Being fussy here, the term is technically incorrect. Canned tennis balls are sealed but not “vacuum sealed”. The balls are sealed with a certain amount of pressure inside to ensure decent performance. The same thing goes for tennis ball cans.
Tennis balls need to be bouncy – and the specific pressure inside the ball ensures the bounciness of the ball. In general, the balls include 15 PSI inside pressure. The can is also sealed at the same pressure to keep the pressure of the ball intact.
The Science Behind the Sealing of The Tennis Balls
A variety of sports, including football and volleyball, use pressurized balls. However, tennis balls are different as there are no ways to pump them. Tennis balls are packaged in an airtight can to keep the inside pressure of the ball undamaged. The cans are also sealed in the same inside pressure as the ball.
As a result, when you remove the balls from the can, their lifespan becomes limited. Even if you don’t play with the ball, it will feel ‘dead’ after a few weeks due to the outside and inside pressure inconsistency. Besides, playing with the balls will deflate them quickly.
Because of these properties, it’s not advisable to open the tennis balls unless you are playing.
Why Are Tennis Balls Sealed?
Tennis balls usually come in a sealed canister, which is identical to the drink cans. But why do they seal tennis balls? As we mentioned earlier, the tennis ball cans are not vacuum sealed. Instead, they are sealed under the same pressure as the balls. The pressurized air keeps the inside pressure of the balls intact.
How long does an unopened can of tennis balls last? Just because the balls are stored in a sealed can, they will not last forever. The can’s air pressure will leak over time, and that’s why they arrive with an expiry date. Typically, an intact tennis ball can last around two years.
Pressureless Tennis Balls vs Pressurized Tennis Balls
The standard tennis balls are pressurized, as we discussed above. However, while shopping for tennis balls, you may come to see pressureless tennis balls. As the name suggests, the balls are pressureless and feel dead right out of the package. The balls are typically made of rubber materials.
The surface of these balls becomes softer after using them for a while. As a result, they become bouncy like the pressured balls. They arrive with a long-term lifespan. While the properties of the ball sound appealing, they are actually not. The balls are pretty heavy and require more effort to play. Although they are good for beginners and practise.
These balls can also increase the chance of injuries. They also don’t spin well, like the pressurized balls. Compared with the pressurized balls, the other variation may be affordable but not a suitable choice for ultimate performance. That’s why professional players do not prefer to use pressureless tennis balls.