A traditional vertical plug or rod used to control the drain valve at the bottom of a mash tun. By lifting or lowering the staff, the brewer regulates the flow of sweet liquid out of the vessel while keeping the grain bed intact. While older setups relied on this manual wooden or metal rod, automated butterfly valves have replaced it in newer commercial systems.
Give the penstaff a slight twist and lift to start the runoff, but keep the flow slow at first.
In historic breweries, the penstaff was often the only way to prevent a stuck mash from pulling a vacuum on the false bottom.
Related terms
Mash tun
An insulated or heated vessel where crushed grains and hot water are mixed to convert starches to sugars.
Underback
A collection vessel located below the mash tun that receives the sweet wort as it drains.
Lautering
The process of separating sweet liquid wort from the spent grain solids after mashing.