Jim Bintliff works in a secret waterway in southern New Jersey that has provided mud for Major League Baseball games for nearly 80 years. (Coke Whitworth/Associated Press)

A few times each fall, before the ground freezes and the air gets too cold, Jim Bintliff takes a shovel and buckets down to the banks of a muddy river in southern New Jersey. He’s there to harvest mud — odorless and puddinglike, with a chocolate color to match — that has become as much a part of Major League Baseball as Cracker Jack and batting helmets.

His Lena Blackburne Baseball Rubbing Mud is applied to every baseball used in a big-league game, to help pitchers grip the ball better as they launch it toward home plate.

“When fresh baseballs come out of the box, they’re quite slick. For a pitcher, that equals danger,” says Shawn Kelley, a Washington Nationals reliever who will be in the bullpen Monday for Opening Day. “If a pitcher were to throw a brand-new baseball, most would tell you they couldn’t be assured that it would even end up over the plate.”

In August 1920, Cleveland Indians shortstop Ray Chapman died after being hit in the head by a pitch from Carl Mays, a New York Yankees right-hander. It was the first and only time in MLB history that a player has been killed by a pitch, and it led the league to look for new ways to protect batters and improve pitch accuracy.

Balls began to be rubbed with mud, clay, shoe polish or tobacco juice, but the homemade mixtures often damaged the balls’ leather, turned it black or simply smelled bad. Blackburne, a third-base coach and former infielder, began using a better product in the late 1930s: mud that he found near his childhood home of Palmyra, New Jersey, where the slope of a riverbank that sent water into the nearby Delaware River formed a natural goop with a thick, baseball-friendly consistency.

Washington Nationals relief pitcher Shawn Kelley says brand-new baseballs are difficult to throw with accuracy. (Jonathan Newton/The Washington Post)

The magic mud soon spread through baseball’s American and then National leagues. Bintliff, 60, said he and his wife, Joanne, now sell about 2,000 pounds of mud each year, to every MLB team as well as to minor-league and college squads. The business has been in the family for three generations, ever since Blackburne passed it along to Bintliff’s grandfather, a close friend.

“There’s an art to harvesting mud,” Bintliff told KidsPost last week. He usually wades knee-deep into the muck, which he said is on public land, and shovels near the surface. If he goes any deeper, the mud becomes black and begins to smell.

To perfect his product, Bintliff ages the mud in 35-gallon trash cans for about six weeks before sending it on to buyers. (A “personal size” half-pound container of mud sells for $24.) Each MLB team gets 12 pounds for spring training and the regular season, he said.

Dan Wallin, the Nats’ equipment manager, said it takes him or a clubhouse assistant about 45 minutes to rub the mud on the 12 dozen baseballs that are prepared for a game. Applying the brown stuff can “make it harder for a hitter to see the ball,” he said, so he and his staff try to find a nice middle ground “where the pitchers like it and the hitters don’t complain.”

Rawlings, a sporting-goods company that makes all of the hand-stitched baseballs used in MLB games, is working on a new ball “that is easier to grip and does not require rubbing with mud,” according to an MLB spokesman. The experimental ball “would change things” for Lena Blackburne, Bintliff said, but in the past decade, he’s also found surprising new customers: pro football teams.

The National Football League did not immediately answer a request for its comment, but Bintliff said that about half of NFL teams buy Lena Blackburne mud to help their players grip the ball. So his business, which he plans to pass along to a daughter, may not dry up anytime soon.