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How Are Bowling Balls Made?

About 100 million people chuck bowling balls down bowling lanes each year around the world, the average ball clocking about 20 miles per hour before they hit the pins. Bowling balls are without a doubt, a crucial aspect of bowling, but is often overlooked because of its deceiving simplicity. From the normal person's perspective, the bowling ball is simple a hard, spherical object used to knock down some pins, and while partly true, there's way more to the plot than the just the solid spheres that they are.

From the early crude stone balls of Ancient Egypt to the modern reactive urethane balls. bowling balls are the product of years of trial and error, the changing rules of the game, and advancements to material science. But, how exactly are bowling balls made? We'll look into that right now!

What Were Bowling Balls Made Of?

The first ever discovered man-made bowling balls were made of a porphyry stone, which is an igneous rock that has large grains of crystals. These porphyry stone balls were found in an Egyptian child's grave in 1895, which went all the way back to the Egyptian protodynastic period in 3200 BC.

Excavated balls in other areas revealed that husk of grains was once used as materials for bowling balls. which were covered in leather and bound together with string. Porcelain was also another popular material which early bowling balls were made from.

Prior to 1905, bowling balls were predominantly made from lignum vitae which is a type of hardwood. Exported primarily from the Caribbean, lignum vitae is one of, if not the densest wood traded, and offered early bowlers a reliable, hard, and durable bowling ball. But lignum vitae balls were quickly ditched when rubber balls were introduced.

There were two primary companies who were credited with the earliest rubber bowling balls which were Ebonite and Brunswick; Ebonite with their rubber bowling ball, and Brunswick with their "Mineralite" bowling ball, which was a type of vulcanised rubber. Rubber balls were known for their grip, but had to be towel cleaned every few throws to maintain.

During the late 1950's, polyester or plastic bowling balls were introduced. A bowling ball and pin manufacturing company called Columbia Industries were the first to create a plastic bowling ball, specifically a polyester resin ball. Plastic bowling balls become the new normal, rendering the previous rubber bowling balls obsolete.

In the early 1980's, bowling balls again had a large makeover, this time with the introduction of urethane bowling balls. Although not exactly certain, it is collectively agreed that the famous AMF company created the first urethane bowling ball called the 'AMF Angle Ball'. These new bowling balls possessed greater friction in the new recently added polyurethane lane finishes to most bowling centres that time.

Almost all bowling balls today were the product of the early 1990's. This time saw the development of 'reactive' bowling balls or reactive resin balls, which were created by adding other 'things' to the urethane surface materials of the ball which created tiny oil-absorbing pores. This enhanced the traction of the balls. The late 1990's saw the development of 'particle enhanced' bowling ball. These balls had tiny particles added in the reactive surface of the balls to provide even greater traction. What is added to the surfaces exactly? Like the recipe for Coke Cola, that is a secret only the companies know.

Accepted Specifications Of A Bowling Ball

The United States Bowling Congress (USBC) and the International Bowling Federation (or World Bowling (WB) ) have defined a set of universal specifications and guidelines for bowling balls, specifically for competitive play.

Some of the USBC guidelines include:

  1. The weight of a ball must be less than or equal to 16 pounds, or 7.3 kilograms.

  2. The diameter of the ball must be 8.5 inches, or 21.59 centimetres - 8.595 inches, or 21.83 centimetres

  3. A Hardness value of 72

  4. A maximum Mohs' hardness of 6

These guidelines even include things such as radius of gyration, coefficient of restitution, centre of gravity marking locations and drilling specifications.

For the full list of specifications, please click here (page 3 - page 14)

How Exactly Are They Made?

A 10-pin bowling ball is made by 4 basic steps - the creation of the central core, forming of the shell, applying of the coating, and then the finishing. The cross-section of a bowling ball looks somewhat like a planet, which is an awesome way of remembering how they're made.

Creation Of Central The Core:

This is 1st step of the production process. Dozens of different core shapes exist for different bowling ball models such as the lightbulb core, spherical core, elliptical core, oblong core or the combination core. However, the process is still the same.

1) A resin mixture is poured the core mold and then is left to set.

2) Once set and dried, the cores are removed from the moulds.

3) The core is then drilled to make a pinhole.

Forming Of The Shell

4) The core is then placed into the second spherical mold, sometimes called the coverstock mold. Workers make sure that the core is attached to the pin so that it is perfectly straight. This ensures even distribution of the shell.

5) The core is pressed down using an industrial press, and the top of the mold is locked into place.

6) A special liquid polymer blend is poured into the mold, with a special ingredient which causes the material to solidify slowly. The thickness of the shell depends on the type of ball being made.

7) After a few days, the shell has set, and is cut in a rough spherical shape.

Applying The Coating

8) The now core+shell is placed into the third mold. A reference tool is used to align the core+shell, and is pressed into a pin.

9) Now the coating, sometimes called the veneer, is poured into the mold. The coating is scientifically formulated to increase traction called polyurethane, and is usually made with a combination of urethane, plasticizer, colourant and a chemical called ISO.

10) A chemical reaction will cause the coating to heat up, which results in the near instant solidification. The near-completed bowling is then placed into an oven to boost the chemical reaction.

11) A spinning grinder is used to shave off any protruding pieces made from the mold stage.


12) A lift system delivers the bowling ball to a complex industrial sanding machine. The grit of the sandpaper varies, depending on the performance desired by the bowling ball.

13) A heat machine is used to heat stamp trademark information on the bowling.

14) A final sanding machine is used with a constant flow of water. This is done to remove any powdery residue. The smoother the ball, the less of its ability to curve, so this step still closely monitored.

15) The surface is then polished for the last time, and drill holes may be implemented. If so, reference tools are strictly used to drill the finger holes.

The entire manufacturing duration for one ball is around 2-5 hours.

Do Bowling Balls Go Bad?

Bowling balls, like anything, will break down with continued use. The rate at which it breaks down is influenced by a variety of factors, such as how much you're playing, how you take care of the ball, the type of ball, and quality of the ball. But for the average bowling ball, with average maintenance, should not go bad until 5-10 years.

Modern bowling balls have shells which are soft and porous compared to early balls and is done primarily to protect the lanes, and general performance. This obviously means that the balls are prone to damage especially from large amounts of force. If you find that the bowling ball has cracks, this is usually a death sentence, as the likelihood of the ball straight up splitting and revealing the core is quite high. This is why I recommend you to replace any balls which have large cracks.

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