Tempera Paint Research Articles

Determination of Antimicrobial Activity in Fungi-destructors of Tempera Painting Isolated in the State Tretyakov Gallery

Determination of Antimicrobial Activity in Fungi-destructors of Tempera Painting Isolated in the State Tretyakov Gallery

Search for new materials based on chitosan for the protection of cultural heritage

Microorganisms are a significant cause of damage to cultural heritage, including paintings. Currently, the palette of antiseptics that are used in painting has narrowed considerably. This is due to the increased demands placed on such substances. It was shown that low molecular weight chitosan (LMWC) obtained from the king crab (Paralithodes camtschaticus) exhibits high activity against dominant fungi-destructors of paintings in the State Tretyakov Gallery. Nevertheless, the increasing market demand for chitosan has prompted the exploration of alternative sources. Insects, notably the bioconverter black soldier fly (Hermetia illucens), stand out as one of the most cultivated options. This study investigates the effectiveness of chitosan, isolated from H. illucens by a novel method developed by authors, in inhibiting fungi that damage tempera paintings. The activity of 33 and 39 kDa chitosans from H. illucens is comparable to the most active chitosans previously studied from P. camtschaticus. However, there are characteristic differences between these compounds, as shown by the results of FTIR spectroscopy, which may affect their consumer properties when used in paint materials. Our studies suggest that LMWC from H. illucens is a promising material that can expand the range of antiseptics used in painting.Graphical

Artworks at our fingertips: A solution starting from the digital replication experience of the Annunciation in San Giovanni Valdarno

The Annunciation is a remarkable artwork painted in the early 1430s by the Dominican friar Giovanni da Fiesole, better known as Beato Angelico, and now preserved at the Museum of the Basilica of Santa Maria delle Grazie in San Giovanni Valdarno, Italy. It is a wide tempera painting with some fine gold foil placed on a wooden support, representing many symbolic details hard to be fully appreciated at a distance by the observer. To enhance the museum's visitor experience on it, as well as providing scholars with a tool to help deep investigations, a digital high-resolution Digital Twin of the painting was developed. This paper summarizes the outcomes of the process, introducing the custom software applications and hardware solutions that were customized for the artwork's digital replication. Exploiting digital photogrammetry and photometric stereo techniques, the model was prepared to host colorimetrically corrected maps at Gigapixel resolution, reaching a high-definition measurable detail threshold and following a well-established process refined over time by the authors. The fruition of such a complex model was performed through a custom process ending in AnnunciatiOn App, a solution integrated by both graphical and physical touch interfaces, whose features grant a deep interaction with the Digital Twin on kiosks destined to exhibitions. The results feed the discussion on the production and communication of digital replicas of artworks in museum collections and how they can be upscaled to be targeted to simple visitors as well as scholars and restorers.

Mechanical and moisture-related properties of selected dried tempera paints

Mechanical properties—modulus of elasticity and strain at break, water vapour sorption, and hygroscopic expansion of selected egg tempera and distemper paints were determined as a function of relative humidity (RH) filling in this way a critical gap in the knowledge required for the analysis of fracturing processes in paintings. The experimental work was made possible by the preparation of several tempera paints, mimicking the historical materials, in the form of large specimens. Lead white, azurite, and yellow ochre were selected as pigments, and egg yolk and rabbit skin glue as binding media. The water vapour sorption and the moisture-related swelling of the paints were dominated by the proteinaceous components of the binders. The linear hygroscopic expansion coefficient of the dried egg yolk binder was approximately 1 × 10−4 per 1% RH, several times less than the coefficient of the collagen glue (4 × 10−4 per 1% RH). The moduli of elasticity of egg tempera paints at the RH mid-range were comparable to the moduli of aged oil paints, whilst the modulus of elasticity of the distemper paint was close to values measured for animal glue-based grounds. The paints experienced the transition from brittle to ductile states on increasing RH. The egg tempera paints were found to be more brittle than the distemper paint, gessoes, and, generally, aged oil paints. The observations modify a frequently used laminar model of panel paintings in which the mismatch in the response of glue-based ground layer and wood substrate to variations in RH has been identified as the worst-case condition for the fracturing of the entire pictorial layer. This study demonstrated that tempera could be more brittle than the ground layer and in consequence more vulnerable to cracking.

