Early soccer balls were hand-sewn and made of leather. They were never perfectly round, and inflating them required some skill. The laces had to be undone before an interior air bladder was filled and tied with a thread; then the laces were retied.
Team captains chose a ball before each match, and every team had a preferred design, according to Peter Pesti, a collector and expert on World Cup balls. In the first World Cup, in 1930, Uruguay and Argentina could not agree on which ball to use. The first half of the match was played with a model favored by Argentina. The second half was played with Uruguay’s preferred design, the T-Model. Argentina led, 2-1, after the first half, but Uruguay recovered in the second and won, 4-2.
The heavy leather laces of early balls made headers potentially painful, and relatively rare. A later innovation in valve design eliminated the laces. The new balls were much easier to head, and they held their shape better.
The 1970 World Cup was broadcast by satellite in both Europe and the Americas, and the Telstar Durlast was designed to be television friendly. The enduring black-and-white pattern was said to improve visibility on black-and-white sets.
The construction of the ball was innovative as well. Older balls, with horizontal and vertical stripes, resembled volleyballs. Adi Dassler, a founder of Adidas, broke away by choosing a 32-panel design that made the ball more spherical, allowing for improved ball control.
The new construction set the standard for the next three decades of World Cup balls, with leather eventually giving way to synthetics. Meanwhile, Adidas has provided the ball for every tournament since 1970.
The newest balls are heat-sealed, with fewer panels and a more aerodynamic seam pattern. Though these balls were designed to perform more uniformly, the Jabulani design was harshly criticized at the 2010 World Cup. Many players complained that the ball’s trajectory was fickle and unpredictable.
Adidas has said that this year’s ball, the Brazuca, has gone through rigorous testing in advance of the tournament.