As a tennis player, you’re probably familiar with the oddly satisfying “POP!” sound that a new can of tennis balls makes when you open it. But, have you ever wonder the reason behind this?… why do they have to come in an airtight can? In this article, we’ll help you find out!
Why do tennis balls come in a can? Tennis balls, which are filled with gas, are packaged in airtight cans to maintain the proper pressure inside the balls that are needed for an adequate bounce.
Once you open the can, the balls start to diffuse air because of the mismatch in air pressure, which is higher inside the ball in comparison to the pressure outside. Therefore, tennis balls are sold in these airtight cans to stop gas from leaking, and they can have the proper bounce for when they’ll be used for the first time on the court.
Below, we’ll discuss in more detail the reasons behind storing tennis balls in airtight containers.
Why an Airtight Can?
Pressurized tennis balls are packaged in airtight sealed cans at high internal pressure and taken out of the cans by breaking its seal only when the match play is about to start. Fresh balls are lively and have the required bounce.
The purpose of keeping the tennis balls in an airtight container immediately after its production until the beginning of a game is to maintain the technical specifications for the needed air pressure, as well as, the appropriate bounce.
The inside pressure in tennis balls itself pushes some amounts of air out of the ball. When the balls are hit across the net, they release microscopic amounts of air because of the pounding.
Over time, the ball loses much of the air inside, and the pressure is no longer the same. As a result, It loses its bounce and speed. And it’s time for the ball to be discarded, and/or given another used.
Opened Just Before the Match.
Have you ever wondered why the can of balls always remains sealed even though you have taken out everything else for the match — sneakers, grips, dampeners, racquets…? And yet the tennis balls container remain sealed until just before the start of the match.
It is because you need to open the can of tennis balls just before the match for them to have the best bounce they can offer. With time and use, these tennis balls start to lose their bounce and become unsuitable for tournament/or competitive matches.
The popularity of tennis comes because of the powerful shots that come at high speed, plus the players’ agility and technical expertise. To achieve such speed and power in the game, professional players give their best. But that is not enough. Even the racquets and balls have to play their part. Having a minimum range of bounce is essential to maintain the competitiveness of the game.
And, it is because of this reason that tennis balls are taken out of their cans just before the beginning of the game.
Life Outside the Can.
When opening a can of tennis balls, you’ll hear that “Pop!” sound of escaping gases from a high-pressure environment to the normal air pressure ambient. This is because the air inside, which has been kept at high pressure, begins to escape through the first narrow opening in the can.
So, if storing tennis balls in airtight cans is a necessity to preserve its original bounce, and liveliness, what happens when they are out of the can? One of the first things that happen is that is GAME TIME!
Jokes apart, the ball starts to experience a lack of equilibrium between the pressure outside and inside of the ball. With every bounce and breezy shot, some amount of air gets released from the ball, which robs off its bounce in small and tiny measures each time.
According to Tennis Express, once a new can of tennis balls is opened, they can maintain a proper bounce for about two weeks for the average club players. However, on most professional tennis tournaments, balls are changed every nine games during matches to make sure that the bounce of the ball remains uniform throughout the game.
Additionally, a BBC report suggests that, on average, a tennis ball can maintain its optimum bounce for up to three hours of play.
The Importance of an Appropriate Bounce.
Maintaining a suitable ball bounce is akin to maintaining the high standards of professional tennis. Pressurized balls, such as tennis balls, are designed and engineered to enhance the quality of the game and its competitiveness, without that, tennis would not be the same. And much of the credit for this goes to the unique and innovative packaging in which they come.
In some ATP & WTA tournaments, new cans of balls are stored in refrigerated containers so that the pressure inside the balls is not affected by the outside pressure and heat. During extremely hot weather (like in the Australian Open), tennis balls are more likely to let the pressure escape. This is due to the high temperature which causes the rubber molecules of the tennis ball to separate.
Pressure Canning.
The container in which balls are stored is pressurized to match the pressure of the balls. The amount of air inside the container is higher than its normal capacity, as it’s put under high pressure.
Since the pressure in the container is matched with that of the balls, it is a homogenous environment in which the air inside the ball does not come out. This helps maintain the quality of the balls until the last moments when the tennis match is about to start.
Besides great athletes, high-quality tennis balls, impeccable courts surface, racquet technology, among others, tennis fans must appreciate the contribution that ball containers play in keeping and maintaining the high standards of professional tennis. Without the precise technology used in preserving the original character of the tennis balls by packaging them in sealed pressurized cans, the balls would not perform with so much precision.
Short Life Span.
The pressure inside the tennis balls is of 26.7 pounds per sq inch, while the outside regular air pressure is only of around 15 pounds per sq inch. As a result, this makes the balls to release air in small quantities.
However, the gas inside the balls starts to diffuse through the rubber skin of the balls because of the high pressure. With time and every hit, the balls rubber frame softens and loses its resilience and bounce.
According to the University of Sydney, for tennis balls to be used in professional matches, they must bounce 53 to 58 inches when released from a height of 100 inches. Most standard tennis balls fail to achieve this after one month of being in use.
In tennis language, they go “dead.” This can happen to the balls after every competitive and/or tournament match. Depending on the use and players tennis level, the standard tennis balls can go dead after two weeks to one month.
Pressureless Balls.
As same as regular pressurized balls, pressureless balls are made of rubber, but the rubber is thicker and harder. Pressureless balls are good for practice. Unlike standard balls, the bounce does not go away easily in these balls. One drawback of pressureless balls is that they are heavier and more likely to cause injury when used. This one of the reasons, they are not used in competitive matches.
Compared to pressureless balls, out of the can standard balls are more bouncy, produce more spin, and travel faster.
Related questions
Why regular tennis balls have better bounce than other types of similar balls?
The reason why tennis balls have better bounce is that the air in the ball pushes outwards more forcefully than the impact that it takes when it hits the ground. This is made possible by keeping air in the ball at high pressure. The inside pressure in the ball gives it the strength to bounce back more strongly than the pounding it has taken.
Tennis balls come in air-tight cans, which have the same degree of pressure as the inside of the balls. As a result, this helps retain the pressure of the balls and the wanted bounce that comes with them.
Can a tennis ball still be used after its bounce is lost?
Yes; they can be still be used in your training program. You can use it to warm up your strokes while playing mini-tennis. Also, to improve your grip and hand strength, you can squeeze a tennis ball as hard as possible and release it, and repeat. Moreover, you can put an old tennis ball under the arch of your foot and allow it to roll. This can give you a soothing massage to your tired post-match feet.
In addition, you can use an old tennis ball to play fetch with your fluffy friend when you take him or her out for a walk.
Can Tennis Balls lose their bounce in a closed Can?
It depends on the quality and brand. According to different sources, the shelf life of a tennis ball can is around six months. However, many people claim that they have opened the can years after purchasing it and the balls had not been dead.
In the ’70s, pressurized devices were popular in which you could put the balls and give it a couple of pumps so that the balls wouldn’t lose their bounce too soon.