“A warning from Mars”: effect of microclimate changes at the Specola Museum of Palermo

The Specola Museum is located at the Palermo Astronomical Observatory and preserves most of its material heritage. It is part of the Museum System of the University of Palermo (SiMuA) and its management and conservation are entrusted to the INAF - Astronomical Observatory of Palermo. Among the historical instruments on display, there is a 19th-century painted wooden globe reproducing the surface of Mars. It has been on display in a showcase, inside the Merz Telescope Hall, for about 20 years without undergoing any type of intervention or evident deterioration sign. From 2021, in less than two years, damages of its pictorial layers occurred at a progressive rate. The European Standard EN 15757 explains that hygroscopic materials are highly vulnerable to microclimate changes. The wooden globe was in good conditions after two decades of permanence at the museum, but the recent control and management of the indoor climate was not compatible with the past climate history of the globe to which it has adapted. The speed of the degradation made it evident that the microclimatic conditions of the room changed abruptly. The warning deduced from the Mars globe deterioration was hence easy to decode: there is something wrong with this climate! It is well known that museum microclimate plays a key role in the conservation of the objects on display. It may trigger or aggravate degradation processes of the materials constituting the object exhibited and affect their “life expectancy”. Moreover, each object responses peculiarly to environment variability, depending on its composition and conservation history. When an artifact is composed of different materials, unexpected synergistic effects may develop. Finding appropriate values range of temperature, relative humidity and illuminance and managing them to guarantee the conservation of the entire collection, and at the same time improving the thermal comfort for people working there, is a difficult task. The issue becomes even more challenging in buildings not originally designed for conservation purposes, as the Specola Museum, located in the ancient observatory rooms, built in 1790 on the top of the 12nd-century Royal Palace. An accurate restoration has been made, and conservation measures have been adopted, to stop the serious deteriorating processes affecting the model of Mars but the risk of further deterioration phenomena involving other objects is expected to increase substantially if no actions are taken. This contribution intends to present the results of the preliminary study concerning the thermo-hygrometric records taken in the Merz Telescope Hall over the last two years and propose specific actions to improve its microclimate conditions. References Carotenuto M. R., Randazzo D., Chinnici I., Genua G., Preventive Conservation Projects on LAM Materials at the INAF-Astronomical Observatory of Palermo “G.S. Vaiana”, Bulletin of the AAS, 54(2) (2022) Carotenuto M. R., Chinnici I. et al., Rapporto tecnico INAF 2022 - Il Museo della Specola: progetti per la conservazione, la fruizione, la comunicazione (2018-2020) Camuffo D., Microclimate for cultural heritage. Measurement, Risk Assessment, Conservation, Restoration, and Maintenance of Indoor and Outdoor Monuments, Elsevier, third Edition (2019) Antomarchi C., Pedersoli Jr., Michalski S., Guide to Risk Management, ICCROM (2016) Foderà Serio G., Chinnici I., L'Osservatorio Astronomico di Palermo, Palermo (1997

Moisture Damage in Ancient Masonry: A Multidisciplinary Approach for In Situ Diagnostics

San Nicola in Carcere, one of the minor basilicas in the historical center of Rome, was the location of a wide investigation campaign of the water-related deterioration causes, present in the lower sector of the apse and adjacent pillars, affected by water infiltrations, mould and salt efflorescence. The results obtained identify the presence of water content and related effects mainly on the sides of the apsidal wall. This work focuses on the use of five Non-Destructive Techniques (NDT) and intends to show the gains obtained by integrating widely interdisciplinary methods, namely the Infrared Thermography (IRT), the Unilateral Nuclear Magnetic Resonance (Unilateral NMR), the Acoustic Tomography (AT), the Acoustic Imaging (AI) and the Laser-Induced Fluorescence (LIF). All the techniques contribute to the rapid, non-invasive and early identification of the moisture distribution, while some of them (LIF and AI) also address the determination of some moisture effects. The integrated use of different techniques helps to take the multidisciplinary point of view necessary to formulate an effective restoration intervention based on a sound scientific rationale; nonetheless, it allows to experiment a holistic approach, verifying the potential of a wide range of NDTs available within the context of a restoration yard

La salvaguardia dell'ambiente e del biota nel settore dei beni culturali

In the past the unsuitable choices made when choosing products to be used for conservation actions related to artefacts of historic-artistic interest were mainly due to wrong assessments. More specifically this means: insufficient determination of the structure-aspect relation which characterises the original materials that make up the artefacts; insufficient knowledge of the behaviour of new materials due to natural ageing processes which might impoverish them or deprive them of specific qualities; lack of interest in measuring the medium-long term effects and interactions of the artefacts-products-environment system. The latter is sometimes capable of triggering new and more serious factors leading to the deterioration of the artefact sometimes causing even greater damage. In particular this study refers to the aspects related to the potential danger deriving from products used for the different types of conservation interventions on stone materials

Chapter Pyrgi: analysis of possible climatic effects on a coastal archaeological site

