Geology’s Grip on Baseball - Investigating the Sedimentology, Mineralogy, and Physical Properties of Baseball Rubbing Mud

Oct 12, 2026

Uploaded by Aria

Major League Baseball prepares baseballs by rubbing them with a proprietary mud intended to improve grip and add color while maintaining league-wide consistency. Despite its long-standing use, the mud’s geologic characteristics and their precise effects on ball performance remain insufficiently understood. This study analyzes mineralogy and physical properties of rubbing mud within a depositional setting in a Delaware River tributary near Philadelphia, combining SEM and XRD with PSD and Rock-Eval. Results show mainly non-swelling clays and quartz, with clays accumulating in pores for coloration and quartz providing minor surface scouring and limited grip enhancement without major aerodynamic change.

LanguageEnglish

CategoryGeneral

FormatPDF

Pages10

Reading Time4 min

AccessFree to download

Introduction

Research approach and questions

Analytical methods

Results and implications

Research Article Geology’s Grip on Baseball: Investigating the Sedimentology, Mineralogy, and Physical Properties of Baseball Rubbing Mud Dallin P Laycock, Ph. D.1, Emily Vanderstaal, Bsc.2, Erin A Pemberton, Ph. D.1, Paul M Bremner, Ph. D.3, Richard Mackenzie III4, Han Byul Woo, Ph. D.3, Cory Twemlow, BSc.2, Sean Fletcher, MSc.5 1 Geology in Motion, 2 AGAT Laboratories, 3 NASA, 4 BOEM, 5 Strathcona Resources Keywords: Mud, Sedimentology, Baseball, Geology, Delaware River, XRD, SEM [https://doi.org/10.2110/001c.144870](https://doi.org/10.2110/001c.144870) The Sedimentary Record Vol. 23, Issue 1, 2025 Major League Baseball (MLB) prepares a minimum of 156 baseballs for each game by rubbing them with mud, sourced from the same company since the 1950’s (Baseball Rubbing Mud, n.d.) . This mud is intended to add grip and color to the baseball in a way that ensures competitive consistency across the league. Despite its long-standing use, the geologic characteristics of this mud and its precise effects on the baseball are still poorly understood. In this study, we analyze the mineralogy and physical properties of the baseball rubbing mud in the context of its depositional environment in a tributary of the Delaware River near Philadelphia. Samples of game-used and new baseballs were analyzed with Scanning Electron Microscopy (SEM), along with SEM analysis of the un-applied mud. These data were supplemented with X-Ray Diffraction (XRD), Particle Size Distribution (PSD), and Rock-Eval of the mud itself. Results show that the mud is composed primarily of non-swelling clays (Kaolinite, Chlorite, and Illite/Mica) and quartz, with minor amounts of other components. SEM images show that the clays primarily accumulate in the pores, adding the desired color to the baseball, while the coarser quartz grains serve as a scouring material, inducing scratches, micro-cracks, patches of erosion, and occasional flaking of the leather. This provides minor grip enhancement to the ball without significantly altering ball aerodynamics. The lack of swelling clays also prevent overly slippery or inconsistent grip in the presence of moisture. While muds could be sourced from different locations, changing the location of mud collection would result in variations in composition, grain size, and color that could alter the grip and color uniformity in ways that could provide competitive inconsistencies. 1. Introduction In baseball, the friction between a pitcher’s fingers and the surface of the leather ball is a critical factor that significantly influences pitching performance. At the moment of release, the tangential force reaches its maximum and affects both spin rate and the translational direction of the ball (Kinoshita et al., 2017 and Yamaguchi et al., 2022) . Stronger grip on the ball generally leads to increased pitching accuracy and performance. As such, discrepancies between balls can create unfair competitive advantages. To enhance grip even further, pitchers have occasionally used foreign (i.e., sticky) substances such as pine tar and rosin on baseballs. In June of 2021, Major League Baseball (MLB) announced efforts on prohibiting foreign substances that alter the ball’s grip. In the wake of these changes, the average spin rate of fastballs fell by approximately 4%(Katz et al., 2021) . Along with eliminating foreign substances, MLB also standardized the methods of pre-game baseball preparation to prevent unfair competitive advantages. According to MLB regulation, prior to each baseball game, 13 dozen balls are prepared in advance for gameplay. Baseballs used in MLB games have traditionally been prepared with a specific rubbing mud to remove gloss from the surface of newly manufactured balls, intended to increase friction and improve grip (Yamaguchi et al., 2022) . This specific and MLB sanctioned mud is the Lena Blackburne Baseball Rubbing Mud, which is sourced from a single company that has been supplying the MLB with rubbing

FAQs

What problem does this study address about MLB baseball rubbing mud?

The study addresses the gap in understanding the mud’s geological characteristics and how they precisely affect the baseball surface and grip.

Which instruments were used to analyze the mud and the baseball samples?

The mud and samples were analyzed using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD), supplemented by Particle Size Distribution (PSD) and Rock-Eval. SEM was also used to examine the un-applied mud.

What were the main findings about the mud’s mineral composition and its effects on the ball?

The mud is primarily non-swelling clays (Kaolinite, Chlorite, and Illite/Mica) and quartz. Clays accumulate in pores to add color, while quartz grains create minor scouring that can induce scratches and micro-cracks, providing slight grip enhancement without significantly changing ball aerodynamics. The lack of swelling clays also helps prevent inconsistent grip in moisture.

Oct 12, 2026

Uploaded by Aria