Tennis Balls Are Full of Hot Air!
Tennis balls are unique in the world of ball sports. No other balls lose air pressure and become unusable. All other balls are either hard like golf balls, baseballs, softballs, etc. OR they are inflatable like footballs, volleyballs, etc. This uniqueness creates challenges that plague all players and coaches daily around the world. We ask ourselves, “Are these balls still good enough for a practice set?” or for coaches, “Is it time again to retire these balls and open another case of balls?” or for the customer in large sporting goods stores or any package goods store that sells tennis balls. There are so many choices? Aren’t they all the same? The answer is a resounding no.
If you’ve ever wondered about tennis ball pressure, read on.
In this blog, we will discuss air pressure with regular yellow tennis balls and also transition balls that are most often used with beginning and advancing juniors. They are designated with the colors red (beginner), orange (intermediate), and green (most advanced stage using transition balls).
Yellow ball cans of all brands add air pressure inside each can on top of the normal sea level air pressure of 14.7 pounds per square inch (14 psa) that exists on planet Earth! For yellow balls, 12 psi is added.
From Google: “Tennis balls are usually pressurized to 12 psi more than normal air pressure. Normal air pressure around us is 14.7 psi, therefore the pressure inside tennis balls is 26.7 psi. Tennis balls are sold in pressurized cans, with the pressure identical to the pressure inside of a tennis ball.”
Here are the facts about ball pressure and the three types of transition balls:
- Red balls have no pressure at all and are therefore never sold in pressurized cans.
- Orange balls add about 6 psi as compared to the regular yellow tennis ball added pressure of 12 PSI.
- Green balls fall about halfway between orange and yellow with approximately 9 psi added.
The other thing to keep in mind is that air molecules do pass through plastic … slowly. Put an unopened yellow tennis ball can in a closet for 2 years and it will not have the same pressure as it did originally. In fact, the balls may be completely flat. And, once a pressurized can is opened, the air molecules escape quite rapidly, escaping through the rubber wall and the felt of the ball. This is the reason that once a pressurized can is open, it is only a matter of days before the balls noticeably lose pressure and gradually become unplayable.
It should also be noted that yellow, orange, or green level balls that are sold in bags are not pressurized. The bounce of these non-pressurized balls is determined by the wall thickness of the ball. Generally, these balls feel “harder” when hit and both inexperienced and experienced players alike can find the impact painful over time on their elbows. This is why non-pressurized yellow tennis balls are not very popular.
All this information raises the question: Is there something players can do to prolong the life of tennis balls?
YES! There is something you can do!!!! The first option is cost-free. Since heating the balls stimulates the movement of air molecules, energy is created and manifests with added air pressure. If you want to try out this idea, just put some balls in a clothes dryer for 30 minutes on high heat. See what it does. Experiment. You may find this helps extend the life of your balls in terms of the quality of the bounce. The felt may still wear down, but at least you won’t have to retire a ball that looks new but is totally flat with too little bounce to enjoy hitting with. The other option is to buy a tennis ball pressurizing machine like the ones from this company.
Where are tennis balls manufactured?
It is interesting to note that no tennis balls are made in the United States or Europe. Penn was the last dinosaur to go extinct about 15 years ago when they closed their tennis ball manufacturing plant in Phoenix, Arizona. Years ago, I remember touring that facility and it was fascinating to see the production methods! Now all tennis balls are made overseas in one of just a handful of factories in a few countries including China, Taiwan, and Malaysia.
Joe Dinoffer is a Master Professional in both the USPTA and PTR, has been recognized with numerous national awards including the 2019 City of Dallas Humanitarian Award for contributions to inner city tennis, and has conducted clinics and exhibitions in over 50 countries. Joe is the author and editor of 9 books and more than 20 DVDs, has more than 300 published articles in various tennis and pickleball magazines, and has aired many instructional tips on the Tennis Channel. Plus, Joe’s YouTube channel has more than 2 million views and growing! His latest book “Words, Wisdom, and Whimsy” is the second volume of an illustrated series called “Poems from the Heart.” In 1994, Joe founded OnCourt OffCourt, Ltd., a company dedicated to serving the tennis, pickleball, fitness, yoga, and physical education industries with innovative training aids and educational tools. Today, he has designed and manufactured more than 150 creative products being distributed and used in 100 countries worldwide.