Composition and microstructure of “Magic Mud”: (Top right) Clean baseball surface. (Bottom right) A baseball covered in mud.
Credit: S. Pradeep et al., 2024
Pradeep et al. We discovered that the particles of magic mud are primarily silt and clay, with small amounts of sand and organic matter. Stickiness comes from clay, silt, and organic matter, but sand makes it gritty. Therefore, they write, this mud “has the properties of a skin cream.” “This allows you to hold it in your hand like a solid, but it spreads easily and penetrates your pores to form a very thin coating on a baseball.”
But when the mud dries on the baseball, the residue it leaves behind is nothing like skin cream. This is because the angular sand particles are bound to the baseball by clay, which can increase surface friction by as much as two times. On the other hand, finer particles double the adhesion force. “The relative proportions of cohesive particles, abrasive sand, and water combine to create a material that is fluid like skin cream but grips like sandpaper,” the researchers wrote. .
Despite its relatively common components, this magical mud exhibits surprising mechanical behavior that the authors believe could also be useful for other practical applications. For example, if gritty sand particles are removed, they could replace synthetic materials as effective lubricants. Alternatively, it can be used as a friction agent to improve traction on slippery surfaces. However, the optimal proportion of sand content can be defined without compromising its malleability. Alternatively, it may be used as a binder for locally sourced geological materials for construction.
“As for the future of Loving Mud in Major League Baseball, unraveling the mysteries of its behavior will not and should not necessarily lead to synthetic replacement,” the authors concluded. “We rather believe the opposite. Rubbing mud is a naturally derived material that is replenished by the tides, and only a small amount is needed to achieve a great effect. We are moving towards an environmentally friendly solution. In one world, this seemingly outdated baseball tradition offers a glimpse into the future of Earth-inspired materials science. ”
Doi: PNAS, 2024. 10.1073/pnas.241351412 (About DOI).
