# Comparative Studies on Nanocellulose as a Bio-Based Consolidating Agent for Ancient Wood
## 3 Results and Discussion
### Characterization of Treated Degraded Wood Samples  
In Figure 3, the ten samples are shown: three for each consolidating agent and one untreated, before treatment (Figure 3(1)), immediately after (Figure 3(2)), after 19 h, (Figure 3(3)), and 50 days after application (Figure 3(4)). Immediately after application, some differences between the three consolidating treatments could already be observed: the CNC appeared to have a milky consistency and initially did not penetrate easily into the wood (Figure 4a); moreover, it was observed that this sample had a very high surface tension, which means that the drops, perfectly spherical, remained on the surface and slowly penetrated the wood. Nevertheless, the CNC did not create a film, and therefore did not block subsequent penetrations. On the contrary, the Paraloid B-72 penetrated well from the beginning (Figure 4b); for the Regalrez 1126, this was even possible to see in detail, as shown in Figure 4c. Some spots on the sheet were under the samples, demonstrating that the resin penetrated well into the wood and passed through the holes made by the woodworms. Figure 3: Wood samples treated with CNC (A), Paraloid B-72 (B), and Regalrez 1126 (C), and samples untreated (NT) during the processes of impregnation: (**1**) before treatment; (**2**) immediately after; (**3**) after 19 h; and (**4**) after 50 days. Table 1 shows the weights of the various samples before the application of consolidants, after 19 h, and one month after the treatment. As can be seen from the data shown in the table, immediately after the consolidating treatment, the samples' weight increased, and then decreased a little bit due to the drying and evaporation of the solvents in which the consolidants were dissolved. In addition, from this table, it is possible to see that the  
Figure 4: Detailed images of samples treated with (**a**) CNC, (**b**) Paraloid B-72, and (**c**) Regalrez 1126, immediately after application. samples treated with nanocellulose (samples A), one month after treatment, exhibited a slight weight loss compared to their pre-treatment weight, and that this was due to the margin of measurement error. On the contrary, the samples treated with Paraloid B-72 and Regalrez 1126 (samples B and C) increased their weights after one month. Sample images were obtained in reflected light and were collected with both visible and inducted ultraviolet light at two different magnifications (5\(\times\) with UV light, Figure 5a,c,e,g; 2.5\(\times\) with visible light, Figure 5b,d,f,h). From these images, it is possible to observe the deterioration of the wood. All samples showed signs of biodegradation caused by woodworms throughout the observed area; their presence is demonstrated by the clearly visible spheroidal excrements--for example, in Figure 5a, as indicated by white arrows [34; 35]. Moreover, another sign of degradation due to these xylophagous insects is the presence of numerous holes in all the samples, observable in almost all the images in Figure 5--also in this case highlighted with white arrows. As these holes have a very large size, and as the thickness of the samples is very thin, even after the consolidating treatment and regardless of the consolidating solution used they remained empty, as can be seen in the images shown below. Therefore, from this optical microscopy analysis--and in particular from the UV light images (Figure 5a,c,e,g)--in addition to highlighting the signs of wood degradation, it was also possible to assess the presence of the consolidants applied by the fluorescence, producing an image that was slightly light blue/grey. At the same time, the most important result obtained by the visible light images (Figure 5b,d,f,h) concerns the variation in the visual appearance of the treated samples.