Non-Invasive-Monitoring Methodology for the Evaluation of Environmental Impacts on Istrian Stone Surfaces in Venice

This work proposes a non-invasive, affordable, and easily reproducible methodology for monitoring limestone surfaces vulnerability. The proposed methodology integrates the study of environmental factors impacting limestone surfaces with physical–chemical and morphological observations of historical Istria stone surfaces in Venice. Pollutant trends of particulate matters (PPM), NO2, SO2, O3, and the meteorological forcing were considered over a 20-year period. To collect information on the conservation state of stone surfaces, visual, optical microscopy observation, chemical analysis via FT-IR-ATR spectroscopy, and the evaluation of morphological and profilometric parameters by digitalizing the surface of silicone molds were carried out. The surfaces of Ca’ Foscari, Ca’ Dolfin, and Garzoni Palace were monitored in 2015 and five years after. Indicators, such as site, sheltered or exposed position, and location of the stone surfaces, were taken into consideration for data interpretation. A relationship between surface conservation state and the proposed environmental indicators has been evaluated. Deposits and crusts were found only in the courtyard façade and in sheltered points, reflecting SO2 reduction; large, eroded areas were found on exposed surfaces related to rain runoff and possibly related to the locally high NOx levels

A preliminary evaluation of chemical interaction between sanitizing products and silk

The ongoing Coronavirus crisis involved almost all sectors as well as museums, collections, and historical sites all over the world. Even though artworks do not have the ability to spread the virus, the pandemic officially introduced in cultural sites alcohol-based products (even by visitors for personal use) as these products were indicated to be able to inactivate the virus and were imposed by many local authorities. In this context, the need to conciliate the safety of the visitors and the protection of artworks represents a challenging task. The possibility that accumulation of vapour coming from the sanitizing solutions or from accidental spills, potentially caused also by visitors, should be considered. The study focuses specifically on the possible interactions between sanitizing alcohol-based products and silk, since this material is present in many cultural sites all over the world on upholsteries and tapestries. The recommended sanitising solution (75% ethanol, 20% water, 5% benzalkonium chloride) selected by the Italian Ministry for Cultural Heritage (MIBACT) was considered. Pure distilled water, absolute ethanol and water/ethanol blends in different concentrations were also tested. Chemical and morphological variations on the silk have been evaluated with Scanning Electron Microscopy - SEM, Atomic Force Microscopy - AFM and portable instruments (contact microscope, colorimeter, Infrared and Raman spectroscopy). IR and Raman analyses did not detect significant chemical changes in silk. However, Raman spectra showed, after immersion treatments, minor variations in the intensity of peaks attributed to dyes. Residues of benzalkonium chloride after immersion tests in sanitising solution are present, confirmed also by SEM and AFM analyses. Even if chemical spectroscopic changes were not relevant, the colour of few samples seemed to consistently fade after immersion treatments, thus affecting the visual appearance of textiles.The ongoing Coronavirus crisis involved almost all sectors as well as museums, collections, and historical sites all over the world. Even though artworks do not have the ability to spread the virus, the pandemic officially introduced in cultural sites alcohol-based products (even by visitors for personal use) as these products were indicated to be able to inactivate the virus and were imposed by many local authorities. In this context, the need to conciliate the safety of the visitors and the protection of artworks represents a challenging task. The possibility that accumulation of vapour coming from the sanitizing solutions or from accidental spills, potentially caused also by visitors, should be considered. The study focuses specifically on the possible interactions between sanitizing alcohol-based products and silk, since this material is present in many cultural sites all over the world on upholsteries and tapestries. The recommended sanitising solution (75% ethanol, 20% water, 5% benzalkonium chloride) selected by the Italian Ministry for Cultural Heritage (MIBACT) was considered. Pure distilled water, absolute ethanol and water/ethanol blends in different concentrations were also tested. Chemical and morphological variations on the silk have been evaluated with Scanning Electron Microscopy - SEM, Atomic Force Microscopy - AFM and portable instruments (contact microscope, colorimeter, Infrared and Raman spectroscopy). IR and Raman analyses did not detect significant chemical changes in silk. However, Raman spectra showed, after immersion treatments, minor variations in the intensity of peaks attributed to dyes. Residues of benzalkonium chloride after immersion tests in sanitising solution are present, confirmed also by SEM and AFM analyses. Even if chemical spectroscopic changes were not relevant, the colour of few samples seemed to consistently fade after immersion treatments, thus affecting the visual appearance of textiles

