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

Raman spectroscopy characterization of 10-cash productions from the late Chinese emperors to the Republic

This is the peer reviewed version of the following article: Montoya, Noemí, Montagna, Elena, Lee, Yu, Domenech Carbo, Mª Teresa, Doménech Carbó, Antonio. (2017). Raman spectroscopy characterization of 10-cash productions from the late Chinese emperors to the Republic.Journal of Raman Spectroscopy, 48, 10, 1337-1345. DOI: 10.1002/jrs.5218 , which has been published in final form at http://doi.org/10.1002/jrs.5218. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] The use of Raman spectroscopy for discriminating monetary emissions, a recurrent problem in much archaeological studies, is described. The method involves the record of Raman signatures of tenorite and crystalline and defective cuprite in the patina based on the idea that subtle, mint-characteristic variations in the composition and metallography of the base metal during the manufacturing process are reflected in the variation in depth of the composition and crystallinity of the corrosion patina. The technique was applied to a series of 10-cash copper coins produced around the transition between the Kuang Hsu and Hsuan Tung last Chinese emperors and the first Republic whose averaged composition was 95 +/- 1% wt Cu plus 5 +/- 1% wt Zn often accompanied by traces of Sn and Pb. Raman data, corroborated by focusing ion beam-field emission scanning electron microscopy and voltammetry of immobilized particles measurements, suggested the possibility of discerning between different provincial and regular unified currency productions.MINECO, Grant/Award Number: CTQ2014-53736-C3-1-P and CTQ2014-53736-C3-2-PMontoya, N.; Montagna, E.; Lee, Y.; Domenech Carbo, MT.; Domenech Carbo, A. (2017). Raman spectroscopy characterization of 10-cash productions from the late Chinese emperors to the Republic. Journal of Raman Spectroscopy. 48(10):1337-1345. https://doi.org/10.1002/jrs.5218S13371345481

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

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

Identification of endolithic traces on stone monuments and natural outcrops: preliminary evidences

Four different lithotypes of rock gathered from stone monuments and natural outcrops in Temperate and Mediterranean bioclimates, with endolithic microorganism colonization (cyanobacteria, fungi, and lichens), have been analysed by Raman spectroscopy. Endolithic microorganisms can penetrate actively into the rocks giving rise to biodeterioration phenomena. Often the biological origin of these deterioration phenomena is not recognized and confused with abiotic damages. The aim of this work is to identify by Raman spectroscopy the endolithic traces on stones, due to current or past biological colonization. The Raman spectra show the presence of bio-markers characteristic of the strategy adopted by microorganisms against strong UV-radiation and dry conditions, such as scytonemin, anthraquinone compounds, and carotenoids. Moreover, we have identified different geo-markers such as goethite and lepidocrocite because of the mobilization of iron by lichen metabolic activity. Importantly, we have identified for the first time by Raman spectroscopy, traces of endolithic microorganisms on stone monuments located in Temperate and Mediterranean bioclimate, where extreme climate conditions are not foreseen

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