Have you ever sipped a soft drink, beer, or bottled water and wondered, “Why don’t they fill the bottle to the brim?”
Soft drinks are a popular beverage choice for many, especially among the youth. However, have you ever noticed and questioned why these drinks aren’t bottled all the way to the top? Is it possible that manufacturers reduce the amount of liquid slightly to cut costs and increase profits?
According to manufacturers, the reason they don’t fill soft drink bottles to the brim is due to issues related to the pressure of gas inside the bottle.
The expansion of liquid when it meets the obstruction of the bottle cap causes great pressure that can push the cap off. (Illustrative image).
When producing bottles, manufacturers typically make the internal volume larger than necessary to ensure that the correct amount of liquid can be stored according to their standards while still leaving some space for air expansion.
This calculation is done to prevent situations where the storage temperature of the soft drink is higher than the temperature at which it was produced. This is to avoid the cap popping off when the liquid inside the bottle expands due to heat. If the liquid expands and meets the obstruction of the bottle cap, it can create significant pressure that forces the cap off.
If there is an air gap in the bottle, the expanding air will have enough space to compress, keeping the bottle safe; because liquids cannot be compressed, while gases can.
Additionally, when the liquid expands but is obstructed by the cap, high pressure can build up. Therefore, if the bottle were filled completely, the cap would pop off, affecting transportation and storage. In some cases, this situation can pose a danger to users.
Moreover, during the production line process, if the bottle is filled to the brim, the liquid could slosh over, damaging the machinery. When consumers open the bottle to drink, the full amount of liquid can easily spill onto their hands, clothes, or belongings.
Thus, the unique properties of liquids have led to changes in the production, transportation, and storage processes. That is why soft drinks are not filled to the top. This bottling method ensures the quality of beverage products and safety.
Another interesting point in the bottling of soft drinks is that manufacturers use screw caps for plastic bottles and metal caps for glass bottles. These techniques are designed to ensure safety and reduce breakage during the transport of bottled drinks.
