A bowling ball is a spherical ball made from plastic, reactive resin, urethane or a combination of these materials which is used in the sport of bowling. Ten-pin bowling balls generally have a set of three holes drilled in them, one each for the ring and middle finger, and one for the thumb; however, rules allow for up to five finger holes. They generally range from six pounds to 16 pounds in weight. The maximum limit allowed in tournaments or league games is 16 pounds, but balls of up to 20 pounds are available. A five-pin bowling ball has no finger holes and is smaller so that the bowler can hold the ball in the palm of his or her hand. Candlepin bowling balls also fit in the hand, but are slightly smaller and lighter than five-pin balls. Most bowling alleys provide free balls for patrons to use, called "house balls", although bowlers may purchase their own. These are often customized, and can feature specially sized finger holes (in the case of ten-pin balls) or monograms. Because purchased balls are usually drilled to match the owner's fingers, most can throw a customized bowling ball that is one to two pounds heavier than the house ball they previously used.
Bowling balls come in many varieties of colors, and are often either a single flat color, a swirl-like design of multiple colors, gray or a single color with an iridescent look. It is even possible to obtain transparent bowling balls, some are even made white the clear polyester or plastic shell with a small object inside of them for a distinctive look. These objects look to be rather large but are in fact a lot smaller outside of the ball. Some objects have included skulls, footballs, and small bowling pins.
Inside the ball is a core which is dynamically imbalanced to cause the ball to try to stabilize as it is rolling down the lane. This makes the ball roll over a different point on the surface every time it revolves and "flares" or causes multiple rings of oil as it travels down the lane. Bowling ball cores are constructed with different densities as well. Some are center heavy (low rg) and some cores are made with the weight distributed more towards the cover of the ball (high rg). Low rg balls will spin more easily than the high rg balls.
Ten-pin balls 
USBC and FIQ regulation ten-pin bowling balls must weigh no more than 16 pounds (7.3 kg) (governing bodies do not regulate how light a bowling ball may be), have absolutely no metallic component materials used anywhere in their makeup, and have a maximum circumference of 27 inches (69 cm) directly in the equipment rules for tenpin bowling, which results in a maximum diameter of 8.59 inches (21.8 cm). The lightest ball generally available is the 6-pound (2.7 kg) weight, which is generally used by children. Ball weights between 12 and 16 pounds (5.4 and 7.3 kg) are common in adult league play. Since the physical dimensions of regulation balls remain the same, while the weight may differ, lighter balls are much less dense than heavier ones. Thus, balls under about 11 pounds will float when placed in water.
The behavior of a rolling ball on a surface is controlled by several factors, the most obvious being the bowler's delivery. In the delivery, the bowler can use or fight (intentionally or unintentionally) the force of gravity. After the ball is on the surface of the lane, friction, gyroscopic inertia, and gravity all become factors. These environmental influences can be segregated as either lane conditions or ball characteristics. Additionally, a bowling ball is not an absolutely uniform sphere—the gripping holes (and sometimes a balance hole) alone make that impossible.
Throughout the history of the USBC, bowling ball materials have evolved from wood, to rubber, to plastic, to urethane, to reactive urethane, to particle, and finally epoxy. Wood balls are now just museum pieces. Rubber balls are almost as hard to find; however, they may be found offered to casual bowlers at bowling centers, from their racks for those who do not own their own ball. Bowling balls have been constructed with a core made of one material, a spherical coverstock ("cover" or "shell"), and sometimes a "pancake" weight block of denser material intended to compensate for the gripping holes.
One of the most contentious issues that has arisen is whether significant restrictions should be imposed on bowling ball technology. Other considerations have been noted with regards to the weight of the bowling pins, lane oiling techniques, and with the construction materials and techniques used to build bowling lanes.
Grips and finger holes 
The way the finger holes are arranged on the ball surface changes the core dynamics; this will change how the bowling ball hooks down the lane.
There are three different basic types of bowling grips for bowling balls: conventional, semi-finger tip and finger tip; all other grips of any name (i.e., Sarge-Easter grip, etc.) are derivatives. In a conventional grip, the bowler's ring and middle fingers are placed into the ball up to the second joint, while in a finger tip grip the ring and middle finger holes are made to accept the bowler's fingers only up to the first joint. Beginner bowlers will start with the conventional grip, as it allows for the bowler the maximum grip on the bowling ball without feeling like he's going to drop the ball. Chris Warren was one of the few professionals that used the conventional grip.
