recent advances in the heritage field enable the investigation of several organic materials in artistic and historical objects that are macromolecular in nature, or which undergo polymerization upon curing and ageing, by strategies based on analytical pyrolysis coupled with mass spectrometry.
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•We demonstrate that Vasari’s “Coronation of the virgin” is a finished work.•Mapping and punctual techniques are used for non-invasive spectroscopic analyses.•Paper preparation, inks, ...and impurities are identified by μ-Raman, FTIR, and MA-XRF.•This work sheds light on Giorgio Vasari's sophisticated artistic techniques.
In the present paper, for the first time, non-invasive techniques have been employed to improve the knowledge of a Coronation of the Virgin dating back to 1560–70. This is an old master drawing by Giorgio Vasari, considered one of the major painters and art theoric of Italian late 16th Century. The adopted multi-technique approach, involving preliminary macroscopic and microscopic observations, and followed by X- ray fluorescence mapping (MA-XRF), μ-Raman, and Fourier Transform infrared spectroscopy (FTIR) analyses, along with the historical information, has allowed to identify the original materials and to understand the drawing's realization process. The results show that paper preparation has been realized by using a yellow mineral, namely goethite, in order to obtain a particular shade. Moreover, a proteinaceous component, likely animal gelatin, has been used as a binder for goethite or during the paper preparation process. Small white flakes, composed of lead white and massicot, have been randomly found on the surface of the drawing: the specific function and/or origin of these flakes is unknown. Finally, the use of black chalk for a preliminary sketch and iron gall ink for the final drawing has been observed.
Changing climatic conditions are contributing to faster deterioration of building fabric. Increasing number of heavy rainfall events can particularly affect historic and Cultural Heritage (CH) ...buildings. These evolving and uncertain circumstances demand more frequent survey of building fabric to ensure satisfactory repair and maintenance. However, traditional fabric surveys have been shown to lack efficiency, accuracy and objectivity, hindering essential repair operations. The recent development of reality capture technologies, together with the development of algorithms to effectively process the acquired data, offers the promise of transformation of surveying methods.
This paper presents an original algorithm for automatic segmentation of individual masonry units and mortar regions in digitised rubble stone constructions, using geometrical and colour data acquired by Terrestrial Laser Scanning (TLS) devices. The algorithm is based on the 2D Continuous Wavelet Transform (CWT), and uniquely it does not require the wall to be flat or plumb. This characteristic is important because historic structures, in particular, commonly present non-negligible levels of bow, waviness and out-of-verticality.
The method is validated through experiments undertaken using data from two relevant and highly significant Scottish CH buildings. The value of such segmentation to building surveying and maintenance regimes is also further demonstrated with application in automated and accurate measurement of mortar recess and pinning. Overall, the results demonstrate the value of the automatic segmentation of masonry units towards more comprehensive and accurate surveys.
•We present an algorithm for automatic segmentation of stones in digitised walls.•It is uniquely based on the 2D CWT and can effectively handle curved and wavy walls.•The method has been validated through experiments in significant historic buildings.•Results prove the potential of the method towards more objective & accurate surveys.
This paper provides new insights for the study of polymer degradation through the detection of markers released at the polymer surface using Al-coated SERS active substrates. Combining a ...nanodestructive sampling procedure with the SERS sensitivity allows achieving detection limits much lower than traditional polymer characterization techniques, opening the way to the use of SERS as part of an innovative strategy to diagnose surface degradation in polymeric museum artefacts. The method was applied to artificially photo-aged model polymers and to museum artworks.
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•Combination of a nanodestructive sampling procedure with SERS to detect polymer degradation products.•Identification of degradation markers released at the surface of polymeric materials.•Achieving of detection limits lower than those of traditional polymer characterization techniques.•Potential diagnose tool kit for deterioration of plastic artworks and museum objects.
Abstract
The goal of the Vilhelm Hammershøi Digital Archive project of the National Gallery of Denmark is to understand the Danish painter Vilhelm Hammershøi's painting methods by compiling a ...comprehensive amount of data on his use of materials and working methods through visual and technical examination of a large number of his paintings, and to make this information available to researchers and the public in an open access digital resource. A clear understanding of the full suite of pigments across the paintings requires determination of which materials comprise the palettes of the ground and paint layers. Scanning electron microscopy/energy‐dispersive x‐ray spectroscopy and macro x‐ray fluorescence spectroscopy were selected as the key analytical techniques due to their ability to yield chemical information at the elemental level. This article presents a method that combines unsupervised machine learning and cluster analysis techniques, to automatically reduce the large x‐ray spectral data to sets of distinct clusters that share similar spectra, making it possible to identify materials more precisely. The proposed method allowed the grouping of materials by chemical composition, which enabled an optimal understanding of the pigments used in the ground layers sampled from a large number of paintings as well as in the paint layer examined at the surface of one selected painting. The method performed well when compared with other well‐established data mining techniques, and it helped reduce the time necessary for the interpretation of the analytical results significantly. Through this approach, a basis for a more nuanced view of Hammershøi's artistic idea and technical development will be generated.
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