Study: Special mud rubbed on MLB baseballs has 'magical' properties

A special mud gets rubbed on every baseball before every MLB game to make them less slippery. A new study explains the science behind why it works.

For more than 80 years, baseball has relied on a stash of special mud to take the shine off balls’ slick leather and give fielders a better grip. The substance is rubbed on every baseball before every major league game. Called Lena Blackburne Baseball Rubbing Mud, it comes from a single source: a secret spot along the banks of a tributary of the Delaware River. Jim Bintliff, a retired New Jersey printing press operator, collects the mud about once a month from his grandfather’s old fishing hole. He likens its consistency, after processing, to a “cold cream or maybe a stiff pudding.” 

Despite the mud’s ubiquity, no one had been able to explain the science behind why it makes balls easier to grip — or even provide empirical proof that it worked at all. Until now. 

Researchers at the University of Pennsylvania designed a series of tests to study the mud and even constructed a synthetic rubber “finger” to measure its characteristics. Their results, published Monday in the journal Proceedings of the National Academy of Sciences, offer the first published scientific evidence that the mud’s power is more than myth. 

“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 magic mud is applied to every ball used in Major League Baseball, including in this year’s World Series.Mark Griffey/Penn EngineeringJerolmack’s team found that the mud has the perfect proportions of sticky clay and particles of sand. The latter studs the surface of a ball like barnacles to enhance friction, yet the material still spreads thin and even, like toothpaste. “The more you push on it, the more it flows,” Jerolmack said.

https://www.nbcnews.com/science/science-news/why-baseball-mud-rubbed-on-balls-works-study-rcna178321

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