Vorlaufs

Vorlaufs is a German-derived term that denotes a pre-run or preflow—the portion of liquid or process that precedes the main operation. In brewing, Vorlauf refers to the initial runnings of wort from the mash tun during lautering. This early fraction is collected and often used to rinse and clear the mash bed, removing fine particles and reducing turbidity before the main lautering proceeds. Brewers may recirculate the Vorlauf to aid clarification, and then separate it from the main runnings or mix it back in depending on practice. The subsequent portions are known as Hauptlauf (main run) and Nachlauf (final runnings). The Vorlauf helps protect against undesirable tannins extraction and can influence the final beer’s clarity and flavor.

Outside brewing, Vorlauf is used in other processes to describe the warm-up or preflow phase preceding the primary operation. For example, in process engineering, a Vorlauf may be used to fill piping, purge air, or condition equipment to the correct temperature before the main production run. In film or media contexts, the term is less common in German; instead, “Vorlauf” may appear in technical descriptions to denote a lead-in or pre-roll stage.

Etymology: Vorlauf combines vor- (before) and lauf (run, flow). The term conveys the idea of a preliminary stage designed to prepare a system for the main action.

See also: Vorlauf (brewing), Nachlauf, Hauptlauf.