TENNIS BALL

History

The very first tennis balls date back as early as the 15th century and were made of different materials, mostly from leather stuffed with human and horse hair or wool. The Scottish craftsmen used the stomach of a sheep or goat that they wrapped with wool and tied with a rope. In the 18th century, strips of wool were tightly wound round a nucleus made of cork. Tennis balls with a cork core and cloth covering are still used in the original game of tennis, known as Real Tennis.

Modern composition

In 1870, vulcanized rubber was first used to manufacture tennis balls. The Germans were well known for developing vulcanized air filled rubber balls. Constant improvements were being made to the ball, by wrapping flannel around their surfaces and later using a felt on the exterior. Pressurized tennis balls started to be manufactured, and are being used today.

Around 300 million tennis balls are produced each year. The most expensive material when manufacturing a tennis ball is the felt covering the ball. There are more than 200 tennis ball brands that have been approved by the ITF. Standardization approved by International Tennis Federation :-
- Size – the diameter of a tennis balls is 6.35-6.86 cm (2.50-2.70 inches)

- Weight – must be between 56.0 g – 59.4 g (1.975 -2.095 ounces)
- Rebound Height – between 135-147 cm (53-58 inches)
- ATP and WTA tournaments are played with yellow tennis balls, that were introduced in 1972 following research that demonstrated their easy visibily on colour television. White balls were used prior to this.

All tennis balls are tested in the following environment:
- Tempereature 20°C / 68°F
- Humidity 60%
- Atmospheric pressure 102 kPA

Production

Tennis ball manufacturers mold rubber into two shapes that are pressed together to form the core of a ball. To achieve an appropriate level of bounciness, tennis ball makers inject a specific amount of pressurized air into the center of each rubber core. Manufacturers buff the sealed, pressurized rubber balls and cover them in glue. Machines cut long pieces of bright yellow felt into two shapes that are wrapped around each tennis ball to form a covering. Ball makers heat the completed tennis balls to make the glue form a seal that holds the two pieces of fabric together.

Why tennis ball bounces?

The anatomy of a tennis ball features a hollow rubber-like core filled with gas. The molecules that make up gas are relatively unorganized; they readily slide around and over one another to fill up any space they occupy. As such, gas molecules can easily expand or contract. When a tennis ball hits the ground, the force presses up against the ball, pushing the bottom surface of the ball in and compressing the gas inside its core. As the tennis ball returns to its normal shape, the gas inside the ball acts as a spring and causes the ball to bounce into the air.

Amazing uses

• Keep a swimming pool oil-free - Float a couple of tennis ball sin your swimming pool to absorb body oil from swimmers. Replace the balls every couple of weeks during period of high use.
• Fluff down-filled clothes - Down filled items like jackets, vests, quilts, and pillows get flat and soggy when you wash them. You can fluff them again by tossing a couple of tennis balls into the dryer when you put them in.
• Make a bike kickstand for soft soil - to prevent a bicycle kickstand from sinking into soft grass, sand or mud, cut a slit in a tennis ball and put it on the end of the kickstand.
• Tennis balls are actually pretty difficult to recycle and most go to their 2^nd life as anti-scuff devices on the bottom of chair legs.  However, the balls from Wimbledon are used as homes for the endangered Eurasian harvest mouse.  Other uses include covering it in vasoline and hanging it outside to deter bugs, cutting them open and hiding things in them.