Forced wetting of a reactive surface

► Complex interaction of water with gelatin-coated PET revealed by forced wetting. ► Hydrophobic to hydrophilic transition modelled by zeroth order kinetics. ► Superficially similar results with uncoated PET are due to surface heterogeneity. ► Molecular-kinetic theory of wetting can interpret the results for both surfaces. ► The work has general implications for studies of reactive wetting.