Accelerated Ageing Procedures to Assess the Stability of an Unconventional Acrylic-Wax Polymeric Emulsion for Contemporary Art

This research evaluates the stability of an aqueous emulsion of acrylic copolymers and waxes. Edelwachs, generally applied on wood, has been recently used as an unconventional medium in contemporary painting. Through Pyrolysis–Gas Chromatography–Mass Spectrometry (Py-GC-MS) and Fourier Transformed Infrared Attenuated Total Reflectance (FT-IR-ATR) analyses, the composition of Edelwachs was defined as a mixture of acrylic polymers (MA, MMA, nBA, nBMA), Carnauba and microcrystalline waxes and additives. Mock-ups-obtained mixing Edelwachs with titanium white, zinc white and ultramarine blue were subjected to UV, high temperatures, and high relative humidity accelerated ageing. The effect of the ageing procedures was evaluated through optical microscopy, colourimetric measurements, FT-IR-ATR, Thermogravimetry and Differential Scanning Calorimetry (TG-DSC) and wettability measures. FT-IR-ATR spectra do not show significant variations in terms of chemical stability, indicating a fair stability of Edelwachs as a painting binder. UV and high temperature treatments show the most relevant effects in terms of colorimetric changes (increasing of b*) and thermal stability. The TG-DSC highlights the influence of the pigments (specifically zinc white) mainly on the thermal behaviour of the acrylates. The unexpected decrease of wettability of the paint films, registered after ageing, may indicate a possible phase separation among acrylates and waxes.This research evaluates the stability of an aqueous emulsion of acrylic copolymers and waxes. Edelwachs, generally applied on wood, has been recently used as an unconventional medium in contemporary painting. Through Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC-MS) and Fourier Transformed Infrared Attenuated Total Reflectance (FT-IR-ATR) analyses, the composition of Edelwachs was defined as a mixture of acrylic polymers (MA, MMA, nBA, nBMA), Carnauba and microcrystalline waxes and additives. Mock-ups-obtained mixing Edelwachs with titanium white, zinc white and ultramarine blue were subjected to UV, high temperatures, and high relative humidity accelerated ageing. The effect of the ageing procedures was evaluated through optical microscopy, colourimetric measurements, FT-IR-ATR, Thermogravimetry and Differential Scanning Calorimetry (TG-DSC) and wettability measures. FT-IR-ATR spectra do not show significant variations in terms of chemical stability, indicating a fair stability of Edelwachs as a painting binder. UV and high temperature treatments show the most relevant effects in terms of colorimetric changes (increasing of b*) and thermal stability. The TG-DSC highlights the influence of the pigments (specifically zinc white) mainly on the thermal behaviour of the acrylates. The unexpected decrease of wettability of the paint films, registered after ageing, may indicate a possible phase separation among acrylates and waxes

A Critical Review on the Analysis of Metal Soaps in Oil Paintings

Up to 70 % of the oil paintings conserved in collections present metal soaps, which result from the chemical reaction between metal ions present in the painted layers and free fatty acids from the lipidic binders. In recent decades, conservators and conservation scientists have been systematically identifying various and frequent conservation problems that can be linked to the formation of metal soaps. It is also increasingly recognized that metal soap formation may not compromise the integrity of paint so there is a need for careful assessment of the implications of metal soaps for conservation. This review aims to critically assess scientific literature related to commonly adopted analytical techniques for the analysis of metal soaps in oil paintings. A comparison of different analytical methods is provided, highlighting advantages associated with each, as well as limitations identified through the analysis of reference materials and applications to the analysis of samples from historical paintings

Non-Vascular Ceramic Sherds Coming from Two Italian Etruscan Settlements: Peculiarities and Interpretation of Their Possible Use