Semi-finger tip has the bowler placing his fingers between the first and second joints. This grip is of choice for bowlers who want a clean release of the fingers, but also want maximum control. It also generates less hook, as strokers preferred this type of grip. Bowlers in the past, such as Dick Weber, used this grip. Brian Voss was one of several more modern-day professionals who used the semi-finger tip grip.
A finger tip grip requires more strength, but allows the bowler to release the ball with more lift, and a cleaner release, giving him more control in how the ball rotates after it is released. Most professional bowlers that throw a hook ball use this grip. Don Genalo, a former professional bowler, used the finger tip grip, but would also place his pointer and little fingers very close together with the other two, allowing his hand to stay behind the ball, while allowing his unusually long fingers to maximize the lift upon delivery.
For the players with extremely high rates of revolution ("rev rates") and skill level, a Sarge-Easter grip may be an option. This is when the middle finger is drilled to finger tip depth, while the ring is drilled to the conventional depth. It allows players with high revs to change their axis tilt and allow more forward roll as to keep the ball from over hooking. This is done to help achieve the forward roll without having to change or adapt ones game for this ball roll.
USBC regulations also allow for up to five holes to be drilled on a bowling ball—with the idea that a bowler can use all five digits to grip the ball. Some bowlers use only the middle and ring fingers, while leaving out the thumb, such as in the case of Jason Belmonte who uses the two-handed method. To cut down the hook for spares, some bowlers eliminate the ring finger, and grip the ball with just the middle finger and thumb, causing the release to have less lift; professional bowlers Gary Dickinson and Walter Ray Williams, Jr. perfected this technique.
The history of the bowling ball 
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Bowling can be traced back to approximately 5200 B.C., when ancient Egyptians used stones for their balls. Pre-Columbian Indians also practiced bowling variants.
The first bowling balls used in the United States were made of wood, especially oak, and lignum vitae wood. In about 1906 the first hard rubber balls were produced, such as the Brunswick "Mineralite" ball, and these remained the standard until the 1960s and 70s. These decades saw the emergence of plastic (polyester) balls.
In the early 1970s, people began experimenting with the hardness of the plastic balls. The reason for this is to allow the ball to "grab" the lane better. Plastic balls were difficult to hook on tough oil conditions. Until the 1970s, there were no rules regarding the hardness of the bowling ball's surface. PBA member Don McCune took advantage of the non-existence of such a rule. McCune at the time worked for Chuck Hamilton, who invented the "soaker"—a plastic (usually polyester) ball he softened "in the garage" with chemical solvents such as MEK, which would excrete a sticky substance, allowing the ball to hook more on oily conditions. At times, the balls were soaked to the point that the balls might even end up lopsided. Columbia—a more established manufacturer of bowling balls—came out with a series of "yellow dot" balls that were similar in function to the "soaker". The hardness of the ball's surface came under ABC scrutiny because of the increased scoring, particularly by McCune, who with his "soaker" won six PBA tournaments in 1973 and PBA Player of the Year honors. The ABC established a durometer hardness rule of 72, which barred even some of the out-of-the-factory softer balls. The PBA took the issue even further by applying a more strict 75 hardness rule. To effectively test the hardness, the PBA required each ball to bear a 0.25-inch deep hole, just above the finger holes. The durometer would be inserted into the hole, allowing the meter to perform the test beneath the ball's surface.
Sanding of the bowling ball surface was another technique to soften the ball's surface. Once the track area is located on the ball, the bowler would sand the track area to make the surface more abrasive, allowing the ball to hook more. And, bowlers would apply solvents to the ball's surface during tournament play—rubbing the chemicals into the cover using a rag. More rules by the ABC had to be passed, including restrictions from doctoring the bowling ball's surface at any time once the ball has passed inspection by an official.
At some point in ball making and drilling, the ABC introduced ball balance regulations to prevent people from taking advantage of certain forms of "weighting". It was possible to drill the grip at a location relative to the weight block so that it would achieve some effect, such as to help the bowler make it roll earlier or hook more. Guide holes were also used to stabilize the roll of the ball, by drilling the guide hole in perpendicular to the track area of the ball. This allowed the ball to avoid over-hooking or roll-out before hitting the pocket.
