Sparging
After the mashing process is complete, the grains, water and sugar are still in suspension in the mash tun. The sugars are separated from the grains in a process called sparging (which is a bit like rinsing). The mash tun has a false bottom that is a fine mesh. This allows our brewer to draw liquid from the bottom of the grain bed.
Hot water at 60-70c is sprayed over to the top of the grain bed, run through the bed, and drawn off the bottom through the false bottom and out the boiling vessel. This extracts sugars from the grains and produces sweet liquid called wort for boiling. The initial runnings (first few gallons) drawn during the sparge process are recirculated back through the grain bed, as the early runnings often contain grain husks, crushed material and other undesirable elements.
After the initial runnings, the grain bed will act as a filter and reduce the cloudiness of the runnings. Sparging is best done slowly so that a maximum amount of sugar can be extracted from the spent grains. This sparge wort is then sent to our copper for boiling.