Search

Preserving artworks from the attacks of biodeteriogens is a primary duty of humanity. Nowadays, restorers use chemicals potentially dangerous for both artworks and human health. The purpose of this work was to find a green and safe formulation based on natural substances with fungicidal activity to restore ancient oil paintings, particularly “Il Silenzio” (by Jacopo Zucchi) preserved at the Uffizi Museum in Florence, Italy. The study was divided into two phases. First phase (in vitro study): three essential oils (EOs) and four hydrolates (Hys) were analysed by GC-mass spectrometry and in vitro tested against six ATCC strains of molds. An emulsion based on the more active natural compounds was tested on aged and unaged canvases samples to evaluate both their fungicidal activity and the impact on chemical-physical parameters. Finally, an in vivo toxicity test performed on the Galleria mellonella model assessed the safety for health. Second phase (in situ application): the emulsion was sprayed on the back of the painting and left to act for 24 h. Biodeteriogens present on the “Il Silenzio” painting were microbiologically identified before and after the treatment. The emulsion formulated with C. zeylanicum EO and C. aurantium var. amara Hy showed the best antifungal activity both in vitro and in situ without altering the chemical-physical characteristics of paintings. Furthermore, no in vivo toxicity was shown. For the first time, a green antimicrobial emulsion based on Hy and EO, safe for operators, was used to decontaminate an artwork colonised by fungi before the restoration practices.

Kinkarakawa-gami wallpapers are unique works of art produced in Japan between 1870 and 1905 and exported in European countries, although only few examples are nowadays present in Europe. So far, neither the wallpapers nor the composing materials have been characterised, limiting the effective conservation–restoration of these artefacts accounting also for the potential deteriogen effects of microorganisms populating them. In the present study, four Kinkarakawa-gami wallpapers were analysed combining physical–chemical and microbiological approaches to obtain information regarding the artefacts’ manufacture, composition, dating, and their microbial community. The validity of these methodologies was verified through a fine in blind statistical analysis, which allowed to identify trends and similarities within these important artefacts. The evidence gathered indicated that these wallpapers were generated between 1885 and 1889, during the so-called industrial production period. A wide range of organic (proteinaceous binders, natural waxes, pigments, and vegetable lacquers) and inorganic (tin foil and pigments) substances were used for the artefacts’ manufacture, contributing to their overall complexity, which also reflects on the identification of a heterogeneous microbiota, often found in Eastern environmental matrices. Nevertheless, whether microorganisms inhabiting these wallpapers determined a detrimental or protective effect is not fully elucidated yet, thus constituting an aspect worth to be explored to deepen the knowledge needed for the conservation of Kinkarakawa-gami over time.

Heat shock treatments are an innovative and eco-friendly method to devitalize biodeteriogens of outdoor stone monuments. They consist in short (up to 6 h), mild (40–60 °C) thermal treatments applied to artificially wet surfaces, and are effective against lichens and bryophytes. Epilithic green algae, a polyphyletic and diversified group of photoautotrophs, are among the most important colonizers of stone monuments, forming conspicuous biofilms which cause chemical, physical and aesthetical damage to the substratum. Like lichens and bryophytes, they are able to face the extreme conditions of a stone surface but their resistance mechanisms are only partially known. The present study aims to test the applicability of heat shock treatments to six morphologically and phylogenetically distant green microalgae. Their survival mechanisms have been investigated in relation to photosynthesis and content of selected polyols and non-reducing sugars. Chlorophyll a fluorescence measurements and observations at the epifluorescence microscope demonstrate that the thermal treatments cause negative effects on all the species, although they do not necessarily kill the whole populations, as observed in all the lichens and bryophytes tested so far. The survival capability is discussed in relation to the production of extracellular polymeric substances and non-reducing sugars.

Many chemicals used nowadays for the preservation of cultural heritage pose a risk to both human health and the environment. Thus, it is desirable to find new and eco-friendly biocides that can replace the synthetic ones. In this regard, plant essential oils represent effective alternatives to synthetic substances for the preservation of historical monuments. Thymbra capitata (syn. Thymus capitatus) is a medicinal and aromatic plant growing in the Mediterranean area and endowed with important pharmacological properties related to its essential oil. Among them, the antimicrobial ones make the T. capitata essential oil an ideal candidate for industrial applications, for instance, as biocide for the inhibition and elimination of biological patinas of cyanobacteria and green algae on historical monuments. In the present work, we studied the chemical composition of the essential oil from T. capitata growing in Malta by gas chromatography-mass spectrometry (GC/MS). The major volatile component is the phenolic monoterpene carvacrol (73.2%), which is capable of damaging the cytoplasmic membrane and to interfere both in the growth curve and in the invasive capacity, though the contribution of minor components &gamma, terpinene and p-cymene cannot be disregarded. For the oil application on the stone surface, Pickering emulsions systems were prepared with an essential oil/water 1:3 mass ratio stabilized with kaolinite at 4 mass% in the presence of Laponite&reg, this allowed to limit the fast volatility of the oil and guaranteed a better application and an easier removal from the artefacts attacked by biodeteriogens both indoor and outdoor. This formulation caused the elimination of biodeteriogens from treated surfaces without residuals or films on artworks surface, and the effect was retained up to four months.

