In nature, some organisms can form hard tissues composed of mostly organic materials; for example, the jaw of the marine worm Nereis consists of mostly protein with a small amount of coordinated metal ions. The material processing from an initially soft/compliant hydrated state towards a hard/stiff dehydrated functional material follows pathways that are different from biomineralization. Studying the change in properties during such biological material transitions may unveil the underlying biological processing mechanisms. Herein, we focus on characterizing the dehydration dynamics of a simple bio-inspired synthetic model material system. In particular, we studied the changes in mechanical properties between the soft (hydrated) state and hard (dehydrated) state of mussel-inspired catechol-PEG gels via coordination bonds. By adapting the rubber-elasticity model, we quantified the crosslink density during dehydration to examine the underlying relation between temporal evolutions of mechanical stiffness and crosslinking behavior. This study will provide additional insights on the biological processing from soft to hard materials as well as inspire new ideas on sustainable material processing.