The rinsing of mashed grains with hot water in order to extract sugars, proteins, etc. from the grain. This requires the use of a manifold or false bottom in the mash tun. The liquid is collected in the kettle so that it may be boiled. In the brewing of beer from barley, this process generally includes the addition of hot water in the top of the mash tun while simultaneously draining sweet liquor out the bottom.