Ping pong balls are small, lightweight, usually celluloid balls used in playing ping pong or table tennis. Ping pong balls come in various sizes, densities and colors. Regulation sized balls come with a one, two or three star quality ratings, exact diameter, weight and specific flight and bounce characteristics.
The first ping pong balls were air-filled spheres made of latex and used in variety of informal games like whiff-whaff and gossima. In 1880, James Gibb invented the modern hollow celluloid ping pong ball. In 1903, J. Jacques and Sons rechristened gossima, calling it ping pong, starting a craze for the game that swept England and then the world. The new celluloid ball's more consistent bounce and flight characteristics allowed the game to develop into a legitimate sport based on skill and without the vagaries of the earlier, more irregular latex ball.
Regulation ping pong balls by international rules must weigh 2.7 grams and have a diameter of 40 millimeters. When dropped from a height of 30 cm onto the table, the ping pong ball must bounce 23 centimeters high. The ball must be white or orange, the choice depending on the color of the table. Regulation balls must be quality rated at three stars.
Most ping pong balls used to be 38 millimeters in diameter until after the 2000 Olympics when the international rules were changed in favor of the larger ball. This was done to improve visibility for television cameras following the competition. The new ball was first introduced at the 2003 World Table Tennis Championships. The larger ball slowed the game so spectators could follow the ball. The Chinese team, whose members had developed a blazing fast style of play, protested that the change was discriminatory to their players. The 40 millimeter ball has remained the standard size, though serious attempts have been made to increase ball size to 44 millimeters.
A ping pong ball is filled with gas to improve bounce, is colored white or orange and has a matte finish. This makes the ball slower and reduces the spin speed from the older 38 millimeter ball. The matte finish allows the table tennis bat face to grip the ball better. An adept player can apply lateral force to the ball and cause it to spin at up to 9,000 rotations per minute. This high rate of spin creates the so-called Magnus effect, which causes the lightweight ball to execute spectacular curves in flight, adding a dimension to the game not otherwise possible.
Ping pong balls don't flex when they strike a hard surface. The struck surface absorbs much of the energy limiting the bounce of the ball, making ping pong a more playable game than it would be with a livelier ball with a flexible shell that pushed back when struck. This rigidity accounts for the ping pong ball's tendency to break when struck very hard. In ping pong smash exhibitions players have volleyed balls at more than 112 kilometers per hour with a 38 millimeter ball.
All regulation size table tennis balls are quality rated either one, two or three stars. Three stars is the highest rating and are the only balls used in competition. They tend to be rather more fragile and subject to breakage than the one or two star balls, and many ranked players use the lower quality balls for practice. Lower quality balls also may have some irregularities which effect the flight qualities. Many players believe these imperfections help them develop faster reaction times. Others prefer to use the exact ball they will use in competition. The star rating merely helps buyers more effectively choose the characteristics they value most in a ball.