How Tennis Balls Are Made?

 

A tennis ball is a ball designed for the sport of tennis. Tennis balls are fluorescent yellow at major sporting events, but in recreational play can be virtually any color. Tennis balls are covered in a fibrous felt which modifies their aerodynamic properties, and each has a white curvilinear oval covering it.

Modern 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 6.54–6.86 cm (2.57–2.70 inches). Balls must have masses in the range 56.0–59.4 g (1.98–2.10 ounces). Yellow and white are the only colors approved by the ITF, and most balls produced are a fluorescent yellow known as "optic yellow", first 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. The felt delays flow separation in the boundary layer which reduces aerodynamic drag and gives the ball better flight properties. 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.