Diving into micro- and macroscopic properties of egg-tempera paint based on Sienna pigment

Egg-tempera painting was a pictorial technique widespread in the Middle Ages. In this work, Sienna earth and yolk have been used to formulate tempera paints according to historical recipes. Micro- and macroscopic properties were investigated to understand the interactions between the pigment and the binder. The pigment, inorganic part of the paint, was characterized by X-Ray Diffraction (XRD), thermal analysis (TG-DTA), Fourier Transform Infrared (FT-IR) Spectroscopy, granulometry, as well as Scanning Electron Microscopy (SEM). Then lecithin adsorption onto pigment particles was probed to understand yolk interaction with Sienna earth, pure kaolinite and goethite particles. NMR-Relaxometry was used to investigate the behavior and accessibility of the mineral surfaces to yolk and water. Macroscopic rheological properties of the paint systems were finally investigated.

ХУДОЖЕСТВЕННЫЕ ОСОБЕННОСТИ РОССИЙСКИХ ПРОМЫСЛОВ ЛАКОВОЙ МИНИАТЮРЫ В СОВРЕМЕННОМ ДЕКОРАТИВНОМ ИСКУССТВЕ И ДИЗАЙНЕ

This article examines the Russian crafts of lacquer miniature painting in the context of the manifestation of their artistic features in modern decorative and applied arts and design. The authors’ goal is to identify stylistic techniques of Russian varnishes and analyze the possibilities of using authentic characteristics of folk art in the author’s design of design objects and decorative arts. The article presents the general and specific in the visual arts and technologies of Fedoskino, Palekh, Kholuy and Mstera. It has been determined that Fedoskino has the artistic features of realistic oil painting, and Palekh, Kholui and Mstera, formed on the basis of icon painting, acquired the features of conventionally decorative painting with tempera paints. The article lists the specific artistic features of each of the declared crafts of lacquer miniatures. The authors come to the conclusion that the original Russian traditions of folk painting have recognizable traditions that have developed over decades, which may represent an “artistic code” of Russian culture. Using the wealth of artistic expressiveness of lacquer miniatures in our country, the opportunity has been formed to create modern works of art with decoding the source of inspiration in the process of designing new products of design and applied creativity.

Botticelli-style tempera portrait on tile: Imaging and specific on-site spectroscopic analysis and cleaning examination

In this work, a tempera painting of uncertain attribution from the Uffizi Galleries was studied. The painting, which portraits a man with apparently Botticellian features, was probably created by one of the most skilled forgers of the early 20th century, Umberto Giunti. He used a flat tile as a support, covered with preparatory layers emulating a wall painting. To shed light on the authorship of the painting, it was crucial to investigate its composing materials, as well as the execution technique and the state of conservation. To this end, non-invasive spectroscopic and imaging optical techniques were applied. Specifically, VIS-NIR multispectral reflectography was used to reveal the presence of possible preparatory drawings, pentimenti and overpaintings. Raman and Fibre Optics Reflectance Spectroscopies allowed identifying the pigments used by the artist. Finally, colour variations due to the cleaning procedure were documented in order to provide a support for an informed restoration process.

Capabilities of surface enhanced Raman spectroscopy for the identification of multiple pigments in a complex organic mixture

We proposed a method for identifying the composition of paints used in painting using the method of Surface Enhanced Raman Spectroscopy using signal-amplifying substrates with an array of vertically standing silver nanowires. Using the example of a model tempera paint based on egg white with an inorganic pigment (red lead, massicot, emerald green), it is shown that with a decrease in the concentration of pigment, the use of substrates can significantly increase the sensitivity when detecting pigment in a lower concentration up to 0.01 g, compared with the signal of Raman scattering of light on foil. The use of reinforcing substrates makes it possible to increase the sensitivity of the method, so that it is possible to accurately identify the components used not only individually, but also as a mixture.

