By Surabhi Ashok
According to experts, the indents present on a milk container allow bottle producers to control the container’s volume and structure during manufacturing.
Milk jugs are made of high-density polyethylene plastic, which shrinks in hot temperatures. Manufacturers make these jugs larger than needed in order to offset anticipated shrinkage during transportation or warehousing.
However, during the colder months of the year or when containers are sent directly to be filled, skipping long-term storage, volume inserts are installed so that producers do not have to change the base jug molds during manufacturing. These interchangeable inserts are the circular indents seen on the milk jug and ensure that the containers do not look underfilled.
Aside from supporting customer satisfaction, these plastic molds also mitigate unnecessary production costs as it avoids spilled milk waste that would have otherwise occurred due to container shrinkage.
Source:
Fact check: Meme falsely claims jug indents pop out if milk is old
Why do plastic milk jugs have a circular indent on the side? It may not be what you think