An analytical and applicative approach to the cleaning of artworks

Cleaning is a critical operation aimed to recovering the legibility of the artwork (1963, C. Brandi, Theory of restoration), and it may involve, depending on the instances, removing soiling materials from surfaces (surface cleaning) or thinning/removing altered or unwanted layers (discoloured varnishes, overpaints, patinas,etc..). It should be performed in the most selectively possible way, minimizing the risk of altering the chemical-physical and morphological properties of the surfaces to be preserved. Aims of the present research were to develop and to evaluate specific materials and selective methodologies for the surface cleaning of plaster and wax artworks. Another purpose was to investigate the risk associated with the exposure of egg yolk-based tempera films to water and organic solvents during cleaning. In collaboration with several Institutions, relying on the indispensable collaboration of various conservators/restorers, an analytical and applicative research was conducted on both mocks up and actual artworks or their fragments. This research allowed to develop an effective and innovative method for cleaning plaster by using Agarose-based gelling materials, to prove the suitability of specifically designed aqueous solutions for cleaning wax artworks, and to evaluate the behaviour and the effects of water and organic solvents on unaged egg tempera films and on a 16th century actual panel painting, yielding information on physical phenomena such as visual changes and swelling/leaching processes at various solvent polarities.La pulitura è un’operazione critica finalizzata a ripristinare la leggibilità dell’opera d’arte (1963, C. Brandi, Teoria del Restauro) che consiste, a seconda dei casi, nella rimozione di materiale superficiale di deposito (surface cleaning) o nell’alleggerimento/rimozione di sostanze filmogene alterate o non volute (vernici ossidate e alterate cromaticamente, ridipinture, patine ecc..). Essa è un’operazione selettiva, che deve essere condotta minimizzando il rischio di alterazione chimico-fisica e delle proprietà morfologiche delle superfici da preservare. Questa ricerca aveva lo scopo di sviluppare e valutare specifici materiali e metodologie selettive per la surface cleaning di opere in gesso e in cera e di studiare il rischio associato all’uso di acqua e solventi organici durante la pulitura di film di tempera all’uovo intero. In collaborazione con varie Istituzioni e con l’indispensabile supporto di conservatori/restauratori, è stata condotta una ricerca con un approccio analitico e applicativo, sia su campioni di laboratorio che su opere d’arte o loro frammenti. Questa ricerca ha permesso di sviluppare un innovativo ed efficace metodo di surface cleaning per i manufatti in gesso con l’uso di gel a base di Agarosio, ha verificato l’idoneità di specifiche soluzioni acquose per la surface cleaning di manufatti in cera ed infine ha valutato il comportamento e gli effetti dell’acqua e di solventi organici su film di tempere giovani e su una tempera su tavola del XVI secolo, ricavando informazioni su fenomeni fisici come cambiamenti ottici e fenomeni di rigonfiamento/leaching a diverse polarità dei solventi utilizzati

Assessing the (In)Stability of Urban Art Paints: From Real Case Studies to Laboratory Investigations of Degradation Processes and Preservation Possibilities

Urban art as a shared expression of street art between artists, citizenship and municipalities has always had an important role in the social life and appearance of modern cities. However, the durability of urban and street artworks is susceptible to the degradation processes that the employed commercial paint formulations undergo once outdoors. These are complex mixtures of compounds, differently sensitive to environmental agents according to their chemical nature. Starting from the colorimetric analysis of murals created in 2010, 2011 and 2018 in Reggio Emilia, Italy, documenting their degradation already after a few months, this study aimed at understanding the stability of the most unstable paints used by the artists in these artworks. A multi-analytical approach evaluated the commercial products under the chemical point of view, after natural and accelerated ageing. Additionally, two manufactured anti-UV varnishes were evaluated for their possible use as coatings. The results pinpointed the weaknesses of the selected paints and highlighted how the application of an anti-UV coating might slightly affect the visual aspect of the artwork, though ensuring a greater resistance to the outdoor conditions due to their minor chemical sensitivity to environmental agents

