The use of traditional biocidal products in cultural heritage has suffered a slowdown due to the risks related to human health and the environment. Thus, many studies have been carried out with the aim of testing innovative and environmentally friendly alternatives. In this framework, this review attempts to provide an overview of some novel potential products with biocidal action, tested to counteract the process of degradation of paper and stone materials due to microbial activity, keeping in mind the sustainability criteria. In particular, we have focused our attention on the testing of nanotechnologies, essential oils, DES (deep eutectic solvents) with low toxicity, and colloidal substances for conservation purposes.

Air pollution can have a significant impact on stone materials used in monuments, buildings, and sculptures. Sulfur and nitrogen oxides are particularly harmful pollutants, especially in carbonate stones. These oxides, reacting with moisture in the air, result in the formation of acids able to erode the stone surface and gradually compromise its structural integrity. The acids can also combine with airborne particulate matter, heavy metals, and salts, leading to the development of black crusts. These not only have detrimental effects on the stone’s integrity but also affect the original appearance of the surfaces, threatening the conservation of important monuments and buildings. This review discusses the characteristics of black crusts and their relation to the environment and stone materials.

This paper presents the results of a laboratory experimentation carried out on stone materials in the framework of the CRATI project (Knowledge and Restoration through Advanced Integrated Technologies) aimed at testing new products with consolidating properties by means of an integrated methodological approach. After the preliminary characterization of stone materials collected in the pilot site, the second stage of the activities within the project were focused on the formulation and testing of products for the conservation of the same materials against decay, especially salt crystallization, one of the most aggressive and common degrading processes. The San Domenico Church, located in the old town of Cosenza (Calabria, Southern Italy) has been chosen as the pilot site and for the in situ tests. Several specimens with the same features of the stone materials used in San Domenico church were collected from a historical quarry near the city of Cosenza. These specimens were treated and then artificially degraded by salt crystallization tests in order to evaluate their susceptibility to weathering intensity. Three different consolidating products were used; respectively, two commercial and another one formulated in laboratory: (a) a suspension of nanosilica (Nano Estel^®); (b) a suspension of nanolime (CaLoSiL^®), and (c) a suspension of nano calcium-hydroxide dispersed in isopropyl alcohol and then mixed with diammonium hydrogen phosphate. A systematic approach, including minero-petrographic, geochemical and physico-mechanical techniques, was applied to evaluate (a) the nature and main features of materials; (b) the efficacy of consolidating treatments, and (c) the resistance of treated stone to the salt crystallization processes. The tested products demonstrated a significant efficiency to consolidate and protect stone material samples, enhancing their resistance to salt crystallization. Thus, such a case history may be useful in order to plan appropriate restoration interventions that consider the interactions between the building stone and the protective/consolidating product.

Natural stones have represented one of the main building materials since ancient times. In recent decades, a worsening in degradation phenomena related mostly to environmental pollution was observed, threatening their conservation. The present work is focused on the minero-petrographic and geochemical characterization of black crust (BC) samples taken from the historical center of Naples, after selecting two pilot monumental areas. The latter were chosen based on their historical importance, type of material, state of preservation and position in the urban context (i.e., high vehicular traffic area, limited traffic area, industrial area, etc.). The building materials used and their interaction with environmental pollutions were studied comparing the results obtained by means of different analytical techniques such as polarized light Optical Microscopy (OM), scanning electron microscopy with energy dispersion system (SEM-EDS), X-ray powder diffraction (XRPD) and laser ablation coupled with inductive plasma mass spectrometry (LA-ICP-MS).

This work focused on the study of decorated pottery dated back to the 16th century from the Roman archaeological site of Villa dei Quintili, a monumental complex located in the south-eastern part of Rome (Italy). A minero-petrographic and geochemical study was undertaken to analyse five archaeological samples in order to define textural features and raw materials used for their production, along with the chemical and physical composition of the superficial decorative glazed coatings. For this purpose, different analytical methods were used, such as polarising optical microscope (POM), X-ray diffraction (XRD), micro-Raman spectroscopy, X-Ray fluorescence (XRF), and electron microprobe analysis coupled with energy dispersive spectrometry (EMPA-EDS). The results of such a multidisciplinary approach allowed us to achieve important results crucial to recognise the shards as majolica of the Renaissance period, improving knowledge about manufacturing processes of these renowned painted ceramic artefacts.