Decanting is a ritual which is very often misunderstood. It is not because a bottle is extremely expensive that it always needs to be decanted.
What are the reasons for decanting a bottle?
One of the main reasons is to remove sediments from the bottle. In this case you need to pour the wine slowly in a decanter to keep the maximum of deposits in the bottle. When working in a bar with deemed light, it is very useful to place a candle beneath the bottle to visualise the residues. It can be good to add a little filter for fine sediments.
The second main reason is to oxygenate the wine. It helps to soften the tannins and release desirable fruit aromas. It particularly works very well with young, tannic wines or natural wines which sometimes need some aeration to showcase their aromas.
It also helps to remove off-smell which can be trapped in the bottle. Some young wines, particularly made with low intervention still have some CO2 trapped in. Decanting the wine will allow to remove that unwanted fizziness.
When we should not decant or ,at least, be more careful
Some people like to feel the evolution of the wine through the bottle. It can be interesting, however it can require patience and often the last glass of wine is the best.
It i s not always recommended to decant a light pinot noir for instance. If the wine does not have enough body, the excess of oxygenation might damage it.
You also need to be extremely careful with very old wine, I would recommend to use a decanter with a narrow base to have less contact with oxygen or to decant a la Bordelaise (Double Decantation) . It means that you decant the wine as normal, to clear the wine from residue and allow some oxygene, but the wine is then poured back in the initial clean bottle to be served.
Double decantation is a technique which I particularly like, it is easier to serve the wine, we can still have the bottle on the table and it is a more gentle way to let the wine breath.
As all the service tips, the most important is how you feel about it as primarily the aim of wine is to provide pleasure.
Examples of Wine I would recommend to decant:
Rich natural wine from Valencia :
Powerful Corbieres :
Complex and intense St Joseph: