Sphere Of Influence: How Tennis Balls Differ At The Slams

by: Tim Newcomb | September 05, 2017

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Professional players seemingly touch every tennis ball a ballperson has to offer, giving each a once-over of examination before relegating some away from the court of play, dropping a second choice into a pocket and sending the favored ball straight into service.

This dance is more than ritual, as it has performance attributes rooted right in. While the International Tennis Federation oversees the official balls, allowing an accepted size and weight for balls to fall in, with the diameter hovering between 2.57 and 2.70 inches and weighing between 1.975 and 2.095 ounces, each manufacturer can choose their own felt makeup and weaves, often a nylon-wool blend. Balls switched away from flannel to the wool-nylon felt to improve the aerodynamic properties and to regulate speed and bounce. Plus, felt provides ample surface for racquets to grab the ball for additional spin.

That felt changes during the course of play and players may search for the feel they believe gives them the best advantage, such as a less fluffed version for speed in the air or a highly-fluffed version to sit on the racquet just a smidge longer for increased spin.

As players move from tournament to tournament they encounter differing ball construction. The Grand Slams don’t stray from that trend, with three different manufacturers handling the four tournaments. Players shift from hard courts to the clay season, to grass and back to hard again at the US Open.

Each ball has its own purpose on the specific surface, as lighter felt can wear quickly on a hard court and really speed up the game—too much for the men at the U.S. Open, for example, meaning they use a more durable felt—but the hard-court felt in play on a soft surface won’t wear the felt away, instead fluffing it up extraneously. On clay, this extra fluff can pick up debris along the way, changing the feel and play of the ball. Hard court balls typically opt for a heavy-duty felt in a looser weave for durability, while the softer surfaces move toward a tighter weave, which fluffs quicker.

Wilson, which also manufacturers the ball used at the Australian Open, will create roughly 100,000 balls for use in New York, but they won’t all be the same. While the size, pressure and look may match, Wilson uses two different felts for the tournament, an extra-duty variety for the men and a more traditional regular-duty felt for the women. The extra-duty Wilson ball for men have more felt to help slow down the men’s game, while a bit less felt on the women’s ball will speed it up.

As a ball wears down, the fluffing of the felt makes the ball larger in size, slowing it down in the air and creating a larger bounce. The hard-court varieties of Wilson come in the higher range of diameter, but with less felt for a different feel for the players.

Slazenger, known for being a heavy ball and the provider of Wimbledon balls since 1902, includes a water-repellent barrier dubbed Hydrogruard to protect it from rain and moisture in the air. A heavier ball doesn’t bounce as high and with lower air pressure requires more pop from the player to produce pace.

Babolat, which has handled duties in Paris at Roland Garros since 2011, has adopted a clay felt that wouldn’t stand up to a hard court, but allows for a high-rebound off the clay, says a company spokesperson. The French Open ball hasn’t changed in four years.

Under the felt, which differs in its cross-weave, comes the vulcanized rubber, susceptible to heat, making a ball bounce more in the heat than, for example, in a cooler night match under the lights on Arthur Ashe Stadium. A bit too much humidity can make the ball heavier in the thick air.

At the Grand Slams, matches see new balls every nine games (after the first switch following game seven). In a twist, the balls for Wimbledon get opened each morning and then placed in a refrigerator courtside at 68 degrees Fahrenheit for ideal conditions, while the U.S. Open balls get opened on court as they come into play. In Paris, where the felt attracts a slight bit of dust as it plays, new balls come clean too, an added bonus.

While the differences may prove slight, professional players can obsess about the smallest of details that change their gameplay. Finding the right amount of fluff for the next ball to put into play proves an exacting process. Thankfully the ballperson is there to clean up the rejected felt.


Tim Newcomb covers sneakers for Tennis Magazine and tennis.com. Follow him on Twitter at @tdnewcomb

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