Defect detection: An improved YOLOX network applied to a replica of “The Birth of Venus” by Botticelli

Early defects in artworks, which are unnoticeable by the naked eye, can evolve in severity if left unattended; therefore, their timely and accurate detection is of vital importance. Infrared-based non-destructive testing (NDT) methods are widely seen as an effective means to detect defects in artworks. However, most existing methods still rely on the human-based judgment of defects after processing the thermal images, which would inevitably lead to opinion bias and inconsistency. Deep-learning algorithms for computer vision are thought adequate to address the situation. On this point, an improved YOLOX algorithm, with the convolutional block attention module (CBAM) mechanism added to the network, is employed to improve the status quo. The method works with thermal imaging data under flash lamps for tempera paintings on canvas. A part of the famous “The Birth of Venus” by Botticelli (∼1485 ca.) was reproduced by a professional restorer, and three different defects were artificially introduced. To overcome the challenge pertaining to having too few defect samples, the dataset is expanded using finite-element simulation methods. The simulated data are used for training, whereas the replica is used for testing. Experimental results show that adding the CBAM mechanism after upsampling and downsampling of the path aggregation network can maximize network performance. The performance of the improved network herein proposed outperforms the benchmarks, with an average accuracy of 96.67%, a detection speed of 20.0 fps, and a total of 5.08 million parameters.

KNOWLEDGE AND DOCUMENTATION OF RENAISSANCE WORKS OF ART: THE REPLICA OF THE “ANNUNCIATION” BY BEATO ANGELICO

Abstract. The Annunciation by Guido di Pietro from Mugello, known as Beato Angelico, is a wide tempera painting with some fine gold foil placed on a wooden support, today hosted at the Museum of the Basilica of Santa Maria delle Grazie, in San Giovanni Valdarno. On the occasion of the exhibition “Masaccio e Angelico. Dialogo sulla verità nella pittura”, the museum asked to the Department of Architecture at the University of Bologna to develop a digital high-resolution surrogate to favour deep investigations, to plan restoration and to simply tell the stories behind the artwork. Two tasks were accomplished: to let visitors discover the secrets in the painting and to let scholars study the artwork, to better understand the masterpiece. This paper introduces the outcomes of the research developed to digitize the Annunciation, following a dedicated pipeline developed to improve the fruition of its digital replica, originated from different input sources, and surrogating the user experience on the real object. This work presents a method for the 3D reconstruction of the surfaces based on different techniques for elements with different depth resolutions (i.e., the painting and the wooden frame) which combine photogrammetry and photometric stereo exploiting both procedures and pushing forward the boundaries of Gigapixel Imaging and photogrammetric-based 3D model representation.

Evaluation of chia and flax mucilages as consolidants of paint films and as hydrogels used in the cleaning of canvases reverses: first results

In the field of conservation of cultural heritage, animal glues, synthetic resins, and some polysaccharides are used to consolidate pictorial layers. Meanwhile, in order to clean the obverse and the reverse of paintings, organic solvents and aqueous systems are sometimes employed in the form of gels. In this work, vegetable mucilages have been tested for both applications. This research has been carried out in several phases. Firstly, mucilages were extracted from flax and chia seeds. The efficacy of the obtained products was tested on two kinds of mock-ups. As consolidantes, the mucilages were applied on a board with a film of powdery tempera painting. In the case of their use as cleaning gels, two linen cloths were prepared: one with animal glue and the other with gacha, an adhesive used in the Mediterranean Basin. In the last step, the efficacy and safety of the treatments were determined through microscopic observations and FTIR-ATR measurements. Colour and gloss characterisation were also performed in the consolidated pictorial layers. According to the first results shown in this work, flax mucilage can consolidate disintegrated layers of rabbit-skin glue tempera producing minimum colour and gloss changes, whereas chia mucilage has less efficacy to consolidate the tempera. Regarding the efficacy of mucilages as hydrogels, both have shown promising results. With these first results, future work will focus on the study of the long-term behaviour of vegetable mucilages through accelerated artificial ageing and on laying the foundations for their use in other conservation treatments, such as the cleaning of pictorial layers.

