The specifications of a golf ball are determined by the United States Golf Association and the R&A; of St. Andrews, Scotland -- the governing bodies of golf. The ball must not weigh more than 1.62 ounces or be smaller than 1.68 inches. There are no rules that specify how light or large the ball can be. Both the USGA and the R&A; limit the maximum initial velocity of the ball and how far it may fly and then carry after it hits the ground. Golf balls are composed of two, three or four pieces.
The core of a two-piece ball is molded under heat to the manufacturer's specifications. The core is made of gel, liquid or a solid/synthetic rubber. Different manufacturers use different substances. The core must be perfectly spherical.
After the core has been molded, the outer casing of a two-piece ball is applied through an injection molding process. The outer casing is surlyn for two-piece golf balls. Surlyn is harder and more resistant to scuffs and cuts than the softer urethane covers of three- and four-piece balls.
A golf ball's dimples are formed by a mold. But the dimples aren't just there for looks. A golf ball in flight creates friction as it passes through the air. A smooth ball would create more drag than a dimpled ball, which separates the air later in flight, causing it to travel farther. According to "The Golf Book," a golfer hitting the ball with a driver would get 150 yards more carry with a dimpled ball than with a smooth-surface ball. Most golf balls have 300 to 450 dimples.
Smoothing, Painting and Finishing
After the ball has been covered with an outer casing, the seams are smoothed. The ball is then spray painted and logo stamped. There are no restrictions on what color the ball can be. The USGA's 2012 Golf Ball Conformance Submission Guidelines specify that the "use of iridescent paint is strongly discouraged." After a clear coat is applied, the ball is dried and packaged. Two-piece balls are measured for conformity to size and roundness. Two-piece balls also are X-rayed to ensure the core retains its spherical shape.
Three- and Four-Piece Balls
Three- and four-piece balls are manufactured differently than two-piece balls. More than 80 steps and 32 inspections are involved. Three-piece balls have a third covering of enhanced rubber over the inner core. The core covering can be solid or wrapped rubber string. The core covering's job is to transfer the velocity of the club striking the ball to the inner core. Four-piece balls have an additional middle casing midway between the ball's soft center and the hard outer casing. The outer casing is usually made of urethane, which is softer than surlyn. The two outer casing halves are fused to the third and fourth casings and the core by compression molding and heat.