Over the course of a typical Major League Baseball (MLB) game, the two teams will use well more than 50 baseballs. Some balls go into the stands and become souvenirs for lucky fans, of course, but there are times when the balls simply get so scuffed during game play to warrant a replacement. The baseballs have to be in great condition to be usable — we don’t want a low quality ball interfering with the game’s outcome.

So you’d expect that MLB games use brand new, fresh-from-the-box ones. They do, but there’s a problem with new balls; it turns out that baseballs aren’t sold in ready-to-use condition — not, at least, if you’re a Major League caliber pitcher. Factory-sealed baseballs are a little too perfect. They’re coated in a shiny gloss which makes them look great on a store shelf, but, unfortunately, makes them a little hard to grip, especially if you’re trying to throw an 80 mile an hour curve ball through an invisible target the size of a mini-fridge. The baseballs need further processing and care: they need to get a little dirty.

As in: someone needs to literally rub the balls with dirt.

And not just any dirt will do. It has to be special. Luckily, MLB has a connection — there’s a company which, every year, provides special mud to the league. Before each game, one of the umpires (or someone from the stadium staff) takes these five dozen or so balls and rubs each and every one of them with a Lena Blackburne Baseball Rubbing Mud, named for a coach who, apparently, discovered this special mud in the 1930s.

Where did Blackburne find it? That’s a secret the company won’t share.

Well, the specifics are a secret, at least. We know that the company sources its mud from the Delaware River basin, as the Christian Science Monitor reported, and likely from a tributary near Delran, New Jersey, per another source. Jim Bintliff, the owner of the company (and a descendant of Blackburne), won’t reveal his secret source. He does, however, have no problems explaining what makes the mud special — it is very fine, with the consistency of chocolate pudding, which — he claims — makes it able to remove the sheen without damaging the leather, something no other mud can do quite as well.

That may be more tradition than science — MLB has been using Lena Blackburne Baseball Rubbing Mud since the 1950s or so, and it’s likely that the composition of the mud has changed over time, and similarly likely that the process of making a baseball has changed as well. That being the case, some may question why MLB insists on giving Lena Blackburne a monopoly on the ball treatment dirt. But don’t think this is some sort of big moneymaker. Blackburne sells a 32-ounce container of the mud for about $50, and that’s enough to last an MLB team an entire season. Including all the minor league and college teams which buy the special mud, the company only sells about $25,000 worth of mud each year.

Bonus Fact : The mud isn’t the only thing special about the de-sheeining of a baseball. The balls also have to be “properly rubbed” — a phrase right out of MLB’s official rule book (pdf here; it’s on page 24). Rule 3.01 starts by noting that “before the game the umpire shall” do a number of things, and subpart (c) references the mud-rubbing. And apparently, that’s a pretty big deal. The Christian Science Monitor explains in the story linked-to above: “There’s a special technique to rubbing up a baseball. The mud – and a little water – goes on the leather, but not the seams. If it’s not done right, the pitcher will throw the ball back to the umpire. ‘If you don’t apply the mud uniformly,” warns [Nick Zibelli, director of umpiring for the Eastern College Athletic Conference], “the pitcher can’t get the proper grip. At 90-plus miles per hour, it doesn’t take much to throw the tracking off.”

Double bonus!: Every single one of the baseball uses by MLB comes from the same factory in Costa Rica — and every single baseball is hand-stitched. There have been some efforts to automate the manufacturing process entirely, but for reasons unclear, technology can’t properly duplicate the stitching process — it takes a human touch. The Costa Rican factory employs 300 people who, collectively, produce 2.4 million such baseballs a year.

From the Archives: One Spud You’re Out: It’s about baseball, but not about a baseball.

Related: “Miracle Mud,” a kids’ book about the Lena Blackburne rubbing mud. Also, an official MLB baseball. Hand-stitched, but needs mud.