On the way to tempera grassa: Unraveling the properties of emulsion-based paint binders

Painting technique in Europe underwent a major change in the 15th century, when the use of egg yolk as a binder in tempera painting was gradually replaced by oil paint. This transitional period probably saw the occasional use of a mixed technique called tempera grassa, in which both types of binders, egg and oil, are mixed in the form of an emulsion. In order to better understand and document this historical painting practice, this article describes the physico-chemical aspects of emulsion-based binders, prepared with egg yolk and either raw linseed oil, or linseed oil partially saponified with lead oxide. Highly stable direct emulsions can be prepared with linseed oil (raw or lead-treated) and egg yolk. Remarkably, lead-treated oil also allows the formation of stable inverse emulsions. The rheological properties of direct emulsions are driven by the oil fraction: as this parameter increases from 0 to 70 wt% oil, the emulsion changes from a viscous liquid to a viscoelastic solid, which allows its flow to be easily tuned by the painter. The impact of egg yolk on the drying mechanism of the emulsion is elucidated thanks to the combined use of NMR relaxometry and FTIR spectroscopy.

Kaluga icon painting: on the issue of the integrity and boundaries of the artistic phenomenon

As the title implies, the article provides a general overview of the Kaluga iconography as a unique regional iconographic tradition that formed in the 2nd half of the 18th century. The primary parameters of this phenomenon are identified, including technological, iconographic, and stylistic factors. Based of archival data and historical evidence, Kaluga’ icons are defined a number of monuments executed in the technique of tempera painting in a specific stylistic manner, for the most part inheriting of artistic direction named “zhivopodobie”. The main iconographic features of the products of the Kaluga icon painters are revealed, in particular, the iconographic renderings of Christ the Almighty and the Mother of God "The Life-Giving Spring" common in Kaluga. It also provides a classification of the main stylistic lines in the Kaluga icon painting, which took shape at the end of the 18th century. The question of the chronological boundaries of the phenomenon is considered. Based on the analysis undertaken, Kaluga iconography is determined to be a full-fledged center of regional icon painting that forms part of a broader context of late iconography. On the one hand, Kaluga's iconography aligns with general trends, with its unique writing style appearing in the last quarter of the eighteenth century, overtly influenced by significant European styles, and experiencing artistic decline in the second half of the nineteenth century. On the other hand, the Kaluga iconography distinguishes itself through its singular stylistic and iconographic peculiarities, sufficient to demarcate it as a distinct artistic center.

SO2-Induced Aging of Hematite- and Cinnabar-Based Tempera Paint Mock-Ups: Influence of Binder Type/Pigment Size and Composition

Hematite- and cinnabar-based paint mock-ups prepared with either rabbit glue or egg yolk binder were artificially aged in an SO2-rich atmosphere, as a model system for investigating the deterioration of tempera paints exposed to an industrial atmosphere. The overall research aim was to identify the type of degradation occurring in tempera paints and the different alteration mechanisms related to the physical, mineralogical and chemical characteristics of the paint. Tempera mock-ups were prepared by mixing binder (egg yolk or rabbit glue) and pigment (cinnabar of different particle sizes or hematite) and were then exposed to SO2 for 2 months in accelerated aging tests. The colour, gloss, reflectance, roughness and micro-texture of the surfaces of the mock-ups were determined before and after the tests. In addition, chemical and mineralogical changes were determined by X-ray Powder Diffraction (XRPD), Attenuated Total Reflection-Fourier Transform Infrared spectroscopy (ATR-FTIR) and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS) analysis. Colorimetric changes were confirmed, mainly in the cinnabar-based paints containing egg yolk, and in the hematite-based paints containing rabbit glue. Neoformed mineral phases have not been detected by XRPD, but precipitation of gypsum on the exposed surfaces has been confirmed by SEM. For cinnabar-based paints, the amount of sulfate-rich deposits was higher on egg yolk mock-ups than on rabbit glue samples, though the opposite was observed for the hematite-based paints. This confirmed the influence of the binder composition and pigment-binder tandem in the susceptibility to SO2 deposition. Pigment particle size did not have a clear influence on the physical and chemical changes in the tempera mock-ups during the ageing tests.

