Most sports balls have a distinctive color – footballs are brown, basketballs are orange, soccer balls are black and white, etc. Per the reel we posted last month, in response to a fan asking him the question, “Are tennis balls green or yellow?” Roger Federer replied “Yellow, right?” If Roger, the GOAT, says they’re yellow, then we’ll go ahead and roll with that. Tennis balls have not always been the bright yellow color that we all recognize and love. If you are an avid tennis historian, you may recall that they actually used to be white! But did you know that back in the old days you could also find them in black? Let’s walk through the history of the color of tennis balls and how they’re made – because the process, whether in the olden days or newer age, may surprise you.
Original Tennis Ball in Black (bottom right)
Tennis balls are made with vulcanized rubber. Vulcanization is a process that involves adding sulfur to rubber and heating it at ~300 degrees Fahrenheit (150 Celsius) to improve its elasticity and strength. As you can see below, vulcanization machines are quite large. The sulfur-treated rubber pellets are placed into semi-spherical slots, and upon completion of the process, the rubber adopts the shape of a tennis ball.
Rubber Pellets Pre-Vulcanization
Rubber Pellets Post-Vulcanization
In modern times, tennis balls are constructed by taking two of the molds pictured above and gluing them together with a natural rubber adhesive. However, in the early days, when the game demanded less precision, manufacturers used the “clover leaf method.” This process was done through taking a piece of rubber that looks like a 3-leaf clover and forming it into a roughly spherical shape. Tennis is a tough sport as is – imagine playing with a ball that isn’t even perfectly round!
The last step of making a tennis ball is covering the hollow, vulcanized rubber sphere with felt and then pressurizing it. In the old days, the felt was either undyed (white) or dyed black, depending on the background color of the court. If the court was lighter, a black ball would be used, and if the court was darker, a white ball would be used.
Original Tennis Ball in White
Today, you can still generally find white balls, especially at clubs with grass courts, like the West Side Tennis Club in Queens, NY. While they're not commonly used, they do look pretty cool:
Modern Day White Tennis Balls
In 1972, the International Tennis Federation (ITF) introduced a rule demanding that the felt must be dyed yellow, specifically “optic yellow.” This reason behind this shift can be traced to the 1960s, when David Attenborough, the controller of BBC2 at the time, was tasked with making the audacious pivot from black-and-white TV to color TV. He suggested a fluorescent yellow tennis ball to create contrast and improve visibility – the rest is history! Take a look at how the modern-day tennis ball gets its distinctive color below:
Felt Sheet Being Cut into Strips
The felt is cut into oval-esque shapes (above) before two pieces are attached to the rubber ball as such:
How Felt Strips are Attached to Ball
As you can see, tennis balls have a bit more history than you’d probably expect. Imagine how different the sport would be if Attenborough hated yellow and decided to suggest a bright orange ball instead. Let us know what you learned in the comments down below and be sure to fill out the poll so we can officially put this debate to rest.
What Color are Tennis Balls?
Green
Yellow
Works Cited
Air pressure. National Oceanic and Atmospheric Administration. (n.d.). https://www.noaa.gov/jetstream/atmosphere/air-pressure
Diadem premier white grass court ball - can. Diadem Sports. (n.d.). https://diademsports.com/products/diadem-premier-white-grass-court-ball-can
History of tennis balls. (n.d.). https://www.itftennis.com/media/2280/balls-history-of-tennis-balls.pdf
How It’s Made, & Tech Machine. (n.d.). Inside a Tennis Ball Factory: From Rubber to Felt. YouTube. https://www.youtube.com/watch?v=AmBJ0dzMr1c
Lang, R. (n.d.). The History of Tennis Balls. The history of tennis balls. https://www.tennisplayer.net/public/notes_on_tour/rocky_lang/the_history_of_tennis_balls/?public=true
M., F. (2024, May 22). The event that caused tennis balls to turn yellow: What color were they before?. MARCA. https://www.marca.com/en/tennis/roland-garros-/2024/05/22/664dc4c222601d0a4e8b45c8.html
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