However, the results of different studies cannot be compared because of substantial differences regarding the type of chitosan derivatives used, the type of cellulose substrate and the method of application. As an example, Vartiainen et al. reported a 15% improvement in TI for copy paper sheets coated with 4.7 g/m² chitosan films. Considering the high relative porosity characteristic of copy paper sorts, this substantial improvement of tensile properties could be due to the high migration of chitosan into the internal structure of the substrate. M. S. Jahan et al." observed a 40% increase in TI for laboratory sheets obtained from acacia and bamboo pulps, using chitosan as dry and wet strength additive, demonstrating that the presence