Billiard ball

A billiard ball is a small, hard ball used in cue sports, such as carom billiards, pool, and snooker. The number, type, diameter, color, and pattern of the balls differ depending upon the specific game being played. Various particular ball properties such as hardness, friction coefficient, and resilience are important to accuracy.

History

Early balls were made of various materials, including wood and clay. Although affordable ox-bone balls were in common use in Europe, elephant ivory was favored since at least 1627 until the early 20th century; the earliest known written reference to ivory billiard balls is in the 1588 inventory of Thomas Howard, 4th Duke of Norfolk. Dyed and numbered balls appeared around the early 1770s. By the mid-19th century, elephants were being slaughtered for their ivory at an alarming rate, just to keep up with the demand for high-end billiard balls – no more than eight balls could be made from a single elephant's tusks. The billiard industry realized that the supply of elephants was endangered, as well as dangerous to obtain. Inventors were challenged to come up with an alternative material that could be manufactured, with a US$10,000 prize being offered by a New York supplier.
Although not the first artificial substance to be used for the balls, John Wesley Hyatt patented an "ivory imitation" composite made of nitrocellulose, camphor, and ground cattle bone on May 4, 1869. The material was a success, and was sold as Bonzoline, Crystalate, Ivorylene until the 1960s, and was used by prominent professional players such as John Roberts Jr, Charles Dawson, and Walter Lindrum. The ivory substitute was one of the most significant early reinforced plastics; induced the global growth of billiards, pool, and snooker; and helped create a modern idea that the artificial can surpass the natural. It is unclear if the cash prize was ever awarded, and there is no evidence suggesting he did in fact win it.
However, Hyatt's composite had problems. One of the most relevant is cellulose nitrate flammability, not because of making the billiard balls explode, as is often claimed, but because of the dangers of handling it in its pure form during manufacturing. Another problem was related to camphor mass exploitation, leading to the devastation of Taiwan's forests and displacement of indigenous communities. Subsequently, the industry experimented with various other synthetic materials for billiard balls such as Bakelite, acrylic, and other plastic compounds.
The exacting requirements of the billiard ball are met today with balls cast from plastic materials that are strongly resistant to cracking and chipping. Currently Saluc, under the brand name Aramith and other private labels, manufactures phenolic resin balls. Other plastics and resins such as polyester and clear acrylic are also used.
Ivory balls remained in use in artistic billiards competition until the late 20th century.

Types

Carom billiards

In the realm of carom billiards games, three balls are used to play most games on pocketless billiards tables. Carom balls are not numbered, and are 61–61.5 mm in diameter, and a weight ranging between with a typical weight of. They are typically colored as follows:

White: for the first player
Yellow: cue ball for the second player
Red: the .
English billiards

uses the same number of balls as carom billiards, but the same size as snooker balls, as the game is played on the same size table as snooker. Each player uses a separate cue ball, with modern English billiards sets using one white ball with red spots and the other being yellow with red spots. The object ball used is red, but in some additions, it is red with white spots.

Pool

Pool balls are used to play various pool games, such as eight-ball, nine-ball, and straight pool. These balls, the most widely used throughout the world, are smaller than carom billiards balls, and larger than those for snooker. According to World Pool-Billiard Association equipment specifications, the weight may be from with a diameter of, plus or minus.
The balls are numbered and colored as in the table show here. Balls 1 through 7 are the of and 9 through 15 are the. The 8 ball is not considered part of either suit. Striped balls were introduced around 1889.
Rotation games do not distinguish between solids and stripes, but rather use the numbering on the balls to determine which must be pocketed. In other games such as straight pool neither type of marking is of any consequence.
Some balls used in televised pool games are colored differently in order to make them more distinguishable on television monitors. Most commonly, the dark purple used on the 4 and 12 balls is replaced by pink to make it easier to distinguish the 4 from the black 8 ball, and similarly the 7 and 15 balls use a lighter brown color instead of a deep maroon. Other, less common color substitutions are also found, dependent on manufacturer. These sets often have a cue ball with multiple spots on its surface so that placed on it is evident to viewers.
Baseball billiards uses 21 balls instead of 15, adding 6 extra striped balls, with the 16 ball being black and the 17 through 21 balls being the same colors as the 9 through 13 balls.
Coin-operated pool tables, such as those found at bowling alleys, arcades, or bars/pubs, may use a slightly different-sized cue ball, so that the cue ball can be separated from object balls by the table's ball return mechanism and delivered into its own ball return. Such different sized cue balls are considered less than ideal because they change the dynamics of the equipment. Other tables use a system where a magnet pulls a cue ball with a thin layer of metal embedded inside away from the object ball collection chamber and into the cue ball return, allowing the cue ball to more closely match the object balls in size and weight. More recently, optical systems that recognize the cue ball, which is more translucent than the other balls due to its solid white color, and separate it mechanically have been developed.