In 1981 Ebonite began manufacturing the very first urethane cover stock bowling balls and sold the rights to AMF. Ebonite produced AMF balls at that time. Ebonite did not believe that bowlers would pay the $80.00 price this new technology would demand. That ball became the AMF Angle and this one coverstock change allowed the ball to get a better grip on the urethane finishes used on natural wood lane surfaces, which changed the nature of the bowling game significantly. Then in 1993, Nu-Line Industries produced the X-Calibur, a reactive resin cover. Part-time professional Steve Cooper was the owner and president of the corporation. But production lagged in the early days, allowing firms like Storm, Brunswick and Columbia to enter the reactive market by the following summer. The race to create more and more dynamic balls was on.
Prior to about 1990, the ABC "static" ball balance regulations were adequate. The core was usually a uniform sphere centered inside the ball. Then competition among ball manufacturers motivated the production of balls designed to offer more than the "static balance" tricks. Materials and fabrication changes have since allowed the assembly of balls whose interior components have a much greater range of density, thereby offering a new ball choice that, in physics terms, involves the moment of inertia of a solid sphere. Eventually, "dynamic balance" regulations had to be adopted.
Currently there are 4 different types of coverstocks for ten-pin bowling balls: polyester, urethane, reactive resin and particle resin. Each coverstock of a bowling has its own intended friction and purpose when it is rolled down the lane. The coverstock also allows the bowling ball to display its potential.
Polyester or plastic bowling balls have the lowest friction and is meant to be rolled down the lane in a straight path. There are no pores in the ball, it will not absorb any oil as it rolls down the lane and will simply slide down. This type of coverstock is generally used by professional and competitive bowlers for converting spares.
Urethane bowling balls provide slightly more friction than polyester bowling balls. Just like polyester bowling balls, urethane bowling balls have no pores in the ball. This type of ball is also generally used like a polyester ball but will have a better reaction as it rolls down the lane.
Reactive resin bowling balls are more common among professional and competitive bowlers. This coverstock is a similar coverstock to the urethane but also has pores. The pores in the bowling ball will allow the ball to absorb the oil as it is rolling down the lane. This will allow the ball to retain the energy from the release and have a stronger reaction when it comes in contact with a part of the lane without oil (usually towards the end of the lane or "backend")www.youtube.com/watch?v=2ZY59BvV4qc Particle resin bowling balls are also common among professional competitive bowlers. This coverstock incorporates silica particles into reactive resin coverstock, which allows the ball to slide down the lane more than the reactive resin bowling balls. It is easier for the bowler to control the reaction of this bowling ball than that of the reactive resin bowling ball.
In order to continue this discussion, a systematic description of ball rotation must be introduced. For various formulaic purposes, physicists divide rotation into three components, assigning portions to x, y and z axis that are mutually perpendicular. For bowling, the x-axis can be assigned to a line that is parallel to the foul line, the y-axis to the line parallel to the boards, and the z-axis to the vertical. Forward-roll is rotation about the x-axis, side-roll is rotation about the y-axis and mid-roll (or spin) is rotation about the z-axis. The pure full-roller delivery is a combination of forward- and side-roll only. Semi-rollers include spin. Spinners may have very little side roll. In a very strict physics sense, a ball may be delivered with rotation, but usually not in a roll, because that would imply complete traction. The technique of the great majority of bowlers involves a delivery that starts the ball in a skid that evolves into a roll that hooks into the pins.
It has been known since before the 1960s that a "full-roller" type of delivery does not hook as well as "3/4 rollers" on oily lanes. On successive rotations, the "full roller" repeatedly contacts the lane on the same full circumferential circle, on which the oil accumulates, making it harder for the side-roll to find traction and create hooking action. The "full-roller" had been the dominant choice before the changes in lane coatings and oil. The "semi-roller" is now preferred (it may also be called "3/4 roller" or by other slang terms). With a 3/4-roller a bowler puts the ball into a rotation whose contact ring is smaller, and on successive rotations enlarges (subsequent examination of the ball often shows a flaring of the circles of oil). This is because at every spot along the circle, friction reduces the rotation, and that includes the spin component, causing rotation on a continually larger circle. This has the effect of bringing relatively dry ball surface in contact with the lane, increasing traction for both forward-roll and side-roll. It probably goes without saying why bowlers often wipe oil off the ball.
