20 Things You Never Knew About Tennis Balls

	The first tennis balls were made from leather pouches stuffed with human or animal hair.
	Vulcanised rubber was first used to manufacture tennis balls in 1870.
	Yellow-green tennis balls were introduced into the sport as recently as 1972. Prior to this all tennis balls had been either black or white depending on the background colour of the court.
	The current colour used for the production of tennis balls is known as ‘Optic Yellow’, and has been proven to be the second most visible ball colour for all the different surfaces and conditions.
	If tennis ball design specifications were based purely on scientific considerations, orange balls would be used under certain conditions. The fact that these balls are less visible on television has prevented orange balls from being adopted for certain surfaces.
	Three types of tennis balls are used for professional tennis matches, with different balls used on clay, lawn, carpet and hard court surfaces. Prior to 2002 only one type of ball had been used on all surfaces.
	9 out of 10 tennis balls are produced in Asia, where rubber, the main ingredient in tennis ball production, is naturally abundant.
	Hollow core tennis balls were initially pressurised by adding chemicals to the interior of the ball prior to sealing. Heat was then used to activate these chemicals and pressurise the ball.
	Modern tennis balls are pressurised when the two halves of the ball are joined in a compression chamber.
	The most expensive material used in the production of the tennis ball is the felt covering. The felt is ‘melted’ onto the ball during production, and plays a crucial role in the flight and wind resistance of the ball.
	300 million tennis balls are manufactured every year.
	Because tennis balls are not easily recycled, alternative uses were identified for these balls. In England used tennis balls from major tournaments are put into service as habitats for the endangered field mouse.
	Quality tennis balls are stored in pressurised canisters prior to sale and use. Balls start losing pressure from the moment the canister is opened, but can be rehabilitated in special re-pressurising chambers.
	The pressure in a match quality ball is approximately 2 atmospheres.
	ITF approved tennis balls must weight between 56.7 grams and 58.5 grams. Ball diameter must be between 63.5mm and 66.7mm.
	Over 200 tennis ball brands have been quality assured by the International Tennis Federation.
	Some tennis players prefer to use non-pressurised balls that become lighter and more aerodynamic the longer they are kept in play.
	Rubber core tennis balls are still in production and are used to play Real Tennis, the predecessor to modern ‘lawn’ tennis.
	Regular tennis balls are not suitable for use as toys for dogs as the dye used in production is carcinogenic. Special tennis balls are specifically designed as toys for dogs.
	The colour of the print used to brand tennis balls is determined by the surface it will be used on. Red print balls are used on clay courts while black print balls are used on hard courts.