What are Bowling Balls Made Of? [Inside a Bowling Ball]

When people think about what are bowling balls made of, they often think it is a solid construction. However, most bowling balls are made two pieces. The main difference is that sometimes the core is shaped differently and this will make a difference in your throwing attempts. Here’s a closer look at what goes on inside a bowling ball.

Bowling Ball History

Before everything though, you’ll need to know more about the past of the bowling ball. Bowling is actually a pretty old sport. There are many games all over the world that had people rolling balls across an area trying to strike pins.

However, in these primitive games, the ball was often smaller and smoother. A good example of these balls are the balls used in the French game of pétanque. These are small steel balls that fit completely inside a person’s hand.

With the dawn of the 20th century though, standardization became the common concern for many bowling enthusiasts. This is when the more modern and larger bowling balls came into existence. The earliest official balls were made from wood, specifically that of lignum vitae. However, that quickly got phased out when rubber was discovered. The lighter and bouncer material allowed for a much more enjoyable game. This in turn got replaced in the 50s by the more modern polyester.

The Modern Bowling Ball

Today’s bowling ball has changed a lot since then, too. The last bowling ball material revolution came in the 1980s and has continued on to this day. The main change is another shift to polyurethane from polyester.

This was mainly done because of how polyurethane interacts with the surface of the bowling lane. Polyurethane coverstocks create a lot more friction when they move. The result is that bowling balls tend to curve more when they are used. A lot of people were surprised at how they performed so well when it comes to hooking and striking pins more accurately.

Additionally, manufacturers were experimenting with different kinds of bowling ball cores. The cores are the heart of bowling ball and the innovations that they made to the core made it possible for even more different spins on each throw.

The latest developments came about in the 90s. These came in the form of reactive resin and particle coverstock. They used to be both equally popular but in the end reactive resin won out. Particle coverstock was designed to have microscopic particles on the surface of the ball. The result was greater friction and the inevitable increased hooking as the ball gripped tight to the lane surface.

Reactive resin is pretty similar in idea. However, the higher friction came from the fact that the resin was an advanced form of polyurethane. It just raised the porosity level of the coverstock to give it a better grip on the lane.

Specifications

When the American Bowling Congress was founded in the 1890s, it set forth the standard regulations for making a bowling ball. They pretty much set forth the rules that determine the legality of the ball. The main thing that they require is that a ball only has to have a diameter between 8.5 and 8.595 inches, while not weighing more than 16 pounds.

Making a Bowling Ball

Knowing how are bowling balls made can tell you how effective your ball is going to be on the lane. There are a couple of steps that go into making your bowling ball. The very first step is to make the core.

When people think of what is inside a bowling ball, they imagine just another version of the bowling ball. Most of the time, this is the truth. Most basic ball just have core shaped like a sphere.

However, some manufacturers like to put a spin on this. Some cores are light bulb-shaped, while other are elliptical, and some are even a combination of both. The focus of the weight of the core will influence how it spins when the bowler throws it.

As for bowling ball core material, some people think that bowling balls are made of metal to be so heavy and solid. The truth is, nowadays, people actually mix dense materials like bismuth or graphite to resin to create modern cores. The result is a heavy plastic or ceramic product that usually had to be fired in a kiln.

In the past, bowling balls did not have any cores. They actually had a weighted block on one end and they were filled with filler material. Some balls still have a counterweight to make the spin more balanced. This is usually a few ounces of iron oxide or zirconium.

After the core is finished, the next step is to put it inside the coverstock mold. The core is usually pinned in place to keep it in the right position as the coverstock material is poured into the mold.

There are three plastics that makeup the basic coverstock. The least expensive is the traditional polyester. This is what you’d get if you don’t want to hook as much. The next step up is the polyurethane coverstock. These allow you to hook more and give you a nice curve in the lane. Finally, reactive resins are the top of the heap. They’re the most expensive and are treasured for providing the most hook.

​After the coverstock is put in, the pin that originally held the core is taken out and replaced with a plastic dowel. This is usually used as a reference point from when the holes are drilled into the ball for the final touches.

​The final step is to cut down the bowling ball to specifications. This usually done with a lathe and the makes shave off the excess coverstock depending on the specifications. Another option is to use a centerless grinder that does the same thing automatically.

​When the size requirements are met, the manufacturer then starts to sand down the exterior until a matte finish or a polish is achieved. With that done, the ball is then ready to be shipped to customers.

Photo Credit: ShutterStock, MadeHow