What Is A Baseball Made Of?

It’s fun to watch a game of baseball. Hotdogs, Cracker Jacks, and the chance of catching a dinger in the stands make it an exciting experience. Many fans, lucky enough to catch a baseball in their leathers, won’t know what materials are inside the souvenir. What is a baseball made of? Baseballs are made of….

A baseball is made out of cork and two rubber layers that form a ball known as the pill. Four layers of wool and polyester yarn are spun around the pill to form the center. The center is covered with two eight-shaped leather pieces before being stitched up with red cotton thread.

Baseballs are the most important element of the sport we love. The iconic baseball’s general composition rules and regulations have been the same since the late 50s. The cork found inside an MLB baseball has been used for more than a century. A baseball is like an intricately layered cake; it needs all the elements to come together before being unleashed onto bats across the country.

baseball pill

What Is A Baseball Made Of?

Ever wondered what a baseball is made out of? One element of a baseball’s construction is the instantly recognizable white leather. A baseball construction involves more than cowhide and red stitching. If you have one lying around, do a simple experiment and cut it in half.  

You will find that a baseball is made out of the following materials:

  • Cork 
  • Rubber
  • Wool and polyester yarn
  • Rubber cement adhesive
  • Cowhide
  • Red cotton thread

Rawlings is the company that produces millions of baseballs for the MLB each season, and they are contracted to manufacture baseballs that comply with specific league standards. 

MLB has the following official rule, Rule 3.01, in place regarding the construction of a baseball:

“The ball shall be a sphere formed by yarn wound around a small core of cork, rubber or similar material, covered with two strips of white horsehide or cowhide, tightly stitched together. It shall weigh not less than five nor more than 5¼ ounces avoirdupois and measure not less than nine nor more than 9¼ inches in circumference.”

Each ball manufactured by Rawlings must be uniform in circumference and weight to ensure that the game is played on an equal footing. For those fans wondering what ball in world sport comes close to a baseball’s construction, look no further than the red, white, and sometimes pink and orange cricket ball.

Baseballs Are Made Out Of Cork And Rubber Called A Pill

The first material used when constructing a baseball is a sphere cork ball covered with two layers of rubber to form the core. The core is smaller than a golf ball, measuring slightly over 4 inches in circumference, with a half-ounce weight.

A baseball’s core must be manufactured to exact manufacturing standards regarding diameter, overall weight, and material composition. After manufacturing the perfect core (also known as the pill), it’s covered by a latex adhesive.

To ensure that the pills are completely covered with latex adhesive, the pills are thrown into a drum. Rollers spin the drum resulting in perfectly coated cores that retains a level of stickiness when removed from the drum.

When the pills are removed from the spinning drums, it’s time to take out the yarn. 

rawlings baseball

Baseballs Are Made Out Of Wool and Polyester Yarn

The next step in constructing a baseball involves wool yarn and a unique pill-spinning machine. The special machine fits a pill and spins it around so that a layer of yarn is spun around it. The initial layer consists of four-ply blueish-grey wool yarn.

The second layer consists of three-ply white wool yarn. The following layer is a three-ply blueish-grey wool yarn, finished with a polyester and cotton blend white yarn. 

After spinning the four layers of yarn onto the pill, it should increase the spherical size to plus-minus 9 inches in diameter. The yarn-spun pill is now referred to as a center.

The spun wool yarns give the baseball the durability and flexibility to spring back into shape after batters hit the sweet spot.

Baseballs Are Made Out Of Rubber Cement Adhesive

When the four layers of yarn are spun around the pill, and the spherical shape is approved in size and shape, the yarn ball is coated with a type of rubber cement adhesive. 

The coating is done by adding the rubber cement adhesive to a spinning drum and then adding the centers to allow the adhesive to bond with the yarn. The centers are then left to dry for 2 days, which will retain a stickiness, making it easier for the leather to adhere to the center.

baseballs made out of

Baseballs Are Made Out Of Cowhide Leather And Red Cotton Thread

The final part of constructing a baseball is adding the material that most of us love and adore, the iconic white leather (Rawlings uses cowhide that’s colored white). A hydraulic press punches out figure eight leather shapes. The figure eight leather shapes are manufactured with stitching holes around the edges.

The date and lot number are stamped on each figure eight leather cut-out before adding a water-based adhesive to one side of the cut-out. The water-based adhesive ensures that the center and leather adhere to each other effectively.

Two figure-eight cut-outs are used per ball and fit perfectly around the sticky center. The balls are then clamped before skilled sewers start to work their magic. The sewers, who expertly operate two needles, bring all the elements together by pulling the red thread through the center and the pre-punched stitching holes.

Cross-stitching done to perfection is what you get to observe when holding a baseball in your hand. The sewer will use wax on the threads to ensure that the threads don’t slacken and tangle while the stitching masterclass is underway.

The red cotton thread used comfortably results in 108 double stitches (216 in total), with the first and last being hidden from view.


The process of manufacturing an MLB-approved baseball involves specialized machinery and skilled sewers. Who would have thought that a product consisting of cork, rubber, yarn, adhesive, cowhide, and red cotton thread could bring so much joy to so many people? 

Take me out to the ball game!

Matt Crouch
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