The Rules of Tennis
There are specifications for ball durability codified in the ITF Rules of Tennis. The durability requirements are provided in an unnumbered table in Appendix I. There are conformance parameters for mass, rebound, forward deformation, and return deformation. The durability testing performed by the ITF uses laboratory equipment that simulates nine games of play.
The ITF testing procedure consists of “projecting” a ball for 20 impacts at a specified angle and rate of speed and spin. Two balls are then placed in a felt-wearing device for a period of 2 minutes. The felt wearing device is a box lined with medium grade emery paper with three spigots that cause the box to rotate. There is a much longer explanation for the testing that is performed in the ITF Technical Manual. [2]
When a manufacturer submits a tennis ball for testing, six balls are selected at random for durability testing. Once all the other testing is completed, the six selected balls are visually inspected for felt wearing, cracks, and ruptures. Those balls are then tested against the durability parameters outlined in Appendix I.
I think what the tennis consumer would really want to know is how various manufacturer’s balls stack up against each other in terms of durability. Back in 2007 Racquet Sports Industry magazine carried an article that described ball testing in detail, and produced labeled comparison graphs of ball performance for several identified major manufacturers. The charts are a little low in resolution, but the information is fascinating. There is a link to that article in the reference list at the end of this post.
The durability test used in that study was described by the authors as follows:
The durability test involved firing each ball 30 times at high speed and oblique angle onto a cutout slab of hardcourt. The ball hit the fence and was returned to the ball machine via one bounce on the tennis court.
Excerpt from Ball Testing, Rod Cross and Crawford Lindsey, Racquet Sports Industry Magazine, July 2007.
While that study didn’t assess the durability of the felt, it did reveal that many tennis balls actually bounce higher after they have been used for a short time. Durability can be regarded as a measure of the consistency of performance parameters of the balls after usage. Some balls performed better than others in each dimension. There was not clear cut “best” or most “durable” ball.
Usually the selection of the ball is outside of the control of the player. However in USTA League play, the home team generally supplies the balls. The balls have to be USTA/ITF approved, but as long as they are a player or team could select a ball that is best tailored to their game.
For example, playing low balls is a strength of my game and is something that I usually do better than my opponent. If I wanted to overthink it, which… is the hallmark of this site, I should try to play league matches with the lowest bouncing ball out of the can as possible. In 2007 that would have been the Wilson Extra Duty or the Penn Extra Duty ball.
The highest bounce height for new balls straight out of the can was measured to be Prince Tour Regular Duty. Second on the list was Dunlop Championship Hard Court Balls. In one of the earliest posts on this site, “How to Make a Tennis Ball,” I divulged the following:
True confession time: there is one brand of ball that I loathe to the point that I once intentionally dispatched one of the balls over the fence and then magnanimously opened a new can of the ball that I prefer for the remainder of the match.
Excerpt from “How to Make a Tennis Ball” January 17, 2020
I am now prepared to identify that the ball in question during that match was a Dunlop Championship Hard Court Ball. It bounces too damn high. The can I opened was a Pro Penn Marathon Extra Duty ball.
- United States Tennis Association (2021), Friend at Court: Handbook of Rules and Regulations, White Plains, NY
- ITF Approved Tennis Balls, Classified Surfaces & Recognised Courts, ITF, 2021.
- Ball Testing, Rod Cross and Crawford Lindsey, Racquet Sports Industry Magazine, July 2007.
