Researchers from the University of Pennsylvania have unlocked the scientific secrets of Major League Baseball’s renowned “magic” mud, demonstrating its unique properties and potential applications beyond the sport.
Researchers at the University of Pennsylvania have unveiled the scientific properties that make Major League Baseball’s “magic” mud so effective, revealing insights that could extend beyond the sport. This mud, used on every ball in MLB games, including the World Series, has long been praised for its ability to enhance ball grip and performance. Now, the mystique surrounding this well-kept secret has been scientifically quantified.
In a newly published study in the Proceedings of the National Academy of Sciences (PNAS), a team from Penn’s School of Engineering and Applied Science (Penn Engineering) and the School of Arts & Sciences (SAS) dissected what makes this mud unique.
“It spreads like a skin cream and grips like sandpaper,” first author Shravan Pradeep, a postdoctoral researcher in the labs of Douglas J. Jerolmack, the Edmund J. and Louise W. Kahn Endowed Term Professor in Earth and Environmental Science (EES) within SAS and a professor of mechanical engineering and applied mechanics (MEAM) within Penn Engineering, and Paulo Arratia, the Eduardo D. Glandt Distinguished Scholar and a professor in MEAM and of chemical and biomolecular engineering (CBE).
Since 2019, at the suggestion of sportswriter Matthew Gutierrez, the team delved into the mud’s composition and characteristics.
The mud, sourced secretly by the Bintliff family in South Jersey for generations, is applied by each MLB team’s equipment manager to every game ball. While numerous accounts by players and published articles have praised the mud, scientific validation was absent until now.
“We provided a quick analysis, but not anything that rose to the level of scientific proof,” Jerolmack said in the news release.
Jerolmack initially suspected the mud’s reputation might be based on superstition. However, with the arrival of Pradeep in their lab, three detailed experiments were conducted to measure the mud’s spreadability, stickiness and effect on baseballs’ friction against fingertips.
“The question is, how do you quantify the friction between the ball, your finger and the little oils between those two?” added Arratia.
Existing tools like a rheometer and atomic force microscopy helped measure spreadability and stickiness. However, measuring friction required innovation.
Co-author Xiangyu Chen, a MEAM senior, developed an artificial finger setup with human skin-like elasticity and oil properties.
Through their experiments, the team determined that the mud’s unique composition indeed enhances performance — affirming long-held beliefs among players and equipment managers.
“It has the right mixture to make those three things happen — spreading, gripping and stickiness,” added Jerolmack.
MLB has considered synthetic alternatives but has yet to replicate the mud’s distinctive properties.
“This family is doing something that is green and sustainable, and actually is producing an effect that is hard to replicate,” Jerolmack added.
Beyond baseball, researchers aspire that their findings will pique interest in natural materials as potential lubricants.
“This is just a venue for us to show how geomaterials are already being used in a sustainable way,” added Arratia, pointing out that such materials might offer unique properties difficult to synthetically create.
This enlightening study represents a significant breakthrough, casting light on an age-old sports tradition and inviting further exploration of natural materials in various applications.