Novel integration of non-invasive imaging techniques for the analysis of an egg tempera painting by Pietro Lorenzetti

The identification of an artist's palette through the application of non-invasive techniques is a challenging goal due to the huge variety of artistic materials that constitutes a painting. An effective approach is to combine several techniques providing complementary information in order to minimise the risk of misinterpreting the data. In this paper, we propose a multi-analytical method comprising three non-invasive mapping techniques, namely Reflectance Imaging Spectroscopy (RIS), Macro-X-Ray Fluorescence (MA-XRF) and Fluorescence Lifetime Imaging (FLI), for the study of a fourteenth-century painting by Pietro Lorenzetti from the Uffizi Gallery collection. For the low-cost and time-saving interpretation and integration of the data provided by the different techniques, a purposely developed software for multivariate statistical analysis was used. FLI data were acquired with a prototype applied for the first time on a work of art, and the data were processed with a method based on phasor analysis. The information obtained was discussed within a multidisciplinary team of experts on painting materials and data processing belonging to both the scientific and the conservation community.

Andrei Negura and transposition of emotions into color

The present approach represents the vision of a historian on the evolution and development of decorative art in Moldova through the lens of the creation of Andrei Negură, an artist who asserted himself equally in painting and tapestry. He made a sensation at the beginning of his activity in the 1980s with the tapestries he exhibited, shaping a new attitude of society, driving his interest in this genre of decorative arts. His creation, deeply rooted in the aesthetics of traditional weaving, offers outstanding samples of modern art, products of original plastic and technological experiments. Thanks to him, for the first time tapestry began to be studied at the level of a higher education institution, he founded the Department of Textile Arts at the Academy of Music, Theater and Fine Arts, the “Tapestry” specialty. His last personal exhibition, Revelations in Color, at the “Constantin Brâncusi” Exhibition Center in Chisinau, presents him in the fullness of his talent as an author of parietal tapestry, three-dimensional tapestry, easel and applicative graphics, oil painting and tempera painting. Through his complex creation, A. Negură made a significant contribution to the valorization of the national cultural heritage.

The Application of Chitosan for Protection of Cultural Heritage Objects of the 15-16th Centuries in the State Tretyakov Gallery.

Microorganisms are one of the main factors in the deterioration of cultural heritage, in particular art paintings. The antiseptics currently used in painting have significant limitations due to insufficient effectiveness or increased toxicity and interaction with art materials. In this regard, the actual challenge is the search for novel materials that effectively work against microorganisms in the composition with painting materials and do not change their properties. Chitosan has pronounced antimicrobial properties but was not used previously as an antiseptic for paintings. In our study we developed a number of mock layers based on sturgeon glue, supplemented which chitosan (molecular weight 25 kDa or 45 kDa), standard antiseptics for paintings (positive controls) or without additives (negative control). According to Fourier transform infrared spectroscopy and atomic force microscopy, the addition of chitosan did not significantly affect the optical and surface properties of this material. The ability of chitosan to effectively protect paintings was shown after inoculation on the created mock-up layers of 10 fungi-destructors of tempera painting, previously isolated from cultural heritage of the of the 15-16th centuries in the State Tretyakov Gallery, on the created mock layers. Our study demonstrated the principled opportunity of using chitosan in the composition of painting materials to prevent biodeterioration for the first time.

Biotransformation of Androstenedione by Filamentous Fungi Isolated from Cultural Heritage Sites in the State Tretyakov Gallery.

