There's a deposit in this wine! Negative comments are often heard about the sediment which is sometimes found in a bottle of wine, but this does not necessarily mean that we are dealing with a bad wine. It is very important, as a measure of quality, to check that a wine is clear. A cloudy liquid, with particles permanently in suspension may be a sign of a 'casse' - a breakdown in the colour and clarity of the wine. If, however, an aged wine has a powdery sediment this is not a cause for concern; these are substances in the wine which have polymerised and become insoluble over time. This does not affect the quality of the bottle, but one must be careful decant the wine before drinking. In Italian these wines are said to have a 'shirt' because of the coloration of the side of the bottle when it has been lying in the cellar for some time.
Certain sparkling wines may also have a deposit; this is due to a second fermentation in the bottle.
Small crystals may sometimes deposit at the bottom of a bottle of white wine. These indicate that the wine has 'cought cold' but they are merely tartrate precipitates and do not affect the wine.