Judging the Spin from an Antispin Rubber
By Bill Lui, U.S. National Junior Girls Coach
Mar. 22, 2004

Most players, when asked the question, how does a ball behave when struck by an antispin rubber, will answer one of two ways:

It reverses the spin, or it kills the spin and the ball comes back like a knuckle ball

Even though both of these conditions occur frequently in actual rallies, these statements are misleading. In order to clarify this, we must understand how an antispin rubber works.

All antispin rubbers have one characteristic in common, their surfaces are very slick, they do not grip the ball very much when they make contact with it. Then why is it that the spin can be reversed when struck by the antispin rubber? The reason is that since the antispin rubber does not grip the ball, the spin on the ball continues to rotate in the same direction when struck by the antispin rubber. After the ball is struck, the flight of the ball is now going in the opposite direction. To the opposing player who originally strikes the ball, the spin is now reversed. The spin is not actually reversed. It is the direction of travel of the ball that has been reversed. The ball is spinning the same way but traveling in the opposite direction. Thus a ball going away from the "regular" racket with topspin spinning in the same direction when it comes back now has backspin and vice versa. When the ball has no spin to start with, there is no spin when it comes back when struck by an ant ispin rubber. The best way to demonstrate this is to take a ball, draw a line around its circumference and observe the rotation of the ball by simulating a constant rotation going away and coming back to a player. I use a 4 inch Styrofoam ball on the end of a stick with a black tape around the circumference as a visual aid when illustrating this effect to my students.

After we understand how the spin can be "reversed" by an antispin rubber we can examine the reason why "it kills the spin and the ball comes back like a knuckle ball" when it does not grip the ball very much and thus cannot stop the ball from spinning. When a regular racket surface imparts spin on the ball, it is spinning the fastest when it leaves the racket. As soon as it leaves the racket, the rotation rate is slowed down by friction against the air, contact with the table, contact with the anitspin rubber (even though it does not grip the ball very much), against the air on the way back, and then contact with the table again before being struck. If the ball is not spinning very fast to start with when leaving the "regular" rubber, so much rotation is lost to the point that very little spin is left and a knuckle ball effect occurs by the time the ball reaches the "regular" racket again.

Once we understand the principle behind these common occurrences, we can better judge the spin that is coming back to us when the ball is struck by an antispin rubber. The motto is: know the spin (and how much) that you are putting on the ball when you strike the ball and you can correctly predict the spin that is coming back to you when struck by an antispin rubber.