Experimental study of dynamic wetting in reverse‐roll coating

The movement of the dynamic wetting line in reverse‐roll coating was followed in a series of experiments that gave position, XD, angle, θD and the critical metering roller speed, VM, cascade, for the onset of cascade. The data were correlated with operating conditions and compared with plunging‐tape air‐entrainment speeds, V*plunging. It was found that there was hydrodynamic assistance of wetting similar in form but smaller in magnitude to that reported in curtain coating. The correlated data for XD and θD also provide boundary conditions, which can replace the assumptions usually made in the simulations of reverse‐roll coating flows.