This work refers to an interdisciplinary study on the archaeological site of Pyrgi, an Etruscan harbour still under excavation, located on the Lazio’s coast in Santa Severa, in the province of Rome. The objective of the research is to assess the main cause of the floods and the time the water stays in the site to determine if the floods are periodic phenomena over time or random events for guarantee a correct conservation of the site . The study is based on the combined use of geomatic technologies, meteorological and climatic models, and hydrogeological knowledge

Pyrgi. Analysis of possible climatic effects on a coastal archaeological site

This work refers to an interdisciplinary study on the archaeological site of Pyrgi, an Etruscan harbour still under excavation, located on the Lazio’s coast in Santa Severa, in the province of Rome. The site in question is subject to frequent flooding which compromises its accessibility and delays the archaeological excavation operations. The study is based on the combined use of geomatic technologies, meteorological and climatic models, and hydrogeological knowledge of the examined site, to have a global view of the hazard to which it is exposed. Different geomatic techniques at different scales are used in the analysis. Large scale surveys are carried out to define the water networks and to monitor the site using satellite images. On a small scale, drone photogrammetry techniques are used to assess the morphology of the territory and eventual protection from natural hazards present in the site. Using these images, a detailed digital surface model (DSM) has been generated. The objective of the research is to assess the main cause of the floods and the time the water stays in the site and to determine if the floods are periodic phenomena over time or random events. The study was conducted using images captured by Sentinel 2 satellites processed at level 2-A. These images enabled the identification of the flooding periods of the site for the years of monitoring. The study was conducted by comparing the captured images with rainfall data, paying attention to extreme weather phenomena that occurred from 2012 to date. The rainfall data are provided by the National Department of Civil Protection to CNR-ISAC by an agreement between the two institutions. The same images have been compared with the wind data recorded by the anemometer located in the Civitavecchia harbour and the wave height data available from ERA5 reanalysis. Knowledge of the main cause of the floods and a possible periodicity will allow to plan correct conservation of the site through specific protection measures designed according to the hazards to which it is exposed

Evaluation of pictorial layers ageing by HyperSpectral Imaging

The possibility to perform a full characterization and identification of pigments in pictorial layers represents one of the most challenging targets in the field of cultural heritage, especially if their fulfillment is achieved setting up not invasive and not destructive analytical procedures. In this perspective, HyperSpectral Imaging (HSI) based sensing architectures, acting in the VIS-NIR and SWIR wavelength ranges, can represent an important diagnostic tool to realize the monitoring of paintings, as well as to evaluate their preservation status [1]. The goal of this study is to evaluate the alteration of different pictorial layers, as resulting from the combination of different supports, pigments and binders, according to different irradiation times. Starting from the result of recent studies [2], 6 pigments were thus mixed (i.e. red ocher, yellow ocher, chrome yellow, mineral blue, cobalt green and malachite) with four different binders (i.e. Arabic gum, gouache, egg tempera, and linseed oil), applying them on two different media (i.e. wood and canvas). The resulting samples have been aged in solar box and acquired at different aging times. Surface spectra of each sample were then acquired in VIS-NIR and SWIR ranges. Starting from the collected information (i.e. hypercube) chemometric techniques have been utilized to extract and handle pictorial layers information. The sequential application of Principal Component Analysis (PCA) and Partial Least Square-Discriminant Analysis (PLSDA) was then applied in order to study the pictorial layers spectra variations linked to the effects of the applied aging cycles. The sensing architectures have been designed and implemented, both at hardware and software level, in order to perform both in-situ (i.e. directly where the painting is) and ex-situ (i.e. at laboratory scale) analyses. The results showed as the developed modelling procedure allows to correctly predict sample characteristics and composition. Furthermore, it is objective, rapid and non-destructive. The implementation of such approach could allow to perform a full monitoring of the state of conservation and/or the characterization of materials and/or supports not easy to assess with conventional techniques

