Most wine bottles have a deep, concave indentation on their bottom, especially more expensive ones like high-quality Bordeaux or Burgundy bottles.
This concavity is not just a bow to tradition, left over from when all bottles were made individually by hand. In other words, it is not just decoration, as some sources attest.
Why Do Wine Bottles Have a Concave Bottom?
The concave depression on the bottle of wine bottles does serve a purpose, although tradition certainly drives the making of such bottles.
The indentation on the bottom of wine bottles is called a punt. It is also sometimes called a kick-up, push-up, or dimple.
Purpose of Wine Bottle Dimple
The glass of the dimple or ‘punt’ part of the bottle is very thick and the shape helps provide structural strength to the bottom of the bottle.
Since wine bottles are stored on their sides, a regular thin-walled bottom could easily break should the bottle be tapped. Also, for Champagne or sparkling wines, the punt increases the strength of the bottle a great deal, providing more surface so that the bottle can withstand the pressure of the carbon dioxide gas, making it less likely to burst. The extra weight at the bottom of the bottle, as well, give the bottle more stability, so that it does not fall over as easily during use.
Some say that the punt serves to catch sediment from the wine, as it precipitates out of solution. The ring at the bottom collects the sediment which forms into a hard circle that does not as easily dislodge and enter back into the wine. However, since wine bottles are stored on their sides, and since there is a traditional process used to collect sediments near the cork, which can be more easily removed before decanting or pouring, and since high-sediment wines tend to be stored in sharply shouldered bottles that are better at catching sediments, the punt is not likely to serve much purpose for this function. Wine bottle manufacture is steeped in tradition, and any feature that seems to hold a certain advantage may well have appeared by accident, and then have been reasoned after the fact, including the punt. However, regardless of whether the features were specifically imagined and produced to serve a certain purpose, or they were already present due to the realities of the manufacturing process, or simply for esthetics, the advantages are still there.
The punt makes a good place for waiters, or anyone else, to place their thumbs while pouring wine but the punt was not originally place on the bottles for this purpose.
There are actually up to 9 different types of wine bottles, although tall slim types of bottles with differently sloped shoulders are the most common.