After fermentation
Some wines are ready to drink immediately after fermentation, others are matured in oak barrels for anything up to three or four years before bottling.
Conventional wines will be heavily filtered and dosed with sulphur dioxide before being put in the bottle.
Maturation
The age of the wood in which a wine is matured affects its flavour dramatically.
Old oak will add subtly to a wine, new oak will give it a strongly woody, vanilla taste and smell.
Heavily oaked wines are currently very popular. Most expensive wines are matured in 'one hundred percent new oak barrels' and proud of it.
One reason for this is that it is a good way to disguise a bad wine. The oak overpowers the flavour of the grapes and their quality becomes less important.
An oak effect can be achieved without the need for maturation by adding chips of wood to the wine directly, during fermentation. This is not uncommon.
Fining
Fining is a way of clarifying wine by passing a foreign substance through it.
The fining agent sinks slowly down from the top of the vat, collecting any particles as it goes.
Most natural wines are not fined at all. Those that are will only be fined with organic egg-white.
Fining agents used in conventional winemaking include in conbentonite, silicon dioxide gel, potassium ferrocyanide, metatarcic acid, and issinglass.
Filtration
Conventional wines are filtered to remove all bacterial life before they are bottled. Not only is this unnecessary, it damages the flavour of the wine.
A natural wine will either have been subject to a very light filtration, or no filtration at all. Even a filtered natural wine may not be limpid.
Sterile wine tastes sterile. A natural wine is a living thing, containing living bacteria, and it tastes alive.