Self-centering of small droplets on smooth surfaces. A tiny BADGE/JeffAmine droplet (< 0.01 µL) was deposited on alumina to overcome the de-wetting difficulties encountered during spin coating. The droplet was deposited by gently touching the alumina surfaces with a dispensing pipette. The resulting droplets are smaller in diameter than the maximum lateral field of view (≈ 550 µm) that the used SFA setup could capture without lateral scanning. This dimension allows for simultaneous FECO visualization of the BADGE/JeffAmine contact (see Monitoring alumina-BADGE/JeffAmine interface during cure) and a region just outside the BADGE/Jeffamine region (i.e., air or water). When the droplet was deposited on the upper surfaces and then slowly brought into proximity to the second (lower) surfaces, the droplet self-centered (i.e., slid) to the point of closes approach (PCA) of the crossed-cylinder configuration, driven by capillary forces. A shows a 250 µm diameter droplet of BADGE/JeffAmine at the moment of bridging the second surface (tsliding = 0 s). Velocity profiles at different locations across the droplet during the self-centering stage are shown in Figure . The velocity profile clearly shows the velocity gradient that the droplet experiences, driven by the front end of the droplet. Sometimes, the BADGE/JeffAmine droplet splits close to the rear end due to the significant velocity differences, reducing the volume that reaches the PCA.