Mud: The Magic Ingredient for a Better Grip?

On a cool September day in 1965, John Haas took his grandson Jim Bintliff, to a special spot. Bintliff, who was 9 years old at the time, helped load a shovel and an old metal camping kettle into his grandfather’s car, and they headed off. After a short ride, they parked and walked to an area along the Delaware River in southern New Jersey where Bintliff’s grandfather used to swim and fish with his friends as a kid.

The ground was waterlogged, and their feet squished in the mud. This sticky sludge was what they had come for. The two took turns shoveling the mud into the kettle until it was full to the brim. Then they latched the lid and carried their haul back to the car.

Bintliff’s grandfather had been gathering what he called “magic mud” from this secret place for about 30 years. He was in the business of selling it, mostly to one group of customers: professional baseball teams. It turns out this mud has been a game changer for the sport.

It was a cool September day in 1965. John Haas took his grandson, Jim Bintliff, to a special spot. Bintliff was 9 years old. He helped load a shovel and an old metal camping kettle into his grandfather’s car. Then they headed off. After a short ride, they parked and walked to an area along the Delaware River in southern New Jersey. When Bintliff’s grandfather was a kid, he used to swim and fish there with his friends.

The ground was soaked, and their feet sank in the mud. But this sticky muck was what they wanted. The two took turns shoveling the mud into the kettle until it was full. Then they latched the lid and carried it back to the car.

Bintliff’s grandfather called this “magic mud.” For about 30 years, he had been gathering it from this secret place. His business was to sell it, mostly to one group of customers. They were professional baseball teams. That’s because this mud has been a game changer for the sport.

Major League Baseball (MLB) started in the early 20th century. Since then, the league’s pitchers have been trying to give the smooth surface of a new ball more grip. A good hold helps improve the accuracy of their pitches. In the early days, pitchers tried to add texture to a ball’s surface by scratching it with sharp tools and scuffing it with sandpaper. This would increase the amount of friction—a rubbing force that resists motion—between a pitcher’s hand and the ball. Pitchers tried things like rubbing the ball with dirt from the baseball diamond and even coating it with shoe polish. But nothing worked well.

By the 1930s, MLB started to look for one consistent way to improve grip. But league officials didn’t want to overdo the amount of friction. This would allow pitchers to put an unfair amount of spin, or rotations per minute, on the ball. That, in turn, would make the ball’s trajectory, or curved path, unpredictable—and almost impossible for batters to hit.

In 1938, Russell “Lena” Blackburne, a third-base coach for the Philadelphia Athletics, learned about MLB’s search. He overheard two umpires discussing how the league was looking for a way to improve the grip on a baseball after a wild pitch tragically killed a player. Blackburne thought about the mud on the banks of the Delaware where he and his friend John Haas—Jim Bintliff’s grandfather—played as kids. He recalled how the mud felt silky smooth when wet but coarse and grainy after it dried. Blackburne gathered some of the mud and rubbed a dollop all over a new baseball. The grip was perfect.

Eventually, every team wanted it. Because of its popularity, Blackburne enlisted Haas to help collect and sell the mud. Haas eventually took over the business, which he passed down to his daughter. She then passed it down to Bintliff. The business has now been in the family for almost 90 years! “I love the history of it,” says Bintliff. To this day, each of the estimated 300,000 balls used during an MLB season is treated with Lena Blackburne Baseball Rubbing Mud.

Major League Baseball (MLB) started in the early 20th century. Since then, the league’s pitchers have tried to add more grip to a new ball’s smooth surface. A good hold leads to more accurate pitches. Early on, pitchers scratched the ball with sharp tools and sandpaper. They wanted to add texture to the surface. This would increase the amount of friction between a pitcher’s hand and the ball. Friction is a rubbing force that resists motion. Pitchers tried different things. They rubbed the ball with dirt from the baseball diamond and even coated it with shoe polish. But nothing worked well.

By the 1930s, MLB started to look for one consistent way to improve grip. But league officials didn’t want to add too much friction. If they did, pitchers could put an unfair amount of spin on the ball. It would rotate too many times per minute. Then the ball’s trajectory, or curved path, would be unpredictable. It would be almost impossible for batters to hit.

Russell “Lena” Blackburne was a third-base coach for the Philadelphia Athletics. In 1938, he learned about MLB’s search. A wild pitch had killed a player, and so the league was looking for a way to improve the grip on a baseball. Blackburne overheard two umpires talking about it. He thought about the mud on the banks of the Delaware. As a kid, he had played there with his friend John Haas. That was Jim Bintliff’s grandfather. Blackburne recalled that the mud felt silky smooth when wet. But it was coarse and grainy after it dried. He gathered some of the mud and rubbed a little all over a new baseball. The grip was perfect.

