New York Times - "He’s Baseball’s Only Mud Supplier. It’s a Job He May Soon Lose."
"While coaching third base for the Philadelphia Athletics in 1938, he heard an umpire complain about the struggle to prepare brand-new balls for use. Blackburne experimented with mud from a Delaware River tributary, not far from his New Jersey home, and found that it de-glossed the ball while mostly maintaining its whiteness.
He now had a side job. After a while, every major and minor league team was using what sometimes came to be called “Mississippi mud” — though “mysterious” would have been more apt than Mississippi.
Before Blackburne died at 81 in 1968, he bequeathed the secret spot to an old friend who had joined him in mud harvesting: Bintliff’s grandfather, who left it to Bintliff’s mother and father, who, in 2000, passed it on to Bintliff."