A laboratory scale continuous galvanizing simulator has been designed and used in order to study the effects of control parameters on interfacial Al take-up, with particular emphasis on hydrodynamic effects and very short immersion times, shorter than one second. Effects of Al concentration and process temperatures have also been studied. It was shown that Al take-up is extremely fast at the very early stages of the reaction, leading to the complete coverage of the steel within a tenth of a second, and that the reaction subsequently proceeded at a rate compatible with solid state diffusion through the inhibiting layer. A mathematical model is proposed to describe the take-up curves. Atomic force microscopy was used to analyze the morphology of the inhibition layer and energy dispersive X-ray spectroscopy for thickness measurements.