The special mud used to rub Major League Baseball (MLB) baseballs has been a mystery for decades. But now, scientists have uncovered the secrets behind its “magical” properties. Researchers at the University of Pennsylvania conducted tests to study the mud, which comes from a secret spot along the banks of a Delaware River tributary in New Jersey.
They found that the mud has the perfect mixture of sticky clay and sand particles, which enhance the friction on the ball’s surface while spreading evenly. “It spreads like face cream, but it grips like sandpaper. It has this magical ability,” said Doug Jerolmack, a geophysicist at the University of Pennsylvania and co-author of the study.
The use of this mud in baseball dates back to the 1930s, after a wild pitch fatally struck Cleveland shortstop Ray Chapman in 1920. Various substances were tried to make baseballs less slippery, but none were successful until 1938 when Lena Blackburne, a Philadelphia Athletics coach, discovered the mud from his childhood in New Jersey.
Baseball’s secret mud properties revealed
Today, MLB mandates that at least 156 balls be prepared with this mud for every game, with each team purchasing tubs for $100 each. Jim Bintliff, a retired New Jersey printing press operator, collects and processes the mud monthly from his grandfather’s old fishing hole. The scientists who examined the mud were motivated by curiosity and set out to quantify its properties.
Using an atomic force microscope, they measured the mud’s stickiness. A rheometer was used to measure its viscosity, and a synthetic “finger” was created to estimate the friction between human skin and a baseball. Their findings showed that the mud’s unique properties are rare and highly sought after in fields like cosmetics.
Emanuela Del Gado, director of Georgetown University’s Institute for Soft Matter Synthesis and Metrology, noted that the mud’s properties, shaped by natural environmental factors, are complex and valuable. Despite MLB exploring synthetic alternatives, no suitable replacement has been found. The study’s conclusions support the mud’s continued use, echoing the sentiment held by ballplayers for over 80 years: “This stuff works,” Jerolmack said.
Noah Nguyen is a multi-talented developer who brings a unique perspective to his craft. Initially a creative writing professor, he turned to Dev work for the ability to work remotely. He now lives in Seattle, spending time hiking and drinking craft beer with his fiancee.
