A method for extending the gelation time of an oxidized polysaccharide to react with a water-dispersible, multi-arm amine to form a hydrogel is disclosed. The extension of the gelation time is accomplished by using a chemical additive. The method also extends the time for the hydrogel to become tack-free, and may also be used to decrease the degradation time of the hydrogel. The chemical additive reacts with the functional groups of the oxidized polysaccharide or the water-dispersible, multi-arm amine, thereby reducing the number of groups available for crosslinking. The use of the resulting hydrogel for medical and veterinary applications is described.