Baseball's Dirty Secret Comes From a Hole in the Ground
Every Major League baseball is rubbed with mud harvested from one secret New Jersey location, a supply chain that has lasted for generations.
Before every Major League game, clubhouse staff rub new baseballs with Lena Blackburne Baseball Rubbing Mud so the factory gloss comes off and pitchers can grip the ball. MLB has required this pregame "properly rubbed" prep for decades under Rule 4.01(c), and league reporting plus recent research still describe the same long-running New Jersey mud supply as standard practice.
The story begins with a death. In 1920, a pitch to the head killed Cleveland Indians shortstop Ray Chapman, the only on-field fatality in major league history. In the years that followed, baseball made changes to improve player safety, including a rule requiring umpires to remove dirty or scuffed balls from play and replace them with clean ones. But new baseballs had a problem. Straight from the Rawlings factory, they were slick and glossy, difficult for pitchers to grip. A pitcher who couldn't grip the ball couldn't control it, and an uncontrolled pitch at 90-plus mph was exactly the kind of thing that killed Chapman.
Teams tried everything to take the shine off. They rubbed the balls with infield dirt, but it scratched the leather. They tried tobacco juice, but it stained the balls too dark for hitters to see. They tried shoe polish. Nothing worked well enough.
In 1938, former player and Athletics coach Russell Aubrey "Lena" Blackburne remembered a mud from his childhood in Palmyra, New Jersey. Growing up, he had waded in a tributary of the Delaware River and noticed that the tidal mud had an unusual quality. It was fine-grained, smooth, and slightly gritty. That texture dulled the shine without ruining the leather.
Blackburne went back to the creek, scooped up some mud, brought it to the Philadelphia Athletics' clubhouse, and gave it to umpire Harry Geisel. Geisel rubbed it on a baseball. The gloss came off without scratching the leather or discoloring the cover. The American League adopted it almost immediately. The National League followed about a decade later. By the 1950s, every team in professional baseball was using Blackburne's mud.
When Blackburne got too old to harvest the mud himself, he passed the business to his childhood friend John Haas. Haas passed it to his son-in-law, Burns Bintliff. Burns passed it to his son Jim Bintliff, who has run the operation for decades. Public accounts and recent sedimentology research both describe one family company supplying MLB since the 1950s.
The exact harvest location is a family secret. Public reporting places it along a Delaware tributary in South Jersey, but the company doesn't publish the precise coordinates.
In 1982, the New York Times commissioned a geological analysis of the mud. Princeton geologist Dr. Kenneth Deffeyes examined a sample and found that more than 90 percent of it was finely ground quartz, likely crushed by glaciers during the Pleistocene Epoch more than 10,000 years ago. In 2024, researchers at the University of Pennsylvania became the first to empirically prove that the mud actually works, designing tests with a synthetic rubber "finger" to measure its friction-enhancing properties.
MLB has tested alternatives, including standardized prep protocols and other tack treatments, but the league still uses mudded balls in regular-season play. As of 2025 published research and league guidance, there was no adopted full replacement in MLB games.
"It's the history and the tradition," he has said. "Every ball, every game, every day."