Lifestyle

The genius reason why soft drink bottles are not flat

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When you reach for your favorite fizzy drink, do you ever wonder why soda and soft drink bottles have that distinctive design and not a flat base?

It’s not just an aesthetic choice but there’s a fascinating science and history behind it!

Origin and history

The evolution of design in soda and soft drink bottles has been quite interesting. In the 19th century, glass bottles mainly contained sodas with flat bottoms.


The early designs posed some challenges, though. The bottles were prone to breakage due to carbonation pressure because they were made with glass. With increased demand for carbonated drinks, there was a need for more toughness and efficiency in design.

The “Codd-neck” bottle in the early 20th century was an interim solution that had a marble and rubber washer mechanism to seal the bottle and prevent the gas from escaping. Still, it was in glass and had flat bottoms, which did not solve the pressure issue completely.

The major innovation was the plastic bottle PET that came into use in the 1970s. It had the possibility of much greater versatility in design. Engineers and designers used the versatility of this new material to develop bottles that could safely contain carbonated beverages, giving birth to the spike-bottom design.

The science behind the design

When carbonated drinks are cooled, the dissolved gases within the liquid can contract with that temperature change. It makes the pressure in the bottle fluctuate. A flat-bottomed bottle would struggle to contain this pressure, leading to potential breakage. The corrugation design of a spike-bottom bottle lets it expand and contract safely with temperature changes. This design spreads the internal pressure across the bottle evenly, avoids weak points, and strengthens a bottle as a whole. As a result, it makes the bottom of a soda bottle more resistant to the internal pressure created by carbonation.

Adds to the aesthetic element

In addition to functionality, the spike bottom design lends a visual flair that makes the bottle look good overall. This corrugated and segmented pattern at the base of this kind of bottle is slender and looks pretty sleek and modern. Such a design also sets it apart from the other types of beverage bottles as well.