The biodeterioration of historic-artistic manufacts is related to several biological systems, including fungi and bacteria, whose metabolic activities and vegetative development have a direct consequence on the conservation of cultural assets. Generally, different chemical compounds are utilized as biocides in order to control biodeteriogens growth, but recently the attention has been focused on potential risks of their use towards human health (operators, visitors) and the environment. In order to develop alternative methods, various natural products have been tested, particularly to control the colonization by fungi and bacteria. In this study, antimicrobial activity of three different plant products, Tea tree essential oil, Calamintha nepeta and Allium sativum L. extracts, has been evaluated against Bacillus subtilis, Micrococcus luteus, Penicillium chrysogenum and Aspergillus spp. (previously isolated from colonized artworks) through three different in vitro antimicrobial assays (micro-dilution in microtiter plates, well plates diffusion and agar disc diffusion method). The bioassays show a different microbial susceptibility to plant extracts, establishing for each bacteria and fungi the Minimum Inhibitory Concentration (MIC) and defining the diameter of the growth inhibition area. This result supports the data reported in literature and shows an important potential suggestion for the possible use in the control of biodeterioration of cultural heritage, safe both for human health and environment.

Early diagnostics and documentation fulfill an essential role for an effective planning of conservation and restoration of cultural heritage assets. In particular, remote sensing techniques that do not require the use of scaffolds or lifts, such as fluoresence lidar, can provide useful information to obtain an overall assessment of the status of the investigated surfaces and can be exploited to address analytical studies in selected areas. Here we present the results of a joint Italian-Swedish project focused on documenting and recording the status of some sections of the part closed to the public by using fluorescence hyperspectral imaging lidar. The lidar used a tripled-frequency Nd:YAG laser emitting at 355 nm as excitation source and an intensified, gated 512x512-pixel CCD as detector. The lidar had imaging capabilities thanks to a computer-controlled scanning mirror. The fluorescence characteristics of fresco wall paintings were compared to those of fresco fragments found at the same archaeological site and separately examined in the lab using FT-IR and Raman techniques for the identification of pigments. The fluorescence lidar was also used to remotely detect the growth of phototrophic biodeteriogens on the walls. The fluorescence lidar data were compared with results from biological sampling, cultivation and laboratory analysis by molecular techniques. © 2013 SPIE.

A study was carried out on the biodeteriogenic vascular flora at the Royal Palace of Portici in southern Italy. In all, 160 species were found on the building, which represents approximately 35.5% of the flora found in the whole grounds (450 taxa). Ecological analysis of the plant population highlighted the decisive role of xeric climatic conditions, the lack of substrate, use of the site, and ordinary and restorative maintenance work. Therophytes (48.8%) broadly prevail over other biological forms. Most of the taxa censused (38.2%) may be considered ubiquitous and hence found at the same time on different types of substrate. Measured against the Hazard Index (HI), 62.5% of the species detected may be considered low-hazard (HI 0-3), 31.9% medium-hazard (HI 4-6) and 5.6% very hazardous (I.P. 7-10). Ailanthus altissima (Mill.) Swingle (HI 10), Ficus carica L. (HI 10) and Quercus ilex L. subsp. ilex (HI 9) were the species which had the most impact of the architectural structures in question A study was carried out on the biodeteriogenic vascular flora at the Royal Palace of Portici in southern Italy. In all, 160 species were found on the building, which represents approximately 35.5% of the flora found in the whole grounds (449 taxa). Ecological analysis of the plant population highlighted the decisive role of xeric climatic conditions, the lack of substrate, use of the site, and ordinary and restor- ative maintenance work. Therophytes (48.8%) broadly prevail over other biological forms. Most of the taxa censused (38.8%) may be considered ubiquitous and hence found at the same time on different types of substrate. Measured against the Hazard Index (HI), 62.5% of the species detected may be considered low-hazard (HI 0e3), 31.9% medium-hazard (HI 4e6), and 5.6% very hazardous (HI 7e10). Ailanthus altissima (Mill.) Swingle (HI 10), Ficus carica L. (HI 10), and Quercus ilex L. subsp. ilex (HI 9) were the species that had the most impact of the architectural structures in question.