Why Is The Bottom of Wine Bottles Concave or Indented?

why is bottom of wine bottle concave or indented

Most wine bottles in production have a concave bottom. This concave portion of the wine bottle is known as a punt.  Although nobody is completely sure why bottle makers first started creating wine bottles with punts, there are several advantages to concave wine bottle bottoms.  Punts make bottles easier to hold while pouring, catch sediment at the bottom of a bottle, enable wine to chill more quickly, make wine bottles easier to store, help the bottles withstand internal pressure, and make it easier to stand bottles upright.  Despite the lack of documentation regarding the exact origins of punts, most people agree one or more of the benefits provided by concave bottoms has allowed this feature to exist on wine bottles throughout the ages.

Origins of the Punt

Experts do not completely agree on the exact origins behind why bottle makers began creating concave bottoms.  Many people believe it may have been an artifact of the glass blowing process, which has been carried over into modern factory-made bottles due to tradition.  Others believe creating concave bottoms was the only way to ensure wine bottles could consistently be stable when placed vertically.  Regardless of the exact origin of this practice, its continued existence is proof that there are several benefits to creating wine bottles with punts.  It is worthy to note that in the modern era, many bottles and cans made for a variety of purposes have concave bottoms of varying degrees.  Even aluminum soda cans and liquor bottles contain slightly concave bottoms, suggesting there is a near universal practicality to this type of design.

Ease of holding

Punts make it much easier to grasp a bottle of wine from the bottom.  Servers can grasp the punt with the thumb and place the rest of the fingers around the lower portion of the bottle.  This allows servers to elegantly pour wine while securely grasping the bottle from the bottom.

Ease of storing

Punts make it easier to compactly store wine bottles.  The top of a wine bottle tapers, meaning the top part is narrower than the bottom part.  The punt allows the top of a wine bottle to overlap with the bottom part, which makes it much easier to compactly store wine bottles.  This allows winemakers and bottle makers to transport more bottles at a time.  It also allows wine collectors and restaurants to store a greater number of wine bottles within their premises.

Standing Upright

As mentioned previously, a possible benefit in older days was that punts helped keep wine bottles upright.  Before the development of factories, bottles would typically be made one by one using glass blowing methods.  Using this method, a person would use a blowpipe to manually blow air into a molten bubble of glass, and then shape this bubble into a bottle.  Although glass blowing allowed for great creativity in making bottles, it is undoubtedly less precise than modern factory methods of production.  Some theorize that it was somewhat difficult to create a flat bottom using glass blowing techniques, meaning such a bottle could tip over relatively easily.  In comparison, with a concave bottom, the bottle would be resting on a ring-shaped base, which would be much more stable in comparison.

Chilling Faster

A concave bottom increases the surface area of the wine bottle.  Objects with greater surface areas for a given volume can transfer heat at a higher rate.  This is beneficial for those who want to chill wine before consumption, as the higher surface area cause the wine to cool at a faster rate when placed in a refrigerator.

Withstanding Pressure

Finally, many people believe that the concave shape makes the wine bottles stronger, as it allows the bottle to handle higher pressures.  This is important for sparkling wines, such as champagne.  Sparkling wines release CO2 while in the bottle, which increases the internal pressure.  Rounded shapes tend to have a higher structural strength (to include arches and domes in architecture), meaning a wine bottle with a rounded bottom is more able to handle higher pressures.

Sediment

Traditionally, wine would often contain sediment, which consists of various byproducts of the wine making process.  This includes leftover yeast, grape residue, and any other ingredients which fall out of solution.  A punt creates a very narrow and deep ring shape on the outer portion of the bottom of the wine bottle.  This allows sediment to safely settle at the bottom of the bottle.  In contrast, with a flat-bottomed bottle, it is much easier for sediment to mix with the wine while being poured.  Wine drinkers do not want to drink sediment filled wine for obvious reasons, making a punt a useful way to maintain the quality of poured wine.  Modern winemakers can make wine without any sediment, making this an obsolete issue.  However, some believe that this was a possible origin story for the punt.

Myth: Wine Quality

Many people believe that the depth, size, or shape of a punt is somehow an indicator of the quality of the wine in the bottle.  This is incorrect, as there is no standard which governs how to associate punt size and shape with wine quality.  This would be an incredibly ineffective method of signaling wine quality, as cheaper wine manufacturers could easily create an elaborate punt to create the illusion of a higher quality wine.  In fact, the size of a punt is simply a matter of aesthetics.

Conclusion

Most wine bottles have a concave bottom, known as a punt.  There is no clear consensus on why punts were first added onto wine bottles.  One theory is that punts were a natural artifact of the glass blowing process, while another theory is that punts were created for the practical purpose of keeping wine bottles stable when placed vertically.  Regardless of why they were first formed, many people have theorized various theories as to why punts are beneficial.  Punts make it much easier to hold and pour wine bottles from the bottom, as the concave shape makes it easy to grip the wine bottle using the thumb and forefingers.  Punts also make it easier to compactly store wine bottles, as the narrow tops of wine bottles can partially fit within the shape of the punt.  Punts also increase the surface areas of wines, enabling quicker chilling.  They also increase the structural integrity of the bottle against pressure caused by sparkling wines.  Finally, many believe that punts were an effective way to keep sediment separated from wine during the pouring process.  Regardless of the exact origin of this piece of wine bottle anatomy, tradition and the various benefits of punts have ensured that they continue to be added to wine bottle designs all the way to the modern day.