Sediment is the solid material that settles to the bottom of any wine container, such as a bottle, vat, tank, cask, or barrel. Sediment is a highly heterogeneous mixture which at the start of wine-making consists of primarily dead yeast cells (lees) the insoluble fragments of grape pulp and skin, and the seeds that settle out of new wine. At subsequent stages, it consists of Tartrates, and from red wines Phenolic polymers as well as any insoluble material added to assist clarification.