The gold tennis ball has completed half a century of existence this year.
The so-called optical yellow is the official color of most of the 290 existing ball models, produced with the seal of 54 brands, approved by the International Tennis Federation (ITF) for the 2022 season.
Despite this, the white color remains in the catalog along with red, orange and green -conceived for initiation-, all accepted by the ITF. However, you can also find personalized and elaborate balls in pink, purple, black or different shades of blue on the market.
Now, originally and for a century, tennis balls were either white or black, depending on the playing surface.
It was in 1972 when competition white gave way to fluorescent yellow, essentially pushed by events broadcast on color television, surpassing the stage of black and white television.
It seems that a BBC broadcast manager (including Wimbledon at the end of the 1960s), and renowned documentarian such as David Attenborough, intervened in one of the first color broadcasts, where the visibility of the white ball was highlighted. , especially if it was close to the lines of the game rectangle.
With the sport including professional players and television giving greater coverage of tournaments, the ITF commissioned a study which found that the yellow ball was more visible and therefore easier for viewers to follow; reason why, in that 1972, the Federation approved a rule that contemplated that all the balls offered a uniform surface and of yellow or white color.
It is true that, as explained by the Argentine tennis historian Eduardo Puppo, other colors were tested in that study, but the conditions of the television image and the color of the different court surfaces made it necessary to guarantee a clear contrast. In this way, from 1972 it began to be played, experimentally, with yellow balls; although white balls continued to be used in official competitions in the following years.
Paradoxically, it was the Wimbledon organization that did not accept the change until 1986, despite the difficulties of visibility, maintaining until then the white balls in their tournament.
Thus, until the 1970s and for almost a century, the small tennis balls were generally white (off white or dirty white, rather), although, as we have already commented, there was the black variable to distinguish themselves. better on other surfaces.
The ball of our time practically stems from Lawn Tennis at the end of the 19th century, but before the game on grass, there was already a ball for playing the original game of the palm (jeu de paume) in France and Real Tennis in England, that they were practiced indoors, on both sides of the English Channel; as well as the American Court Tennis or the Australian Royal Tennis.
Until very recently, only one type of ball was contemplated for the game and the competition, but the ball did evolve in its construction.
What is a tennis ball like?
Initially, in the days of Real Tennis, they started from a spherical casing sewn from leather or cloth stuffed with rags, horsehair, tea and even human hair -legend has it that of the peasants who made them-; they were also made with cork. While tennis balls have always been based on rubber.
In the 1870s, coinciding with grass tennis, rubber from India, obtained through a vulcanization process invented by Charles Goodyear in the 1950s, was used to make balls that were lined with wool. As the rubber deteriorated with use, thanks to a kind of flannel sewn around the rubber core, the ball improved its performance and durability.
Already at the dawn of the 20th century, there was a change from those vulcanized rubber balls to those with a gas-pressurized hollow core, which were manufactured according to the cloverleaf principle, by which the uncured rubber sheet was stamped in a similar way. to a three-leaf clover and was assembled in a more or less spherical space. Before closing it, chemicals that produced the pressurized gas were added and activated by molding the core into the sphere in heated cavities.
The process was useful for many years, but playing precision required more uniformity in the sphere, especially in terms of wall thickness, so the cloverleaf gave way to two compression-molded half-shells, which were They were assembled to create the rubber core covered with a melton type fabric (high quality wool) -produced specifically to replace the original flannel-, with a vulcanized rubber seam.
Thus, today, the core of pressurized balls generally starts from natural rubber (72 parts by weight) with a high filler load of fine particles -such as clay (40), butadiene rubber (28), carbonate of calcium (20), magnesium carbonate (8), sulfur (3.5) and zinc oxide (2.5)- to achieve low gas permeability.
As for rubber, and following the origins of Goodyear, for example, Dunlop uses its experience in the world of tires (since the 1920s) to manufacture the cores of its balls, just as Tecnifibre uses natural rubber together with to another reputable wheel company, Bridgestone.
