Science for art: multi-years' evaluations of biocidal efficacy in support of artwork conservation

In recent decades, the relationship between Science and Art has been gradually strengthened through the use of diagnostic, conservation, and valorization technologies. New technologies can also be used to support the creation and durability of bio-artworks. Within such a context, starting from the Spring of 2014, we performed in situ experimentations to eventually increase the durability of the graphical artwork of William Kentridge on the Lungotevere embankments, whose creation was scheduled in the following years. We applied various combinations and concentrations of three different biocides (Algophase, Biotin R, and Preventol R80) and two water repellents (Hydrophase surfaces and Silo 111) on 34 test areas. However, the artist preferred to leave his artwork to a natural fading. Right before the realization of the graphical artwork "Triumph and Laments of Rome" in 2016, just the black biological colonizations mainly composed of cyanobacteria were removed through pressurized water. We monitored the artist's work through analyses of images and colorimetric variations and such drawings showed a duration of 4 years in the natural conditions of recolonization. Here we show how the recolonization of treated and control areas, analyzed with the same methods, showed an increased duration, 3 years longer than under natural conditions in the case of Preventol R80(& REG;) and Biotin R-& REG; plus Silo 111(& REG;). The tested solutions showed differential effectiveness and multiple possibilities of use to support the maintenance of the artwork if the artist wanted to preserve his artwork for a longer period

Iterference test of green biocides on mural painting from hypogean monument

Due to the specific microclimatic conditions, mural paintings placed in hypogean monuments occur to biological attack. The application of natural biocides, safe and eco-friendly, is the bet- ter solution to prevent biodeterioration phenomena in this context. Lately, many new green biocides have been developed but applied in the conservative intervention only to a minor ex- tent; because of the fewer data about the interaction of the new products with the substrate. This study aimed to investigate the interference test of four green biocides on mural painting in Etruscan tombs (Necropolis of Monterozzi, Tarquinia). Mock-ups of Etruscan mural painting were reproduced and tested in similar hypogean microclimatic conditions. Colorimeter, contact sponge method and portable optical microscope were applied

Detection of endolithic spatial distribution in marble stone

Summary: The penetration of endolithic microorganisms, which develop to depths of several millimetres or even centimetres into the stone, and the diffusion of their extracellular substances speeds up the stone deterioration process. The aim of this study was to investigate, using a confocal laser scanning microscopy with a double-staining, a marble rock sample by observing the endolithic spatial distribution and quantifying the volume they occupied within the stone, in order to understand the real impact of these microorganisms on the conservation of stone monuments. Often the only factors taken into account by biodeterioration studies regarding endolithic microorganisms, are spread and depth of penetration. Despite the knowledge of three-dimensional spatial distribution and quantification of volume, it is indispensable to understand the real damage caused by endolithic microorganisms to stone monuments. In this work, we analyze a marble rock sample using a confocal laser scanning microscopy stained with propidium iodide and Concavalin-A conjugate with the fluorophore Alexa Fluor 488, comparing these results with other techniques (SEM microscope, microphotographs of polished cross-sections and thin-section, PAS staining methods), An image analysis approach has also been applied. The use of confocal laser scanning microscopy with double staining shows clear evidence of the presence of endolithic microorganisms (cyanobacteria and fungi) as well as the extracellular polymeric substance matrix in a three-dimensional architecture as part of the rock sample, this technique, therefore, seems very useful when applied to restoration interventions on stone monuments when endolithic growth is suspected

Advances in testing the interference of biocides on stone materials: A comparative analysis and guidelines for a standardised approach

Many biocidal products are applied to stone monuments as a conservative treatment against biodeterioration. However, checking national and international committees for the Conservation of Cultural Heritage and scientific literature, it stands out that most standards define single tests, but in the case of biocides, a well-defined standard methodology to check their interactions with the substrate is not drawn up yet. The present work thus provides comparative evaluations and suggestions to monitor the potential interference of biocides on stone materials. For this purpose, we built a dataset based on fifty scientific papers dealing with interference tests on biocides, and then we compared several methods and the obtained results, considering different biocides, stones and modes of application. The comparative data point out that the most investigated features are: changes in the surface colour, using colourimetry methods; water absorption, using capillary rise; contact sponge; contact angle; and morphology, using Scanning Electron Microscope (SEM). Here, we also provide a guidance standard on these methodologies, considering both in situ and in-laboratory analysis.(c) 2023 The Author(s). Published by Elsevier Masson SAS on behalf of Consiglio Nazionale delle Ricerche ( http://creativecommons.org/licenses/by-nc-nd/4.0/