An in-and-out-the-lab Raman spectroscopy study on street art murals from Reggio Emilia in Italy

The street art murals ‘The Big Mother’ by Gola Hundun, the ‘Big Sacral Bird’ by Kenor, the ‘Oriental Carpet” by H101 and “The Economy Subdues You” by Zosen, belonging to the Cooperative Popular Houses of Mancasale and Coviolo in Reggio Emilia (Italy), were investigated by the use of various mobile Raman spectrometers coupled to different lasers and by micro-Raman spectroscopy on selected samples. The study was made necessary by the evident fading of many colours, despite the young age of the paintings, realized in 2010. The first step of the investigation, realized by the on-site campaign, was the identification of the materials, and in particular of the dyes. The main chromophores were identified as polycyclic, monoazo- and disazo- organic pigments, with inorganic compounds as bismuth vanadate (BiVO4) together with the extensive presence of rutile (TiO2). The second step was devoted to the study of the degradation mechanism affecting the colourful layers of the murals. It required the use of laboratory micro-spectrometers and was carried out on a reduced set of samples, selected during the in-situ campaign. This combination of on-site and laboratory Raman spectroscopy allowed the obtaining of the complete identification of the palette used by the different artists in a single day of measurements, in a complete non-destructive day. In addition, it was possible to minimize the number of samples required for the study of the degradation process. Graphical abstract: [Figure not available: see fulltext.

Il caso dell'Erbario Casapini (secolo XVIII)

Casapini's Herbarium is an 18th century manuscript, belonging to the Palatina Library in Parma and currently stored at the Botanical Garden of Parma University. The Herbarium collects nearly 200 samples of dried plant specimens that have been severely affected by physical, biological and chemical degradation. In 2016 the Inner Wheel Club Italia-Parma Est, an international female association, decided to fund the conservation of this Herbarium in order to preserve it and allow its study. A large team of professionals, including conservators, chemists, physicists and a botanist, has been working on the project to secure this unique but very fragile object. This paper discusses the condition assessment, the identification of degradation processes and the first conservation approach to the Casapini Herbarium. Issues related to the treatment of heavily corroded areas, the resewing of the sections and the future storage of the manuscript are also identified and highlighted for further research

Lorenzo Lotto's painting materials: an integrated diagnostic approach

This paper presents the results of a comprehensive diagnostic investigation carried out on five paintings (three wood panels and two paintings on canvas) by Lorenzo Lotto, one of the most significant artists of the Italian Renaissance in the first half of 16th century. The paintings considered belong to 1508-1522 period, corresponding to the most significant years of Lotto's evolution. A wide array of non-invasive (reflectance spectrometry and Xray fluorescence) and micro-invasive analytical techniques (optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, micro-FTIR spectroscopy, micro-Raman spectroscopy, gas chromatography coupled with mass spectrometry and high performance liquid chromatography coupled with photodiode array detection and mass spectrometry) were applied in order to provide a large set of significant data, limiting as much as possible the sampling. This study has proved that Lotto's painting palette was typical of Venetian practice of that period, but some significant peculiarities emerged: the use of two kinds of red lakes, the addition of calcium carbonate and colourless powdered glass, the latter frequently found in pictorial and ground layers. Moreover, the integrated investigation showed that Lotto's technique was sometimes characterized by the use of coloured priming and multi-layer sequences with complex mixtures. Chromatographic analyses allowed to identify in all specimens: azelaic, palmitic and stearic acids, generally referring to the presence of drying oils. The extension of additional non-invasive examination to about 50 paintings by the same author, spanning from 1505 to around 1556, helped to verify the evolution in the use of some pigments, such as the yellow ones, where Pb-Sb yellow was used alongside Pb-Sn yellow. (C) 2016 Elsevier B.V. All rights reserved