IDENTIFICAZIONE DI PIGMENTI IN STRATI PITTORICI MEDIANTE IMPIEGO DI IMAGING IPERSPETTRALE

La possibilità di poter caratterizzare i pigmenti all’interno di uno strato pittorico rappresenta una sfida nello studio dei dipinti, soprattutto mediante l’impiego di tecniche analitiche non distruttive e non invasive. L'utilizzo dell’imaging iperspettrale (HSI) come tecnica diagnostica per l’analisi degli strati pittorici e la valutazione dello stato di conservazione, appare di grande interesse per le sue potenzialità. Tale tecnica di analisi, infatti, è di tipo non distruttivo, non invasivo e, con implementazioni dell’hardware, può diventare portatile. La sua combinazione con tecniche chemiometriche permette di ottenere dati qualitativi e/o quantitativi sulle caratteristiche chimico-fisiche dei materiali investigati. Lo studio in corso [1-4] si pone quale obiettivo quello di valutare le possibilità offerte da un tale approccio analitico per l’identificazione dei pigmenti in strati pittorici. I sistemi iperspettrali impiegati sono ImSpector™ V10E (range spettrale VIS-NIR da 400 a 1000 nm) e SISUCHEMA XL ImSpector™ N25 (range spettrale SWIR da 1000 a 2500 nm). Vengono qui presentati alcuni dei risultati ottenuti dallo studio effettuato sui primi sei pigmenti presi in esame (ocra rossa, ocra gialla, giallo cromo, blu minerale, verde di cobalto e malachite), mescolati con quattro differenti leganti (gomma arabica, guazzo, tempera d’uovo, olio di lino con resine alchidiche) ed applicati su due tipologie di supporto pittorico (legno e tela). I provini di riferimento così realizzati sono stati acquisiti con HSI; i dati ottenuti (ipercubo) sono stati poi elaborati con metodi chemiometrici: Principal Component Analysis (PCA) e Partial Least Square-Discriminant Analysis (PLS-DA), mediante software PLS_Toolbox (Version 7.3, Eigenvector Research, Inc.) e Matlab® (Version 7.11.1 The Mathworks, Inc.). I primi risultati relativi ai sei pigmenti in esame, soprattutto nel range dello SWIR, hanno dimostrato che esiste una correlazione tra le firme spettrali dei pigmenti in polvere analizzati e quelle dei campioni realizzati mescolando i sei pigmenti con i quattro leganti applicati sui due supporti, prospettando, dunque, nuovi scenari analitici per la caratterizzazione degli strati pittorici. L'approccio analitico sviluppato permette di ottenere in maniera rapida e non distruttiva informazioni non solo sul tipo di pigmento, ma anche sul legante e sul supporto. Scopo ultimo è quello di aumentare i casi di studio su cui applicare la metodica: si stanno attualmente preparando e analizzando nuovi provini di pigmenti con diverse combinazioni di strati pittorici, al fine di condurre nuovi test non solo su campioni tal quali ma anche invecchiati in solar box con differenti tempi di esposizione. Un tale approccio analitico potrebbe consentire di eseguire un monitoraggio completo dello stato di conservazione di una superficie dipinta così come la caratterizzazione dei suoi materiali costitutivi, in confronto con altre tecniche analitiche convenzionali

Preface - YOCOCU 2012, an efficient collision!

In chemistry for a collision to be efficient, i.e. breaking atomic bonds allowing the formation of new molecules and compounds, the reagents have to collide with an energy that is proportional to the bond strength and a direction that depends on the molecular geometry. This is what happened during YOCOCU 2012 (YOuth in COnservation of CUltural heritage), that took place at the Hof van Liere in Antwerp, Belgium on 18-20 June 2012

A scientific approach in the recovery of the historic center of Rome: limits and potentialities of the “color plan”

The development of studies about conservation of historic centers has highlighted the importance of interventions on the color of the plastered facades. The study of a color plan in city centers has been the subject of numerous debates in Italy, particularly in complex cases such as the historic center of Rome. Over the past thirty years also the development of new products for the construction industry has introduced the problem of materials selection and evaluation of their compatibility in historic urban context. By a preliminary analysis of the current legislation it is clear only the definition of general precepts without giving clear rules for the restoration of plasters and colors. The aim of this study is to compare the results obtained from this survey with the current "Plan of protection of the urban image of Rome", to highlight the potentialities and limits of existing regulations and to better understand the tools to be used for the restoration of historic buildings

Microclimatic Monitoring for Archeological Shelters Across Indoor Comfort and Conservation: The Case Study of the Villa del Casale in Piazza Armerina (Sicily, Italy)

Conservation and use raise priority and complementary needs in the archeological built heritage and, within the contemporary paradigm, they are no longer conflictual activities. The minimum intervention principle and compatibility are key objectives to avoid altering the values of the heritage. However, the musealization process also requires a double focus: on the one hand, the conservation of the material asset; on the other, the well-being of the users. The influence of environmental parameters on material decay is a well-known item: this occurs through chemical, physical, and biological processes, which contribute to reducing the expected life of archeologi- cal finds. Furthermore, the conditions of thermo-hygrometric comfort are necessary to guarantee the correct use of the site. The paper focuses on the thermo-hygrometric well-being in archeological sites and, in particular, on the case of Villa Romana del Casale, in Piazza Armerina, Sicily, which is a UNESCO site. A complex restoration project was performed on this site a few decades ago, aimed at improving the conservation of the mosaic apparatuses and users’ well-being, through the redesign and consequent replacement of the shelter system. The microclimate monitoring, aimed to verify the environmental conditions created by the new covering system, has been focused on sample room, on which the new covering system has been completed, and rooms that still are covered by the methacrylate old system. The comparison between the environmental parameters related to the old covering system, which caused undesired effects both for use and conservation, and the data related to the new covering system, allowed verifying the improvement in microclimatic conditions after the intervention. Data have demonstrated that the new one has reduced temperature inside the rooms and has increased humidity values. These analytical data demonstrate that the conservative intervention provided a positive impact on microclimatic conditions. Indeed, the comparison also showed the absence of the dangerous greenhouse effect. The conclusion of the paper will propose a comparative analysis of these results and other general aspects of the quality of the intervention, which cannot be measured or can only be measured indirectly