The materials that make up golf balls have evolved through the long and fascinating history of golf. Historically, these materials were linked to natural compounds, all of which were derived from objects in nature, particularly different species of trees.
The Scots, who originated the game in the 1400s, developed a variety of golf clubs: irons, putters, and woods. Woods are the longest clubs in the bag and are mostly used for long shots. The wood heads were made of persimmon (Diospyros) or maple (Acer) trees. The introduction of golf into America in the early 1800s led to the use of hickory (Carya) (native to the United States, but not to the United Kingdom) in the shafts of the clubs. These clubs were far stronger than other woods and became standard until steel shafts were introduced in 1925.
The first balls – called “featheries” – were leather-covered objects stuffed with boiled goose or chicken feathers., and then coated with paint. Feathers were first boiled and then placed in the pouch. As the ball cooled, the feathers would expand and the hide would shrink, making the hard, compact ball that would fly far and accurately.
Later, tree products entered into the golf ball. The “gutta-percha” ball was created in 1848. Gutta-percha is the evaporated milky latex from Malaysian Sapodillo tree of eastern Asia, Palaquium gutta. This and other related trees, such as the “bully tree” (Manilkara bidentata) of the West Indies, yield a hard rubber-like material called “balata.” Trees are tapped by cutting zigzag gashes in the bark, something like the harvest of maple sap to make maple syrup. The latex was collected in cups that hung from the trunk. That raw material turns into a tough, resilient, and water-resistant material.
The rubber was made round by heating and shaping it while hot. However, since the ball was spherical, it creating little lift and went only short distances. Accidentally, it was discovered that defects in the sphere from knicks and scrapes of normal use could provide a ball with a truer flight than a pure sphere. Thus, makers started creating intentional defects in the surface by hammering the ball to give it an evenly “dimpled” surface, which caused the ball to have a more consistent ball flight. Because gutties were cheaper to produce and could be manufactured with textured surfaces to improve their aerodynamic qualities, they replaced feather balls completely within a few years.
The most common dimple patterns are the icosahedral, the dodecahedral, and the octahedral. The icosahedral pattern is based on a polyhedral with 20 identical triangular faces, much like a 20-sided die. Similarly, a dodecahedral is based on a polyhedral with 12 identical faces in the shape of pentagons. The octahedral is based on an eight-sided polyhedral with triangular faces. Some balls are based on the icosahedral with 500 dimples. As a general rule, the more dimples a ball has the better it flies, provided those dimples are about 0.15 in (0.38 cm) in diameter.
The size and depth of the dimples also affect performance. Shallow dimples generate more spin on a golf ball than deep dimples, which increases lift and causes the ball to rise and stay in the air longer and roll less. Deep dimples generate less spin on a golf ball than shallow dimples, which decrease lift and causes the ball to stay on a low trajectory, with less air time and greater roll. Small dimples generally give the ball a lower trajectory and good control in the wind, where as large dimples give the ball a higher trajectory and longer flight time.
However, the “gutty” ball went out of use around 1915, when multi-layer balls were developed, first as wound balls consisting of a solid or liquid-filled core wound with a layer of rubber thread and a thin outer shell. This design allowed manufacturers to fine-tune the length, spin and “feel” characteristics of balls. Wound balls were especially valued for their soft feel, and continued to be popular until the early years of the 21st century.
Today, golf balls are made of multiple layers. The core of golf balls are made of Surlyn©, a commercial thermoplastic polymer derived from petroleum. A two-piece ball consists of a solid rubber core with a durable thermoplastic (ionomer resin) cover. The three-piece ball consists of a smaller solid rubber or liquid-filled center with rubber thread wound around it under tension, and an ionomer rubber cover.
During the 1970s the interior of the ball improved further, thanks to a material called polybutadiene, a petroleum-based polymer. Though this material produced more bounce it was also too soft. The addition of zinc strengthened the material. This reinforced polybutadiene soon became widely used by the rest of the manufacturers.
By: Nalini Nadkarni
Faculty: University of Utah Biology Department
N. Nadkarni, Between Earth and Sky: Our Intimate Connections with Trees. (2008) Univ. of California Press, Berkeley, CA.]