Simple SummaryMicroorganisms are able to grow on substrates of the most diverse nature. One of the most practical habitats, in terms of cultural heritage conservation, is fine art objects such as tempera or oil paintings on canvas. Since tempera paints are produced on the basis of egg yolk, which is one of the richest sources of cholesterol in nature (up to 2% of dry weight), and in the process of aging of tempera materials, changes in cholesterol do not affect the core structure of the steroid nucleus, the group of fungi that we have isolated are tempera painting destructors is seen as a promising object for screening for their possible steroid-transforming activities. In this regard, the purpose of our work was to determine the ability to transform pharmaceutically significant steroids with dominant fungi-destructors of tempera paintings, previously isolated in the State Tretyakov Gallery. Consequently, we have demonstrated for the first time that fungi-destructors of tempera paintings have steroid-transforming activity and are promising microorganisms for screening for biotechnologically significant transformations of steroids with further industrial use.The transformation of steroids by microorganisms is widely used in medical biotechnology. A huge group of filamentous fungi is one of the most promising taxa for screening new biocatalytic reactions in order to obtain pharmaceutically significant steroids. In this work, we screened 10 filamentous fungi-destructors of egg tempera for the ability to biotransform androst-4-en-3,17-dione (AD) during cultivation in a liquid nutrient medium or in a buffer solution. These taxonomically unrelated strains, belonging to the classes Eurotiomycetes, Dothideomycetes and Sordariomycetes, are dominant representatives of the microbiome from halls where works of tempera painting are stored in the State Tretyakov Gallery (STG, Moscow, Russia). Since the binder of tempera paints, egg yolk, contains about 2% cholesterol, these degrading fungi appear to be a promising group for screening for steroid converting activity. It turned out that all the studied fungi-destructors are able to transform AD. Some strains showed transformation efficiency close to the industrial strain Curvularia lunata RNCIM F-981. In total, 33 steroids formed during the transformation of AD were characterized, for 19 of them the structure was established by gas chromatography/mass spectrometry analysis. In this work, we have shown for the first time that fungi-destructors of tempera paintings can efficiently transform steroids.

A multidisciplinary study of biodeteriorated Celje Ceiling, a tempera painting on canvas

Interdisciplinary investigations of damaged cultural heritage objects have nowadays become standard practise. Numerous techniques in various fields may generate large amounts of data, difficult to interpret. Machine learning was applied to data collected from samples of a painting to build a predictive model of potential further biodeterioration and consequent damage to the paintings. We used this strategy for a deteriorated 17th century Celje Ceiling, tempera painting in a wooden frame, covering 143 m2 of the ceiling. An interdisciplinary approach, from monitoring microclimatic conditions and wood moisture content, to examinations using UV and VIS photography, analyses of paint layers and decay products by Raman and FTIR spectroscopy, SEM-EDS, and protein binders by ELISA, was used to assess current condition of the painting. Data from 535 painting's samples were subjected to analysis by machine learning methods. Moulding, the main cause of biodeterioration, was found to be strongly influenced by the position of the painting in the room and related microclimatic conditions. The presence of a coating layer, protein binders and pigments, such as goethite, ultramarine and kaolinite, had important role in mould development as well. The painting was mainly damaged by currently non-active, presumably xerophilic Aspergillus species, as determined by microscopy, cultivation and amplicon sequencing.

Pagan Otherness in the Christian Church Iconography of Ancient Philosophers and Intellectuals in Russia and the Balkans

The Russian Orthodox iconography of ancient philosophers and thinkers has long attracted Western and Russian researchers. Greek and Roman philosophers depicted in Russian churches and in other visual sources have almost nothing in common with real historical philosophers: their images were based on Byzantine Apocrypha, in which philosophers were presented as righteous pagans, proclaiming the coming of Christ long before his birth. The author introduces for the first time three new sources, two of which - tempera paintings from the 18th century with Hermes and Aphrodite, and frescoes from the 17th century carved from the walls of the Moscow Novospassky monastery with images of Aristotle, Solon, Plutarch, and Anacharsis - are kept in the State Historical Museum in Moscow, and another illustrated 17th-century collection of aphorisms of the Hellenic sages named Melissa, is in the collections of the Russian National Library in St Petersburg. The author establishes a typology of all the ancient philosophers (as they were called in sources) found in Russian Orthodox iconography, dividing them into four groups: historical philosophers, historical intellectuals, sibyls, and gods. Thereafter, the text analyses the meaning of visual markers of Otherness that are present in all samples of the studied array of iconography. It is assumed that the meaning of such visual markers was that they showed the viewer the Hellenic sages as the Other. Ancient philosophers and intellectuals were presented as pagans from the East, since it was necessary to visually separate them from the real saints recognized by the Orthodox Church. Even though all of them were credited with prophecies about the rise of Christianity, the primary role of the above attributes was the visual differentiation of pagan philosophers from Orthodox saints.