Citation: Sala-Luis, A.; Oliveira- Urquiri, H.; Bosch-Roig, P.; Martín-Rey, S. Eco-Sustainable Approaches to Prevent and/or Eradicate Fungal Biodeterioration on Easel Painting. Coatings 2024, 14, 124. https://doi.org/10.3390/ coatings14010124 Academic Editor: Mariaenrica Frigione Received: 22 December 2023 Revised: 11 January 2024 Accepted: 13 January 2024 Published: 17 January 2024 Copyright: © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). coatings Review Eco-Sustainable Approaches to Prevent and/or Eradicate Fungal Biodeterioration on Easel Painting Agustí Sala-Luis , Haizea Oliveira-Urquiri , Pilar Bosch-Roig * and Susana Martín-Rey Instituto Universitario de Restauración del Patrimonio, Universitat Politècnica de València, 46022 Valencia, Spain; agsalui@bbaa.upv.es (A.S.-L.); haiolur@bbaa.upv.es (H.O.-U.); smartin1@crbc.upv.es (S.M.-R.) * Correspondence: mabosroi@upvnet.upv.es Abstract: Eliminating and controlling fungal biodeterioration is one of the most important challenges of easel painting conservation. Historically, the pathologies produced by biodeterioration agents had been treated with non-specific products or with biocides specially designed for conservation but risky for human health or the environment due to their toxicity. In recent years, the number of research that studied more respectful solutions for the disinfection of paintings has increased, contributing to society’s efforts to achieve the Sustainable Development Goals (SDGs). Here, an overview of the biodeterioration issues of the easel paintings is presented, critically analyzing chemical and eco-sustainable approaches to prevent or eradicate biodeterioration. Concretely, Essential Oils and light radiations are studied in comparison with the most used chemical biocides in the field, including acids, alcohols, and quaternary ammonium salts. This review describes those strategies’ biocidal mechanisms, efficiency, and reported applications in vitro assays on plates, mockups, and real scale. Benefits and drawbacks are evaluated, including workability, easel painting material alterations, health risks, and environmental sustainability. This review shows innovative and eco-friendly methods from an easel painting conservation perspective, detecting its challenges and opportunities to develop biocontrol strategies to substitute traditional chemical products. Keywords: biodeterioration; fungi; prevention; biocidal methods; easel paintings; essential oils; light radiations 1. Introduction Cultural Heritage (CH) materials are susceptible to being complexly damaged physi- cally, chemically, and aesthetically by the growing and metabolic activities of living beings, as investigators know as biodeterioration [1]. Many studies have been performed con- cerning vegetal or microbiological biodeterioration on inorganic materials, such as mural paintings [2–5], stone buildings [6–9], or stone sculptures [10–14]. Easel painting biodeteri- oration is a less-studied topic, although, in the last ten years, there has been more interest in their biological control and prevention [15–20]. Different investigations worldwide conclude that issues such as climate change and global warming contribute to damaging historical buildings, archaeological sites, museums, and collections physically, chemically, or biologically [21–23]. In this way, new analysis and control methodologies are recently being discussed and developed [24,25]. Concerning biodeterioration, climate change phenomena such as seasonal variations, heavy rain, and global warming raise the risk of microbiological growth in tangible CH due to increased moisture and temperature (Figure 1)[22,26,27]. Due to this biodeterioration damage, bio- cides, which are generally toxic for humans and the environment, are frequently required. Coatings 2024, 14, 124. https://doi.org/10.3390/coatings14010124 https://www.mdpi.com/journal/coatings