Another effect of ball imbalance (either static or dynamic) is the ability to introduce gyroscopic effects on the rotation. The component of imbalance along the rotation axis provides a leverage that can change the orientation of the axis on its horizontal plane, an action physicists call precession. It is basically the same thing as a spinning toy top "going around in a circle." In the case of a rotating bowling ball, as it moves along the lane, there is only time for its total rotation axis to move along a short arc, but this is enough to reorient the total rotation so that some of the forward-roll becomes side-roll, increasing the side-roll provided in the bowler's delivery, thereby achieving more hook. It is possible to use dynamic ball balancing to achieve a stronger gyroscopic effect than static balancing alone.
The advent of dynamic ball balancing meant that bowlers could achieve "ball flare" without the need for a 3/4 roller delivery, and more hook. Additionally, balls with covers that create higher friction, such as "particle" balls, provide for more traction and hook. Bowlers are embracing these choices, buying balls whose characteristics complement or enhance their deliveries.
It is the opinion of many people in the bowling community that these advances in bowling ball technology have undermined bowling skill and have made it more difficult for lane maintenance personnel to lay out fair and credible conditions for participants. This is because advanced players using hi-tech balls "need" more oil to score high and might complain about the radical behavior of their balls on "dry" lanes. At the same time, less aggressive players might complain when they can not get their balls to hook. These complaints have been part of the game throughout USBC history. It has been a matter of which group prevails within the USBC—or what new technology comes along next.
Manufacturers of ten-pin bowling balls 
- Tech-Line Products
- Motiv Bowling
- Ebonite International, which includes
- Columbia 300 Industries
- Ebonite Bowling
- Hammer Bowling
- Track International
- Dyno-Thane (Overseas brand only)
- Brunswick Corporation
- Quantum (contract made by Brunswick overseas)
- MoRich Enterprises (contract made by Brunswick)
- Visionary Bowling Products
- Storm Bowling
- Seismic Bowling
- 900 Global
- Lane #1 (contract made by 900 Global)
- Elite (contract made by 900 Global)
- Radical Bowling (contract made by 900 Global)
- Pyramid Bowling
- Lord Field
- Gem Tech
- Jet Bowling
- Lane Masters/Legends
Displaying bowling balls 
Bowling balls are often displayed in homes and businesses. Clear bowling balls and balls with images and graphics printed on them are often used to advertise companies, cartoon characters, sports leagues and professional bowlers. Since a bowling ball is round and therefore is not stable on a flat surface like a desk or shelf a bowling ball cup is necessary to keep the ball stationary and facing the desired direction. A ball cup can also be used as a utility item. to keep an extra ball stationary while one is bowling.
Candlepin bowling balls 
The maximum regulation candlepin ball diameter is 4 inches (11 cm), with a maximum weight of 2 pounds 7 ounces (1.1 kg), and with the regulated weight of a single candlepin being slightly heavier at 2 pounds 8 ounces (1.1 kg) the candlepin sport could be said to pose a greater challenge to the player—due to the almost non-existent difference of the weight between the ball and one candlepin—than any of the other forms of bowling that use ten pins in them, even when it is considered that up to three balls are used in a frame of candlepins, with fallen pins allowed to remain on the lane after the first ball delivery in a frame. 1⁄2
Duckpin bowling balls 
Duckpin balls weigh 2–4 pounds (0.91–1.8 kilograms) each. The duckpin ball has a maximum diameter of 5 inches (13 cm), slightly larger than a candlepin ball but, like a candlepin ball, contains no finger holes. Duckpins are correspondingly shorter and lighter than their ten-pin equivalents and it is more difficult to knock them all down with a single roll.
Five-pin bowling balls 
Five-pin bowling balls have no finger holes and are between 4.75 to 5 inches (12.1 to 13 centimetres) in diameter. They weigh between 3.50 and 3.625 pounds (1.59 and 1.644 kilograms). The smaller size and lighter weight of the balls allows bowlers to hold the ball in the palm of their hand when bowling.
- Core / Cover Stock Descriptions at bowlingball.com
- Bowling Ball Dynamics
- Ball Dynamics and Hook Potential at bowlingball.com
- Tips on the Grip at bowlingball.com
- Learn About Bowling Balls
- Solving the Mysteries of the Two-handed Approach Delivery
- Walter Ray Replies to Questions
- Display Your Favorite Bowling Balls with a Bowling Ball Cup