## 4 Applications of Cellulose Nanomaterials in Cultural Heritage
This framework takes into account the current EU legislative context (i.e., CLP and REACH regulations) and the requests of the conservators and restorers, with the aim to promote the selection and use of more sustainable and ecological nanomaterials in different conservation fields [63,65]. In this context, nanocellulose, with its very attractive properties and advantages, is very important and useful for the conservation treatments of cellulose-based artworks for many reasons: thanks to the dense hydrogen bonding network provided by this nanomaterial, it is possible to obtain an improvement in the mechanical properties of the treated cellulose-based object with the simple addition of functional groups for a more specific conservation action; moreover, nanocellulose-based consolidants can create transparent films that produce barrier effects towards oxygen, water and water vapor, and oil, which could damage artistic substrates, without altering the visual appearance of works of art; and, finally, another great advantage is the reversibility of these restoration strategies, which is achievable with the simple application of hydrogels, without causing any damage to the works [15; 59]. For the sake of clarity, Table 4 summarizes some advantages and disadvantages of nanocellulose applications for wood, paintings, and paper conservation. Here, several examples of different applications of nanocellulose are reported, such as the consolidation and reinforcement of ancient degraded wood [21], the chemical modification of wood adhesive [66], the preparation of cellulose and lignin nano-scale consolidants for waterlogged archaeological wood [18], the consolidation of cotton painting canvases [24; 25; 67], the combined stabilization and deacidification of cellulosic materials [61], and the increase in watercolor painting efficiency on paper [68]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Artistic Application Field** & \multicolumn{2}{c}{**Advantages**} & \multicolumn{2}{c}{**Disadvantages**} \\ \hline \hline  & \(\bullet\) & Compatibility & & \\  & \(\bullet\) & Good penetration & & \\  & \(\bullet\) & Increase in compression & \(\bullet\) & Decrease in adhesiveness \\  & & strength & \(\bullet\) & Possible coating \\  & \(\bullet\) & Good adhesion & & deformations after \\ Wood & \(\bullet\) & Increase in stiffness & & drying \\  & \(\bullet\) & Eco-friendly & \(\bullet\) & Irreversibility \\  & \(\bullet\) & Transparency & \(\bullet\) & Brittleness \\  & \(\bullet\) & Flexibility & \(\bullet\) & Shine \\  & \(\bullet\) & Tensile strength & & \\  & \(\bullet\) & Stability & & \\  & \(\bullet\) & Easily cleanable & & \\ \hline \hline  & \(\bullet\) & Compatibility & & \\  & \(\bullet\) & Eco-friendly & & \\  & \(\bullet\) & Increase in interaction & & \\  & & with substrates & & \\ Painting Canvases & \(\bullet\) & Increase in Young’s & \(\bullet\) & Slight yellowing \\  & \(\bullet\) & Recursibility & & \\  & \(\bullet\) & Lower weight increase & & \\  & \(\bullet\) & Stability & & \\  & \(\bullet\) & Resistance to humidity & & \\ \hline \hline  & \(\bullet\) & Compatibility & & \\  & \(\bullet\) & Eco-friendly & & \\  & \(\bullet\) & Adhesion & & \\  & \(\bullet\) & No optical effect & & \\  & \(\bullet\) & Stability & & \\  & \(\bullet\) & Low coating thickness & \(\bullet\) & Not always mechanical \\  & & (compared to Japanese & & reinforcement \\  & & paper) & & (depending on the \\  & & Better legibility & & solvent used) \\  & & (compared to Japanese & \(\bullet\) & Slight yellowing \\  & & paper) & & \\  & \(\bullet\) & Decrease in wettability & & \\  & \(\bullet\) & Decrease in air & & \\  & & permeance & & \\  & \(\bullet\) & Reversibility & & \\  & \(\bullet\) & Coating uniformity & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Some advantages and disadvantages of nanocellulose applications for wood, paintings, and paper conservation.