That small indentation on the bottom of the wine bottle is called the punt. So why is it there? Prior to the Industrial Revolution, all wine bottles were handmade by glassblowers. It served two purposes, first being, it is believe the “extra weight” of the glass on the bottle, ensured that the bottle could stand upright. The second was that when the seam was pushed up, no sharp point of the glass remained on the bottom to keep it flat and not toppling.
Today, most bottles are made by machines and having a flat surface on the bottom is very simple to produce. Tradition is hard to change as the punt continues to be on many of the bottles.
Some other reasons the punt has been suggested are:
*People thought it added to the bottles structural function
*Some folks believe it collects the sediment as a wine ages
*For sparkling wines under pressure, it does allow for more equal distribution of pressure.
In this picture, the punts ranged in size from ¼ of an inch to almost 2 inches. The size of the punt doesn’t have any correspondence to the quality or the quantity of wine inside. In fact if you were comparing two 750ml wines bottles on the local shelf, one being flat and the other having a two inch punt, you might consider the larger bottle thinking you were getting more wine. The fact is 750ml is 750ml! That is just some slick marketing to entice you into picking that bottle! Typically with a deeper punt, wineries will use a heavier bottle. This again is just consumer marketing and actually has a couple of negative effects. One is in handling and shipping costs and the other from an environmental perspective.
One of the classical ways you might have seen the punt being used is by Sommeliers, using a one hand pour a place to hold the wine bottle. The staff can hold the wine bottle by securing the thumb in the punt and with strong fingers extended down the bottle, shows an “opulent style” when pouring Champagne or wine. When doing so be careful if the bottom of the punt is wet and does not possess etching or embossed marks it can surely slip from your grip.