Why Does Wine Need To Be Aerated
The purpose of using an Aerator is similar to that of decanting; it enables oxygen to infuse with wine. For most wines this will allow them to "open up" evoking more complex aromas and flavors to emanate from the wine. A great feature inherent in all aerators is that it can achieve the same result as decanting in a fraction of the time. Aerators are created in order to allow a maximum amount of air to be exposed to the wine in an extremely small amount of time. So for certain wines that may take 20-30 minutes to decant and open up, with just a few seconds through an Aerator can lead to the same end result. Most of them will also contain a screen of some sort in order to catch any sediment or lees that may be in the bottle, which is very common especially in older red wines.
It is important to point out, however, that Aerators are not magical devices that will make inferior wine taste good. It does not change anything in the wine and it cannot improve the actual quality. However it will take a young and tannic wine, or an older wine that has been bottled up for some time, and expedite the aeration process in seconds allowing a wine's full potential to be recognized.