DIFFERENTIAL EFFECTS OF TREATMENTS ON THE DYNAMICS OF BIOLOGICAL RECOLONISATION OF TRAVERTINE: CASE STUDY OF THE TIBER’S EMBANKMENTS (ROME, ITALY)

Monuments exposed to the environment are subject to numerous causes of degradation, including the action of biological organisms forming patinas and crusts of various colour and different aggressiveness. However, these patinas can be used in contemporary art for the creation of drawings, as in William Kentridge’s project, along the embankment of the Tiber River, illustrating the “Triumphs and Laments” of Rome history. More than eighty figures will be created through selective cleaning of the black biological patina on travertine, which is much used in Rome but little studied in biocide tests. The aim of this study is to understand which chemical treatments could delay the biological growth in the cleaned area, extending the lifetime of the images. Three commercial biocides (Algophase®, Biotin R®, Preventol R80®) and two water-repellents (Hydrophase superfici®, Silo 111®) were chosen and tested in situ (30 tests areas, with three repletion) using different concentrations and mixtures, in accord with the safety of users and environment. In order to limit the re-colonization after treatments, colour measurements and portable optical microscope were conducted both on the bare surface of the stone (the control test) and on the stone after chemical treatments.The results show that each product has different biocidal efficacy and a different colorimetric response. The preventive treatment of Preventol R80® with subsequent application of biocides in mixture had the best results in preventing re-colonisation. The use of water repellents alone was revealed to be ineffective in preventing biological recolonization and also determined colorimetric alterations in terms of brightness.The experimental data has provided an improved understanding of the effects of chemical treatments on travertine and of the phenomena of biological recolonization dynamics

Assessing the Impact of Lichens on Saint Simeon Church, Paşabağ Valley (Cappadocia, Turkey): Potential Damaging Effects versus Protection from Rainfall and Winds

The impact of lichens on the conservation of monuments, such as the World Heritage Site (WHS) of Cappadocian churches, presents a multifaceted challenge for conservators. Previous studies have shown that lichens can both induce deterioration processes of stone through their penetration into the substrate and chemical interactions as well as provide bioprotection, forming encrustations including calcium oxalate layers, which help mitigating the effects of weathering, reducing water penetration and eolian erosion. Evaluating the impact of lichens requires a comprehensive understanding of various factors, which include the type of rock substrate, the colonizing lichen species, the monument architecture, and the prevailing physic-chemical weathering processes. This study aims to provide a comprehensive analysis of the impact of lichen colonization on Saint Simeon Church in the Pa & scedil;aba & gbreve;& imath; Valley (Turkey) with a multidisciplinary approach to investigate the interplay between lichens, microclimatic conditions, and the degradation of stone. Specifically, this study examines the influence of wind-driven rain (WDR) occurrences on lichen distribution and stone weathering to develop comprehensive conservation strategies. The results confirmed the previous observations and showed a prevalence of the protective role of lichens over their deterioration. The northwest side of the church, despite being heavily impacted by environmental factors such as WDR and freezing-thawing cycles, showed reduced deterioration due to extensive lichen coverage. In contrast, the northeast side, with lower lichen colonization, demonstrated more severe deterioration. These findings suggest that integrating the protective aspects of lichen colonization into conservation strategies can enhance their preservation

Comparative evaluation of antimicrobial activity of green biocides on infected substrata reproducing original materials of Italian tombs

The hypogeal cultural heritage due to their favourable environmental conditions can be subject to microbial attack usually controlled using biocides. Recently the number of products allowed in the restoration practice has been reduced because, in addition to their effectiveness, the biocidal product should not have effects on the treated surfaces, and it should be safe for the operator and environment. Following this field research, we propose a reconstruction experiment in which we tested 4 different natural products (Clove oil, Oregano Oil, Usnic Acid, IPA+ DMSO + Usnic Acid) on tiles, reproducing the substrate of Etruscan hypogeal tombs (Macco) of Monterozzi Necropolis, inoculated with a selection of fungal/bacterial strains. After one month from the biocide’s application, we evaluated their efficiency by image analysis and by culture analysis. The achieved results evidenced a clear gradient between the four tested biocides and gave suggestions for further improvements