The preparation of coffee by a variety of percolation methods (moka pot, espresso etc.) has received significant scientific exploration recently. Modelling efforts have focused primarily on deriving and solving physicochemical models for liquid flow, coffee dissolution kinetics and solubles transport in a coffee bed represented by a fixed or evolving porous media [1,2]. While such models have proven capable of reproducing experimental observations and delivering practical insights, most models assume a liquid-saturated coffee bed throughout brewing. In espresso brewing, unsaturated flow during imbibition may constitute up to one third of the brewing time and so it is of interest to investigate In this talk, a study undertaken to address this limitation will be presented [3]. Experimental data is collected using X-ray tomography to track the initial infiltration of water into a dry coffee bed during espresso brewing. The infiltration front location is extracted via a density contrast between wet and dry coffee, detected through a change in the X-ray absorption in the bed. Absorption data is collected in three dimensions with snapshots extracted at one second intervals for two different coffee grounds. Interestingly, for the finer grind, a sharp transition between wet and dry regions appears to establish quickly at a uniform depth in the cylindrical portafilter cross-section and moves into bed as infiltration progresses. A one-dimensional unsaturated porous medium flow model, dividing the bed into wet and dry regions, is developed to describe the infiltration front movement. The model incorporates the espresso pump dynamics and achieves good agreement with the experimental data. The model is used to consider the dependence of infiltration dynamics and saturation time on parameters of interest. Model improvements and coupling to coffee dissolution and solubles transport models to analyse the importance of the imbibition stage on the coffee extraction dynamics will be discussed. [1] Moroney, K.M., et al. Modelling of coffee extraction during brewing using multiscale methods: An experimentally validated model. Chem. Eng. Sci. (2015). [2] Giacomini, J., et al. Water flow and transport in porous media for in-silico espresso coffee. Int. J. Multiph. Flow (2020). [3] Foster, J., et al. Dynamics of liquid infiltration into an espresso bed using time-resolved micro-computed tomography: Insights from experiment and modeling. Physics of Fluids (2025)