This study conducted a comparison between biocide treatments based on nanoparticles of silver, copper, ZnO, TiO₂ and silver/ TiO₂ nanocomposites to analyse their capability to inhibit microalgal fouling on stone buildings. Biofouling is one of the main alterations on stone façades, causes degradation of their constituent materials and interferes with their aesthetic values. The proposed treatments were tested on a limestone from the historic quarry of Estepa (Spain), widely used as construction material in the South of Spain. The applicability of the treatments was evaluated by colorimetry. The biocidal effectiveness of the nanoparticles was studied on stone surfaces by multispectral imaging, digital image analysis and optical coherence tomography. This is a low-cost and efficient protocol to validate biocidal treatments for limestone monuments, and our results demonstrate the potential of silver and ZnO nanoparticles as a protective treatment for stone façades. The results have implications for practitioners working on historic buildings.

This article discusses the usability of the Art-Risk 3.0 software for research on the conservation of heritage buildings. It is a new and free software based on fuzzy logic, which enables the assessment of preventive conservation and surveillance of the restoration of heritage buildings over a period of time. This artificial intelligence-based tool considers the vulnerability of buildings, their environments, and their management to evaluate the necessity of their restoration or preventive conservation. To validate the Art-Risk 3.0, 500 theoretical case studies were analyzed, and a 14^th-century Mudejar-Gothic-style Church in Seville, Spain was studied both before and after its restoration to identify post-restoration changes. This proof of concept demonstrates the capability of the Art-Risk 3.0 software to analyze environmental impacts on the vulnerability, risk, and functional service life of buildings, and assess the effectiveness of restoration activities. Additionally, this software identifies the most problematic factors and the necessity of restoration.

Stone has been widely used as a construction material since ancient times, and its preservation is crucial in historical and contemporary buildings. Biodeterioration and other alterations cause damage in stone monuments which leads to the need for repeated actions. Nanotechnology is increasing the development of new products for construction and restoration, and new treatments based on nanoparticles have been developed for stone conservation, such as biocides or consolidants. These treatments avoid the disadvantages of traditional products, such as limewater for consolidation or quaternary ammonium salts as biocides and fulfil some of the requirements demanded by cultural heritage, i.e., effectiveness, compatibility with the stone and its aesthetic values, and durability. This manuscript reviews some of the main advances in the development and application of nanoparticles as consolidants and biocides to treat stone cultural heritage.

Scanning microscopy techniques have emerged as powerful scientific tools for analysing materials of architectural or archaeological interest, since the commercialization of the first scanning electron microscopy instrumentation in the early 60s. This study is aimed at reviewing and highlighting the significance of several scanning microscopy techniques employed in the protection of built heritage. The diffusion of scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis (SEM-EDX) is proven to be the widest among the available scanning microscopy techniques, while transmission electron microscopy (TEM) applications are steadily present in the field of built heritage protection. The building material characterization, the weathering mechanism investigation, and the development of compatible and performing conservation materials are some major research areas where the application of the aforementioned techniques is discussed. The range of techniques, along with aspects of instrumentation and sample preparation are, also, considered.