From a baseball historian, here is an overview of how the construction of baseballs has evolved over the years and how a baseball is made today.
The earliest baseballs were made in the mid-19th century and had a relatively simple construction compared to modern ones. They consisted of a core made of cork or rubber, wrapped with yarn or string, and covered with leather. The stitching on these early baseballs was usually done by hand, creating a visible and prominent seam.
Over time, advancements in materials and manufacturing processes led to changes in the construction of baseballs. In the early 20th century, the cork and rubber core was replaced by a solid rubber core, which provided a more consistent and lively bounce. The use of yarn or string continued, but the covering material evolved to a more tightly stitched horsehide leather (there was some cowhide used too), offering better durability and performance.
In the mid-1970s, significant changes were made to the baseball's construction. The traditional horsehide cover was replaced with cowhide, which was more readily available and less expensive. This change resulted in slightly different playing characteristics, as cowhide had a smoother texture than horsehide.
Today, the process of making a baseball involves several steps. The core is typically made of rubber and consists of layers of cork and/or rubber wrapped tightly together. The core is then surrounded by multiple layers of wool yarn, which helps provide shape, density, and resilience to the ball.
The yarn-wrapped core is then covered with two pieces of cowhide leather, which are cut into a figure-eight shape. These pieces are machine-stitched together using 108 stitches, forming the characteristic raised seams that allow pitchers to grip the ball better and generate movement when thrown.
To enhance the ball's durability and performance, the leather covering is often treated with various substances like water-resistant coatings or special finishes. These treatments can affect the ball's grip, feel, and flight characteristics to some extent.
In professional baseball, baseball manufacturers, such as Rawlings, produce the official game balls under strict specifications set by the league. The balls undergo quality control checks to ensure consistency in weight, size, and performance.
It's worth noting that there have been occasional adjustments to the construction of baseballs throughout history, including changes to the materials, stitching patterns, and even alterations in the ball's size and weight. These changes often reflect efforts to balance the game's offensive and defensive aspects or address other factors impacting the game.
Overall, the evolution of baseball construction has been driven by a desire to improve the ball's consistency, durability, and performance while maintaining the traditional look and feel that players and fans have come to expect.