Eventually, every team wanted it. Because it was so popular, Blackburne got Haas to help collect and sell the mud. Haas later took over the business. He passed it down to his daughter. Then she passed it down to Bintliff. Now the business has been in the family for almost 90 years! “I love the history of it,” says Bintliff. Today about 300,000 balls are used during an MLB season. Each one is treated with Lena Blackburne Baseball Rubbing Mud.

Because the rubbing mud is in such high demand, Bintliff’s family has kept the exact location of its source a secret all these years. But is there really anything special about the mud? Douglas Jerolmack, a geophysicist from the University of Pennsylvania, decided to find out. He usually studies soils and sediments—materials such as sand or rock that are moved by water or wind. But “when I was contacted by a sports journalist for my opinion about the baseball mud, I was intrigued,” says Jerolmack.

The rubbing mud is in high demand. So Bintliff’s family has kept the exact location of its source a secret all these years. But is there really anything special about the mud? Douglas Jerolmack decided to find out. He’s a geophysicist from the University of Pennsylvania. Jerolmack usually studies soils and sediments. Sediments are materials like sand or rock that are moved by water or wind. “When I was contacted by a sports journalist for my opinion about the baseball mud, I was intrigued,” he says.

Shravan Pradeep, who is part of Jerolmack’s team, tested the mud just like he would any sample—by using an instrument to count, measure, and identify its microscopic particles. “There was nothing in there that was surprising,” says Jerolmack. The mud was nearly half water and the rest was particles of sand and clay common to riverbeds in the region.

Next, the team examined the surface of a clean ball and a muddied one under a high-powered microscope. Unlike the clean ball, the surface of the mud-covered one resembled fine sandpaper. They found that none of the gritty particles stuck to its surface were larger than 169 micrometers—about the thickness of a sheet of paper. This was likely because of the way Bintliff prepares the mud (see Making Magic Mud). Filtering it leaves behind tiny clay particles and sand particles that coat the ball. Adhesion—attraction between different substances—increases because of “clay particles, which are a bit sticky,” explains Jerolmack. Meanwhile “friction arises due to the slightly larger sand particles sticking out from the ball like barnacles.”

The team found that this mix of particles helps to double adhesion and friction compared with a clean ball (see Grip Test). But if the particles stuck to the ball were any larger, a pitcher’s grip on a ball could be unfair. This would allow players to throw unhittable pitches.

Shravan Pradeep is part of Jerolmack’s team. He tested the mud just like any sample. He used an instrument to count, measure, and identify its microscopic particles. “There was nothing in there that was surprising,” says Jerolmack. The mud was nearly half water. The rest was particles of sand and clay. They’re common to riverbeds in the region.

Next the team used a high-powered microscope. They examined the surface of a clean ball and a muddied one. Unlike the clean ball, the surface of the mud-covered one looked like fine sandpaper. Gritty particles were stuck to its surface, but none was larger than 169 micrometers. That’s about the thickness of a sheet of paper. This was likely because of the way Bintliff prepares the mud (see Making Magic Mud). He filters it, and tiny clay and sand particles are left behind. They coat the ball. Adhesion is the attraction between different substances. It increases because of “clay particles, which are a bit sticky,” explains Jerolmack. And “friction arises due to the slightly larger sand particles sticking out from the ball like barnacles.”

The team compared the results with a clean ball. They found that the mix of particles on a muddied ball helps to double adhesion and friction (see Grip Test). A ball coated with larger particles would make the pitcher’s grip unfair. Then players could throw unhittable pitches.

Jerolmack’s analysis proves that the mud is special after all. “I’ve never had a real good explanation of how or why it works,” says Bintliff. He reached out to Jerolmack to thank him for providing evidence that his product does what it claims.

“Of all the attention that we’ve gotten for the study, Jim’s response meant the most,” says Jerolmack.

Today a poster hangs in every MLB team’s clubhouse showing how to properly apply the mud so that each ball is as similar as possible throughout the league. It’s far from a perfect science, which is why MLB has been looking to replace the mud with a synthetic, or human-made, version for years. “We’ve had some very smart scientists spend a lot of time on this issue,” says Morgan Sword,  executive vice president of baseball operations for MLB. “But so far, nobody can beat the mud.”

Jerolmack’s study proves that the mud is special after all. “I’ve never had a real good explanation of how or why it works,” says Bintliff. The tests provide evidence that his product does what it claims. So he contacted Jerolmack to thank him.

“Of all the attention that we’ve gotten for the study, Jim’s response meant the most,” says Jerolmack.

Today a poster hangs in every MLB team’s clubhouse. It shows how to properly apply the mud. That way, each ball is as similar as possible all over the league. It’s far from a perfect science. So MLB has wanted to replace the mud with a synthetic, or human-made, version for years. Morgan Sword is MLB’s executive vice president of baseball operations. “We’ve had some very smart scientists spend a lot of time on this issue,” he says. “But so far, nobody can beat the mud.”