Vorlauf

What does the term Vorlauf mean?

Vorlauf is the process of pulling the initial runnings from the mash tun prior to the sparge.  Wort removed from the lauter tun is added back to the top of the mash.  This process of recirculation helps to set the grain bed around the lautering/seperation device (e.g. false bottom, pipe manifold or stainless braid.).

Vorlaufing the wort helps remove large grain particles that may have slipped through the lautering manifold.  The process also aids in wort clarity by trapping large coaggulated proteins that may have formed during heating in the grain bed.

Vorlaufing can be perfomed simply through using a pitcher to collect wort and pour it back on the surface of the mash.  It can also be as elegant as using a pump to pull wort out and return it to the top of the mash via a return hose and manifold.

The primary thing to keep in mind when performing a vorlauf is to not add the wort to quickly to the top of the grain bed.  As this may disrupt the settling of the bed that vorlauf is meant to create.

For a couple references check these links below:
Homebrewtalk Wiki
RealBeer.com Discussion

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