To inflate the balls, the industry uses chemicals such as sodium nitrite and ammonium chloride, which produce nitrogen, or by using compressed air. There are manufacturers that use the composition of natural air in the pressurization of their balls (78% nitrogen, 21% oxygen and 1% argon, carbon dioxide and some other gas).
For the lining of the ball, two types are usually used: melton cloth, with a greater amount of wool, and needle cloth, with a higher content of synthetic fibers and more economical. Hence the difference between premium and championship balls.
They are considered premium due to the greater use of natural fibers or the combination of wool and synthetic nylon fibers -sometimes cotton appears-, which is synonymous with durability, resistance, consistency, good touch and longer pressure maintenance; while the championship type is based more on nylon fibers -less natural wool- or on the so-called needle-punched felt (common in thermal and acoustic insulation). For a more basic level, one hundred percent synthetic felt is used, as in depressurized balls.
Approved Spherical Types
The almost three hundred models of balls approved by the ITF for 2022 are manufactured mostly in Thailand, the Philippines, China and Taiwan, and even in Argentina, Brazil, Indonesia and Italy.
Until the so-called altitude balls were introduced, in the 1989 regulations, only one type of tennis ball was allowed.
Currently, there are eight types. Beyond the balls for initiation, such as those of the so-called stage 3, red foam and standard red (red and yellow), stage 2 -orange and yellow- and stage 1 -green and yellow-, and the depressurized; there are those classified by the ITF as type 1 or fast, designed for slow surfaces such as clay; type 2 or medium, pressurized or depressurized, designed for all types of surfaces, such as semi-fast cement or indoor courts; type 3 or slow, with a larger diameter than the previous ones, intended for very fast tracks such as grass; and those of high altitude, for competitions above 1,219 meters (4,000 feet), of which thirteen models of eight brands have been approved.
Type 1 and 3 balls were introduced into the regulations just twenty years ago (2002).
For the classification of these spherical balls capable of flying at 250 kilometers per hour and that can rotate at more than 5,000 revolutions per minute, the International Tennis Federation considers, in previous tests, measurement, weight, pressure, rebound, deformation, aerodynamics, speed, stamina, or durability; depending on the playing surfaces, speed and altitude, temperature, humidity and atmospheric pressure.
Today’s ball weighs between 56 and 59.4 grams and its diameter is between 6.54 and 6.86 centimeters (for type 1, 2 and altitude), between 7 and 7.3 cm for type 3; and your boat must be between 1.35 and 1.47 meters when it falls from a height of 2.54 meters.
In the 21st century, and when production figures for balls of 500 million a year have already been exceeded – among the four grand slam tournaments, consumption is around an average of 250,000 units per year, being about 160,000 among the eight masters 1000 of this season-, the concern lies in the recycling of these balls -which only in Spain are around 10 million units per campaign, between tennis and paddle tennis-, whose materials could take more than two thousand years to decompose.
In this regard, several ingenious people have worked and evolved on their pressurizing devices for some years now, such as the Ball Rescuer or PressureBall, which make it possible to maintain and recover the pressure of the ball, extending its life by up to six and ten times, preserving its capacity to bounce until the felt wears down.
The Head company has recently launched four types of pressurizers: X3 Black and X3 Pump, for 3 balls, X4 Pump, for four, and X100 Basket, for up to 103 balls; the last three not only keep the pressure up, but they recover it.
The balls that are recycled, without leaving our country, contribute to the soundproofing of spaces, to the construction of rubber-based playing surfaces (Roland Garros, for example, within its ‘yellow ball’ program, reuses those used during the tournament for the construction of court surfaces) or the manufacture of clothing and footwear, such as the initiative of the company No Time, whose young founders collect the small balls from the tennis and paddle tennis courts in Madrid, send them to be crushed and then produced shoes in collaboration with Fundación A La Par, where people with intellectual disabilities work.