Jim Bintliff has pretended to be a scientist, a college professor and a government geologist -- all for the sake of baseball.

"I don't like to lie to people," the Delran, N.J., resident said recently as he shoveled runny, brown muck from a creek into five-gallon buckets. "But if they see me out here, I have to make up something. I can't have people knowing this is where I get the mud."

From a secret location in southern New Jersey, Bintliff supplies the major, minor and international leagues with the dirty concoction that is rubbed on new baseballs before they are put into play. It takes off the sheen, softens the seams and gives pitchers better control.

"Lena Blackburne Baseball Rubbing Mud" has been used in the American League since the late 1930s and on every ball in the majors for the past 50 years.

According to Major League Baseball, umpires began rubbing mud into the balls in 1921 to remove the gloss. But they used infield dirt and water, with varying results.

In 1938, Russell "Lena" Blackburne, a former player who was a coach with Connie Mack's Philadelphia Athletics, joined the effort. He searched Burlington County's streambeds and found a suitable goo.

It covered the ball evenly without making the cover mushy. Umpires loved it, and the rest is history.

It took Blackburne, who didn't care much for National League teams, a couple decades to offer his mud to them. Major League Baseball has been using the stuff exclusively since the 1950s -- no other foreign substance can be applied to new baseballs before they are used.

Before he died in 1968, Blackburne passed the mud hole's location on to boyhood friend John Haas, who later passed the secret on to his son-in-law, Burns Bintliff.

Bintliff, who died three years ago, brought his son Jim into the business when the boy was about 8.

"Back then, we used a boat and would wade to the shore," said Jim Bintliff, 47, who now hoofs it to the hole.

The mud has been refined over the years. A secret organic ingredient is added to give it a fine grit.

Bintliff describes the finished mud as "a cross between chocolate pudding and whipped cold cream." He won't patent the product because that would mean the processing method would eventually be made public. Its cosmetic potential -- facial, anyone? -- is unknown.

"Nobody can match this mud," he said. "It only takes a dab to do a half-dozen balls."

Before home games at Citizens Bank Park, that job falls to Phillies assistant equipment manager Dan O'Rourke.

"Without the mud, the ball is much more slippery," he said.

He spends about half an hour rubbing up to 120 balls -- more than enough for the game.

"I'd be in trouble if we ran out," he said. "I wouldn't want to do that."

The mud mined today comes from a spot different from the one used by Blackburne, Bintliff said. About 25 years ago, development near the first hole made it impossible to keep the location a secret.

He makes up to six trips a year to the mud hole, working through the spatterdock (a water plant) to his special spot before collecting the syrupy top layer from underneath a foot or so of water.

"It's a pretty good day for mud," he said on a recent trip. "We caught the tide just right."

A reporter agreed not to divulge the location of the mud hole, which is along a South Jersey tributary of the Delaware River.

If people come upon him while he's there, he sizes them up to see what story he can sell them. Sometimes he simply uses one of his father's favorites -- an oldie but goody.

"I tell them I'm getting it for my rose bushes," he said.

He's not concerned about taking something from public lands. Nobody has ever challenged him on it.

"The amount that I scoop up is so small that you won't even be able to see where my shovel was once high tide comes and goes again," said Bintliff, a commercial printing press operator when he isn't harvesting mud. "As long as I pay taxes on what I sell, I don't think the government will give me a hard time."

The location is still a secret, but the price is no longer a mystery -- a 32-fluid-ounce container costs $45 and can be purchased by anybody, not just by ball clubs. Each major league team uses two per season, one at spring training and another for home games.

Last year he sold nearly 1,200 pounds.

"I'll never get rich doing this, but I get paid in more ways than money. My mud is on every ball and is a part of every milestone. I am part of baseball."

The mud Jim Bintliff takes from this creek is rubbed on new baseballs.Jim Bintliff's reflection can be seen as he harvests the mud that will be used at ballparks across the country. "Nobody can match this mud. It only takes a dab to do a half-dozen balls," says Bintliff, here taking away his haul.