The Science That Makes Baseball Mud ‘Magical’

Scientists dug up the real dirt on the substance applied to all the baseballs used in the major leagues.

If you looked closely at the baseballs used in the World Series last month, you would notice that they were covered in a mysterious brown substance.

It was not a mistake, and nothing illegal was found on the balls. It was just mud.

For decades, all the balls used in Major League Baseball have been coated with mud harvested from a secret spot along a Delaware River tributary in New Jersey. Only a few people knew of the exact location and until recently, and only a few knew the exact contents of that mud.

Now researchers have dug deep and found what they consider to be remarkable mechanical properties of this mud.

“This is the magical thing: It spreads like face cream and grips like sandpaper,” said Douglas Jerolmack, a professor of earth and environmental science at the University of Pennsylvania and one of the authors of a paper published on Monday in The Proceedings of the National Academy of Science.

Their research may be well suited for more than just studying baseball. The researchers say that the techniques they used to understand how baseball mud works could be extended to the development of sustainable materials for construction, agriculture and infrastructure.