# Recent Advances in Bio-Based Wood Protective Systems: A Comprehensive Review
###### Abstract  
This review emphasizes the recent ongoing shift in the wood coating industry towards bio-based resources and circular economy principles, promoting eco-friendly alternatives. In addressing wood's vulnerabilities, this study investigates the use of natural compounds and biopolymers to enhance wood coatings. These materials contribute to protective matrices that safeguard wood surfaces against diverse challenges. Essential oils, vegetable oils, and bio-based polymers are explored for their potential in crafting eco-friendly and durable coating matrices. Furthermore, this review covers efforts to counter weathering and biological decay through the application of various natural compounds and extracts. It evaluates the effectiveness of different bio-based alternatives to traditional chemical preservatives and highlights promising candidates. This review also delves into the incorporation of sustainable pigments and dyes into wood coatings to enhance both protective and aesthetic qualities. Innovative pigments are able to provide visually appealing solutions in line with sustainability principles. As the wood coating industry embraces bio-based resources and the circular economy, researchers are actively developing protective solutions that encompass the coating matrix, preservatives, bio-based fillers, and natural-pigment dyes. This review showcases the continuous efforts of academia and industry to enhance wood coatings' effectiveness, durability, and sustainability, while maintaining their aesthetic appeal. wood coatings; bio-based additives; green solutions; wood protective systems; circular economy +
Footnote †: journal: _Sci._  
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Similarly, nanostructures with enhanced hardness, stiffness, and thermal stability, like nanosilica [20], nanoalumina [21], nanoclay [22], and nanocellulose [23], have been utilized to augment the mechanical properties and water resistance of wood coatings [24]. Additionally, the antibacterial and fungicidal properties of wood coatings have been fortified by the integration of nanomaterials, like copper nanopowders [25], nanotitanium [26], and silver [27]. Nonetheless, the emerging trend of using coloured paint to impart specific aesthetic effects to wooden products, employing novel pigments [28] and distinct gloss values [29], is gaining traction in the wood protective coatings sector [30]. The stability of these pigments in wood paints has recently garnered significant attention [31]. It is crucial to ensure that the incorporation of innovative pigments delivers unique aesthetic effects without compromising the protective barrier properties of the organic coating. The combination of wood paints with different types of pigments may lead to significant challenges, such as reduced protective efficacy due to matrix discontinuities or concerns regarding the pigments' limited durability [32]. At present, the wood coating industry is embracing two pivotal areas: bio-based resources and the circular economy. As the industry increasingly seeks ecologically friendly and multifunctional alternatives to conventional synthetic fillers [33], which often overlook environmental sustainability during production [34], scientific exploration is focusing on the integration of natural additives in coatings [35]. In this vein, researchers have recently examined the impact of incorporating various substances into wood coatings, including linseed oil [36], cellulose fibres [37], pigments derived from wood waste [38], microbial dyeing [39], and pigments extracted from fungi [40] and microalgae [41; 42]. Hence, this review reveals the latest methods employed to develop protective solutions for wooden elements considering the four aspects shown in Figure 1, namely the coating matrix, the materials for preservatives and impregnating agents, the bio-based fillers, and the natural-pigment dyes.