Tennis ball:
A tennis ball is a ball designed for the sport of tennis, approximately 6.7 cm (2.7 in.) in diameter and is normally yellow in color.
Modern balls:
Modern balls are made from rubber mixed with 14 to 18 chemicals to get the proper consistency. Approximately 85% of the ball weight is the rubber/chemical mix. Over 90% of tennis balls are produced in Southeast Asia where the natural resource is abundant. The most expensive ingredient in the ball is the felt, which is adjusted in various ways to produce different properties. Steaming the felt raises its nap to make it fluffier, which increases wind resistance and control (through increased resistance when striking the players' rackets) while reducing bounce and speed. A compact nap causes the ball to skip on hitting the court or a racket.
Modern balls are made from rubber mixed with 14 to 18 chemicals to get the proper consistency. Approximately 85% of the ball weight is the rubber/chemical mix. Over 90% of tennis balls are produced in Southeast Asia where the natural resource is abundant. The most expensive ingredient in the ball is the felt, which is adjusted in various ways to produce different properties. Steaming the felt raises its nap to make it fluffier, which increases wind resistance and control (through increased resistance when striking the players' rackets) while reducing bounce and speed. A compact nap causes the ball to skip on hitting the court or a racket.
Pressure-less balls:
Pressure-less balls usually have a stiffer, woodier feel than pressurized balls, and except for the Tretorn brand, do not bounce as high as brand new pressurized balls. Unlike pressurized balls, though, they do not lose bounce over time. In fact, they get bouncier as they get lighter, due to fuzz loss. The balder they get, the more their flight, bounce, and spin response changes from what you would expect of tennis balls.
Pressure-less balls usually have a stiffer, woodier feel than pressurized balls, and except for the Tretorn brand, do not bounce as high as brand new pressurized balls. Unlike pressurized balls, though, they do not lose bounce over time. In fact, they get bouncier as they get lighter, due to fuzz loss. The balder they get, the more their flight, bounce, and spin response changes from what you would expect of tennis balls.
Standardisation:
Brand new yellow tennis ball on the left, with a used ball, duller and greener in color, on the right
Tennis balls must conform to certain criteria for size, weight, deformation, and bounce criteria to be approved for regulation play. The International Tennis Federation (ITF) defines the official diameter as 65.41-68.58 mm (2.575-2.700 inches). Balls must weigh between 56.0g and 59.4g (1.975-2.095 ounces). Yellow and white are the only colors approved by the United States Tennis Association (USTA) and ITF, and most balls produced are fluorescent yellow (known as "optic yellow") the color first being introduced in 1972 following research demonstrating they were more visible on television. Tennis balls are filled with air and are surfaced by a uniform felt-covered rubber compound. Often the balls will have a number on them in addition to the brand name. This helps distinguish one set of balls from another of the same brand on an adjacent court.
Brand new yellow tennis ball on the left, with a used ball, duller and greener in color, on the right
Tennis balls must conform to certain criteria for size, weight, deformation, and bounce criteria to be approved for regulation play. The International Tennis Federation (ITF) defines the official diameter as 65.41-68.58 mm (2.575-2.700 inches). Balls must weigh between 56.0g and 59.4g (1.975-2.095 ounces). Yellow and white are the only colors approved by the United States Tennis Association (USTA) and ITF, and most balls produced are fluorescent yellow (known as "optic yellow") the color first being introduced in 1972 following research demonstrating they were more visible on television. Tennis balls are filled with air and are surfaced by a uniform felt-covered rubber compound. Often the balls will have a number on them in addition to the brand name. This helps distinguish one set of balls from another of the same brand on an adjacent court.
Tennis balls begin to lose their bounce as soon as the tennis ball can is opened and can be tested to determine their bounce. A ball is tested for bounce by dropping it from a height of 100 inches (2.5 m) onto concrete; a bounce between 53 and 58 inches (1.35 - 1.47 m) is acceptable (if taking place at sea-level and 20°C / 68°F; high-altitude balls have different characteristics when tested at sea-level). Modern regulation tennis balls are kept under pressure (approximately two atmospheres) until initially used.
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