# Recent Advances in Bio-Based Wood Protective Systems: A Comprehensive Review
## 3 Bio-Based Preservatives and Impregnators
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Matrix/Additive** & **Properties** & **Results** & **Ref** \\ \hline Tung oil + hemp-derived & Improved protection against the & Evolution of L*, a*, and b* below 0.5 during & [50] \\ biocarbon & weathering effects & 180 days of natural weathering & \\ Linseed oil + nanofibrillated & Improved wear resistance & Water contact angle above 90\({}^{\circ}\) after & [51] \\ cellulose & & 20 Taber cycles & \\ Bio-based epoxide amine & Decreased water absorption & Water absorption reduced to 73.42\% after 168 h & [53] \\ Castor oil & Increased hydrophobicity & Water contact angle increased from 70\({}^{\circ}\) to 100\({}^{\circ}\) & [58] \\ Castor oil + SiO\({}_{2}\) nanoparticles & Increased hydrophobicity & Water contact angle increased from 80\({}^{\circ}\) to 160\({}^{\circ}\) & [60] \\ Epoxidized soybean oil & Increased hydrophobicity & Water absorption reduced to 40\% after 40 days & [62] \\ Acrylated epoxidized & Increased pencil hardness & of soaking & \\ soybean oil & and adhesion & Pencil hardness of 2–3B and adhesion of 4B & [65] \\ Vegetable resins + oil extracted & Improved tensile strength & Tensile strength between 10 and 30 mPa & [66] \\ from seeds of Jatropha curcas & Increased protection against termite & Mass loss reduced from \(\approx\)45\% to less than 2\% & [70] \\ Cellulose nanofibril + graphitic & Improved colour stability & Colour change reduced from 16 to 3 after & [75] \\ carbon nitride nanosheets & Improved colour stability & 15 days of UV-A exposure & [76] \\ Lignin-based polyurethane & Moderate hydrophobic & Water contact angle between 79\({}^{\circ}\) and 85\({}^{\circ}\) & [76] \\ Fish gelatine & Improved fire resistance & Peak heat release rate pHRR of 64 Wg\({}^{-1}\) and & [78] \\ Luteolin-derived epoxy resin & Improved fire resistance & Peak heat release rate pHRR of 373 kW/m\({}^{2}\) & [81] \\ Polyphenolic resins from & Improved anti-flammable & Reduced heat of combustion release of about & [83] \\ tannins and lignin & performance & 19.9 MJ/kg & [84] \\ Polyurethane + benzoxazine & Increased hydrophobicity & Water contact angle increased from & [84] \\ Bio-based diol synthesized & Improved mechanical & 115\({}^{\circ}\) to 150\({}^{\circ}\) & [86] \\ from vanillin & properties & High pencil hardness (2H) and scratch & [86] \\ Living fungus & Improved aesthetic durability & Colour change reduced from 14 to 1 after & [90] \\ _Aureobasidium pullulans_ & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._degradation, especially by _Rhodonia placenta_. Positive outcomes were obtained from pyrolysis distillates from the bark of spruce, which could inhibit fungal growth over 40% at a concentration of 0.1% [93]. [PERSON] et al. investigated the performance of lichen and leaves of mistletoe for wood preservation [94]. Even if the results of the fungal decay test were not satisfactory, according to the standard reference, some promising outcomes were highlighted, prompting efforts toward this trend of research flow. Tannins, of which many plants are a great source, are among the most explored and investigated natural extracts with potential as antifungal agents. Low concentrations of tannins extracted from cones of spruce and pine and from spruce barks could inhibit the growth of brown-rot fungi. However, they could not block the growth of white-rot and soft-rot fungi [95]. Therefore, although tannins might constitute promising agents for wood preservation, further deeper investigation is required. In a later study [96], tannins were reported as natural wood preservatives, where they could improve resistance toward the white-rot fungus _Pycaporus sanguineus_ at a comparable level to that of the chromate copper borate preservative. The potential inhibitory characteristics of valonia, chestnut, tara, and sulphited oak tannins were also tested. Similarly, these tannins displayed anti-fungal performance against brow-rot fungi, but not against white-rot fungi [97].