British-style eight-ball pool

In British-style eight-ball pool and its blackball variant, fifteen object balls are used, but fall into two unnumbered s, the and, with a white cue ball, and black 8 ball.
Aside from the 8, shots are not since there is no reliable way to identify particular balls to be pocketed. Because they are unnumbered, they are wholly unsuited to certain pool games, such as nine-ball, in which ball order is important. They are typically smaller than the American-style balls; the most common object ball diameters are and. The yellow-and-red sets are sometimes referred to as "casino sets" as they were developed to make identification of suits easier for spectators at eight-ball championships often held in casinos. Such sets were sold by the Brunswick–Balke–Collender Co. as early as 1908. Similar to standard pool balls, there are also special sets designed for televised games; these sets have a black-striped 8 ball, and a spotted cue ball.

Snooker

Ball sets for snooker consist of twenty-two balls in total, arranged as a rack of 15 unmarked red balls, six s placed at various predetermined spots on the table, and a white cue ball. The colour balls are sometimes numbered with their point values in the style of pool balls for the home market.
Snooker balls are standardized at in diameter within a tolerance of plus or minus. No standard weight is defined, but all balls in the set must be the same weight within a tolerance of. Snooker sets are also available with considerably smaller-than-regulation balls for play on smaller tables, and are sanctioned for use in some amateur leagues. Sets for American snooker are typically, with numbered colour balls.
The set of eight colours used for snooker balls are thought to be derived from croquet, which uses the same set of colors. Snooker was invented in 1884 by British Army officers stationed in India. Croquet reached its peak popularity at the same time, particularly among people in the same social context. There are many other similarities between croquet and snooker, which when taken together, suggest that the derivation of the latter owes much to the existence of the former.
Some snooker variations use extra balls:

Snooker plus - uses an orange ball with a value of 8 points and a purple ball with a value of 10 points.
Power Snooker - uses a white ball with red stripe which doubles all the ball values for 30 seconds.
Tenball - uses a yellow ball with black cross which values 10 points.
Riyadh Season snooker - uses a gold ball with a value of 20 points.
SnooPool - uses a violet ball, a gray ball and a gold ball. Since this game is a mix of Snooker and Pool, the balls have no points of values, while the gold ball replaces the black ball in grand finals.
Other games

Various other games have their own variants of billiard balls.
Russian pyramid uses a set of fifteen numbered white balls and a maroon, red or yellow cue ball that are even larger than carom billiards balls at. Kaisa has the same pocket and ball dimensions but uses only five balls: one yellow, two red and two white cue balls, one for each player.
Bumper pool requires four white and four red object balls, and two special balls, one red with a white circle and the other white with a red circle; all are usually in diameter. Bar billiards uses six or seven white balls and one red ball in diameter.

Novelty balls

There is a market for specialty cue balls and even entire ball sets, featuring sports team logos, cartoon characters, animal pelt patterns, or other non-standard decorations.
Entrepreneurial inventors also supply a variety of novelty billiard games with unique rules and balls, some with playing card markings, others with stars and stripes, and yet others in sets of more than thirty balls in several suits. Marbled-looking and glittery materials are also popular for home tables. There are even blacklight sets for playing in near-dark. There are also practical joke cue and 8 balls, with off-center weights in them that make their paths curve and wobble. Miniature sets in various sizes are also commonly available, primarily intended for undersized toy tables. Even an egg-shaped ball has been patented and marketed under such names as Bobble Ball and Tag Ball.