However, although the surface of fibers was completely CH-coated when three or more layers were applied, the polymer didnot fill completely the paper pores on its 3D structure, even withthe five layers. The presence of chitosan on the back of the sheet,shown in Fig. 5B, confirms that this polymer did penetrate throughthe fiber network. As expected, this effect was strongly dependenton the number of deposited chitosan layers, particularly for thefirst three applications