Characteristics of Rubber Basketballs

The cover of a basketball determines whether or not a ball is a rubber basketball because all basketball interiors are made from rubber. The first basketball was made in 1894 in Europe but since then, many variations of the original have been made to improve the game. Specifically, two ingenious designs have been introduced to improve grip. The "Hole in One" ball has golf ball-like dimples. Another design incorporates polyurethane microscopic holes for perspiration absorption.

  1. Dimensions

    • Rubber basketballs have an average circumference ranging from 28 1/2 to 31 inches. Balls for men or players with large hands are on the higher end of the diameter spectrum while those used by adult women's teams usually measure 28.5 inches around. Depending on size, the average rubber basketball weighs between 18 and 22 ounces. Rubber balls are used by professional teams for outdoor use. Indoor court games require leather balls.

    Quality

    • The quality and cost of rubber basketballs are determined by the threading used to hold them together. Balls used by professional basketball teams are of the highest quality, sewn together with quadruple strands of nylon thread. Cheaper balls available to the average consumer are made from triple strands of polyester. Threads literally build and shape rubber basketballs. Rubber basketball quality is also controlled for inflation air pressure by a bounce test. Balls that pass the test bounce up to a designated height.

    Exterior

    • The covers of rubber basketballs are crafted from sheets of smooth, colored rubber. Punch presses create six rubber panels for one ball. The panels are then coated in glue and placed into a vulcanizer different from the one used on the bladder. It creates channels and embossments on the exterior. Any gaps in the panels are filled in with additional rubber after the first vulcanization. A third vulcanizer is then used to smooth the surface and mold the ball to create the pebbled surface that is familiar to basketball players.

    Interior

    • The interiors of rubber basketballs are called bladders. Butyl rubber is pressed into a sheet 12 inches wide and 1/2 inch thick. Butyl rubber sheets are then cut into strips that are 18 inches long and one-inch holes are punch-pressed into them for air tube insertion. Before the ball is inflated, however, the bladders undergo heat treatment also known as vulcanization. Vulcanization makes the rubber stronger and sturdier, and adds flexibility. It also inflates the bladders, seals the rubber and allows for inflation quality control.