AbstractThe wet strength of handsheets subjected to dipping treatment by solutions such as glyoxal with Zn(NO3)2 as a catalyst, chitosan, and the crosslinking system of glyoxal and chitosan is studied in this paper. The crosslinking system achieved better wet strength performance than glyoxal or chitosan alone and slightly better than the sum of glyoxal and chitosan in the case of a curing temperature between 90 and 130 oC. However, handsheets treated by this crosslinking system became more brittle, which was shown by the reduction of folding endurance of the handsheets with increasing wet strength. The capillary rise and contact angle of the treated handsheets showed certain relations to their wet strength when the above solutions were used to improve the wet strength of the handsheets. The physical changes of the treated handsheets can provide evidence to explain the mechanism of wet strength development.