Peculiar non-vascular ceramic slabs of uncertain use were found in two different Etruscan settlements of the Po Delta region (San Basilio di Ariano nel Polesine and Adria, North-East Italy) dated back to the first millennium BC. Different interpretations concerning the primary role of these fragments have been suggested by previous scholars. To bring to light an understanding of the construction processes that appear to be unique to the San Basilio and Adria settlements, a multi-analytical approach has been carried out. Macroscopic observations enabled these materials to be preliminary subdivided into groups based on chromatic features, followed by the identification of their chemical composition through FTIR-ATR spectroscopy. Moreover, the open porosity was estimated by the total water absorption test, and the superficial morphology and elemental composition of specific samples were analyzed using SEM-EDS. Furthermore, the firing temperature of a few selected fragments was evaluated by the TGA-DSC technique in order to investigate ancient production techniques. The results of the research lead us to consider the role of these peculiar non-vascular ceramic slabs as building materials due to their specific protective properties, considering the environmental conditions of the Po Delta region

Evaluating the Impacts of Alcohol-Based Solutions on Silk: Chemical, Mechanical and Wettability Changes before and after Artificial Ageing

Due to the COVID-19 pandemic, since 2020, alcohol-based sanitisers have been frequently used in museums and historic sites. Although they provide a safer environment for visitors, the impact of the (components in) sanitisers on the cultural heritage on open display is still uncertain. The current study investigated the effects of ethanol and isopropanol solutions on silk artefacts specifically in relation to possible mechanical changes and to their long-term impact based on artificial ageing. Thus, samples from three modern silk fabrics were treated through spraying and immersion with six solutions, two of which contained benzalkonium chloride (BZK), a surfactant suggested by Italian national guidelines in the formulation of sanitisers for museums. The impact of the treatment was studied from a chemical perspective, i.e., through spectroscopic techniques, and considering changes in the mechanical strength through uniaxial tensile testing. In addition, water wettability was measured. To study whether the contact with the solutions can affect the degradation path of silk, after the treatment, samples were exposed to light ageing and were stored at medium and high RH, i.e., 55% and 80%. Furthermore, treated and untreated silk textiles were placed in the Museum of Palazzo Mocenigo (Venice) to define the behaviour in an actual museum environment. The results show that, even when silk is immersed in the solutions for 180 min, no relevant chemical and physical changes can be observed on silk fibres. Variations noted at the end of the light ageing occurred regardless of the treatments with the solutions, so they are not affected by the contact with sanitisers. Nevertheless, when treating the samples (also through spraying) with solutions containing BZK, the surfactant is adsorbed by the textile. Once adsorbed, BZK significantly increases the water wettability of silk, causing a persistent modification of the property as also observed at the end of the ageing and in situ tests

Treatment of stone surfaces in Venice. Some study cases

[EN] This comparative study of the stone surfaces of three Venetian buildings, Sansovino’s Library, Corner Palace and Foscari Arch, is both interesting and original, since it shows that blackened surfaces do not necessarily mean the presence of deterioration phenomena such as black crust and sedimentation, but often correspond to intentional patinas applied in order to protect the stone or in colour matching treatments practised during subsequent works. The article makes a double contribution to the culture of conservation: the existence a tradition of protection and conservation treatments on stone walls and the current need to conserve these intentional patinas.[ES] Este estudio comparado de las superficies pétreas de tres edificios venecianos, la Biblioteca de Sansovino, el Palacio Corner y el Arco Foscari, reúne interés y novedad ya que demuestra que las superficies ennegrecidas no sólo representan la presencia de fenómenos de degradación como costra negra y depósitos sino que, a menudo, corresponden a patinados intencionales aplicados para proteger la piedra o tratamientos de entonación del color realizados en posteriores intervenciones. El artículo supone una doble aportación a la cultura de la conservación: la existencia de una tradición de los tratamientos de protección y conservación de los paramentos de piedra y la necesidad actual de conservar la presencia de estos patinados intencionales.Quendolo, A.; Zendri, E.; Biscontin, G. (2003). El tratamiento de las superficies pétreas en Venecia. Algunos casos de estudio. Loggia, Arquitectura & Restauración. (14-15):74-87. doi:10.4995/loggia.2003.3558SWORD748714-1