The process for making an all-leather NBA ball is both about science and feel.
Getting the all-leather NBA basketball into the hoop is the entire point of the game, so coming up with exacting standards for the ball itself is nothing short of a science for Chicago-based Wilson Sporting Goods. Hotmelt Coating Machine For Label
Crafting the NBA ball requires four layers of materials, each with its own defined processes that result in a final uniform product for distribution across the 30 teams in the NBA. Wilson, which served as the ball maker for the first 37 years of the NBA, has regained its status as the official provider of the NBA ball for the 2021–2022 season. Now in its second year of the contract, Popular Mechanics went behind the scenes of the NBA ball-making process.
Before production of the ball could start, Wilson met with NBA players and equipment managers to learn the nuances of their performance needs. “They want that consistent feel, whether in Miami or the middle of February in Minnesota,” Kevin Krysiak, senior director of research and development at Wilson, tells Popular Mechanics. “They want the ball to feel the same.”
Every team receives an allotment of new balls each year, though most purchase more for practice facilities. Krysiak and Skip Horween, president of Horween Leather, both say that the NBA being the only league to use a genuine leather ball makes the production process more noteworthy.
Composed of a rubber mix balanced with a high percentage of butyl rubber and a low percentage of “lively” natural rubber, the bladder controls the ball’s air, which impacts rebound and shape. The butyl is known for quality air retention, allowing the ball to maintain its 8-psi standard while inflating it.
According to NBA specifications, when dropped from a height of 72 inches, the ball must rebound 52 to 56 inches. Players don’t want a ball to be too lively; They want to control the force. They also want consistency throughout the game.
To create the bladder, the rubber is placed in a vulcanization mold, which it sits inside for about eight minutes at temperatures between 150 to 160 degrees Celsius. Once molded, there’s nothing to stop the bladder from growing like a balloon when inflated, so Wilson puts between 3 and 4 psi of air in it for handling.
While air certainly accounts for the bulk of the space inside a ball, material from the bladder out is about 5 millimeters thick. The bladder accounts for about 0.8 to 1 millimeter of that.
Imagine thread continuously wrapping the bladder. That’s the winding layer. A mix of both nylon and polyester—a bit heavier on the nylon side to get the right amount of tensile strength for shape retention and rebound—the winding layer “is all about controlling the shape of the ball,” Krysiak says.
The machine Wilson uses rotates the bladder as the winding is applied, self-balancing to ensure the thread goes on evenly. A small adhesive bath gives it additional structure to keep things from falling apart.
Because the bladder starts perfectly spherical, it would quickly turn into an egg without the winding layer. “If you do the winding layer right,” Krysiak says, “it will keep the ball perfectly spherical.”
Another layer of rubber—this a completely different mix than the internal bladder—helps with rebound and structure, and also serves as a canvas for the ball’s cover. Wilson dubs this the “carcass.”
The mix of styrene-butadiene rubber with natural rubber, which is quite lively, offers the rebound Wilson is looking for. The exact grades of rubber and mix is a ratio the team has massaged over time.
Krysiak says that while 80 percent of the rebound is determined by the internal ball pressure, 20 percent comes from the materials. “You are very much depending on the internal pressure, but there are little nuances we have learned over time that can get us an extra half inch, inch, or inch-and-a-half that we have optimized to meet the performance needs of the players,” he says.
The two-part carcass mold covers the winding layer and goes through its own vulcanization run of 150 to 160 degrees Celsius for about eight minutes. During that time, the hot rubber flows into the winding, giving additional structure to the ball, like rebar in concrete. “How much does it flow into the winding layer and how much does it sit on top of the windings is something we have learned and picked up over time,” Krysiak explains.
When removed from the mold, clean-up and buffing is required to get the carcass ready for the cover layer. The carcass layer also comes with raised channels, allowing the eight distinct cover panels to go on between the raised areas that form the black channels seen on the finished product.
NBA players are touching 100 percent genuine leather.
The cover material can have a slight impact on the bounce, but the main functionality is feel. “The biggest thing players are looking for is how does it feel when dry or when sweaty and wet,” Krysiak says. “In game performance, it is the one thing we tend to focus the most on.”
Chicago-based Horween, founded in 1905, is responsible for the leather. Using the meat industry’s byproduct steer hides, Horween does an initial chrome-tanned step, preserving the hide enough to be graded based on grain clarity. Once Horween gets the leather to the size and thickness needed for a basketball—about 2 millimeters in the Horween factory, although the finished product goes on a ball at about 1.4 millimeters—the hide is retanned with a blend of tree bark extracts and emulsified oils designed specifically for an NBA ball.
Then, the leather is dried in a pasting unit, with starch paste sticking to glass frames that allow the leather to run through a hot-air drier. After that comes the embossing process to create the pebbled texture.
Overall, there is about an eight-step process involved in treating the leather that also includes surface-dyeing the finish for a stain and pigment (heavy on stain) meeting Wilson’s specs.
“This ultimately is a performance product and the better someone is at something, the more they can tell and distinguish the subtleties,” Skip Horween tells Popular Mechanics. He notes that the high amount of tanning solution used as part of the Horween tannage allows the leather to take on the pebbling that gives the ball its texture. It is a finish system they developed with Wilson “to make the ball look and feel the way they want it to look and feel.”
“Our ultimate boss is the player,” Horween says. “The combination of the efforts of both companies and these recipes we have developed and evolved are customized.”
New Wilson balls come in a brand-chosen shade of orange, which is baked into the Horween process. Leather, with pores like a human skin, will absorb sweat, oils, and dirt from players’ hands, allowing the color of the ball to darken over time. The raised pebbles on the ball also tend to flatten with use.
Adding the pebbling at the Horween factory involves using an embossing press with a specific plate. “It is a close cousin of the football leather,” Horween says, “but it is definitely not the same. You would probably not play this leather on a football and not play football leather on a basketball.”
Once the finished product leaves Wilson, NBA teams have their own processes for breaking in the ball. Getting the right feel is a subjective process. Games aren’t played with new balls, but ones broken in over time. “Once it is broken in, it is good for a good, long while,” Horween says.
Krysiak says that when a team gets a ball to what they deem the perfect feel, Wilson asks for them to ship it back so they can do testing on it to define the specifications and create new data points.
“It is a very unique feel,” Krysiak says about the genuine-leather ball. “The NBA players tend to equate that completely different feel to the idea that they’ve made it.”
For both Krysiak and Horween, there’s a personal level of having made it, too. “For us, it is always a great privilege when a customer gives us the opportunity to do something like this that when we put our heads together, we get something special,” Horween says. “It is totally amazing to turn the TV on and see a ball and think we played our small part in making it happen.”
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