<p>We investigate the coupled effects of evaporation and sedimentation on the microstructural evolution of bidisperse colloidal films using lattice Boltzmann simulations. The drying process is examined under both continuous drying and a two-step drying protocol, in which a temporary interruption period is introduced during the rapid drying stage. Under continuous drying, the competition between evaporative accumulation and gravitational settling leads to distinct outcomes: a pronounced small-on-top stratification when large particles undergo stronger sedimentation, and a much weaker degree of such stratification when the sedimentation rates of the two particle types are comparable. When drying is temporarily paused, the dense particle layer formed near the air–liquid interface becomes gravitationally unstable, and exhibits Rayleigh–Taylor instability. During this quiescent period, size-dependent vertical stratification relaxes, while new lateral patterns featuring finger-like structures emerge. These lateral patterns subsequently influence the final film configuration, ultimately producing alternating regions enriched in small and large particles. These findings demonstrate that drying-induced instability through a two-step drying protocol provides a promising route for designing unique microstructures in colloidal films.</p> Graphical Abstract <p></p>