Take a Minute: Racking from Parrish Family Vineyard on Vimeo.
There are 3 times lees racking is done in wine making...
1st racking - Grape solids that are in the tanks
2nd racking - Done 2 to 3 months later in the barrel, lees usually are dead yeast cells and some leftover grape sediment
3rd racking - Happens at the very end of barrel aging, tend to be long-chain tannins that fall out of solution