Rigorous mathematical analysis of viscous free surface flows and comprehensive experimental analysis have been used to develop coating technology in the last 30 years. Theoretical analysis usually require advanced numerical methods to solve the mass and momentum-conservation equations coupled with the appropriate boundary conditions for flows with liquid-gas interfaces. Experimental analysis usually requires pilot plant trials and bench-top flow visualization experiments to reveal details of the flow inside the coating bead. The first attempts to visualize a coating flow were limited to displaying the free-surface configuration as a function of the operating parameters. Later, careful experiments were used to visualize streamlines with vortices inside a coating bead for different coating processes. Streamline visualization were crucial on enhancing the fundamental understanding of different coating flows. However, the application of quantitative methods capable of providing instantaneous measurements of the velocity field inside a coating bead is still rare. Velocity measurements in coating flows are extremely challenging because of the small scale, and the presence of liquid-air interfaces. In this work, the particle-image velocimetry (PIV) technique was used to study the flow between a rotating roll and a stationary plate, a prototype forward roll coating flow. Theoretical predictions of the same flow were obtained by solving the Navier-Stokes equations with the appropriate boundary conditions for free-surface flows. The velocity and the rate of deformation at each point were measured at different operating parameters. Some of the results were compared with the theoretical predictions. (c) 2006 American Institute of Chemical Engineers.