Ball Polishing in Cricket: The Art and Science of Maintaining Shine
How and why cricket teams polish one side of the ball while allowing the other to roughen — the aerodynamic physics of differential roughness and polish, which players are responsible for ball maintenance, why saliva was banned (COVID-19 protocols), what replaced it, and how ball condition affects bowling options across the match.
Why Shine Matters
A new cricket ball has a uniform lacquered shine on both sides. From the moment play begins, the ball's surfaces begin to deteriorate differently: the side that encounters the pitch on seam deliveries remains rougher (the ball's equatorial seam creates a consistent rough-landing pattern), while the side without the seam can be polished by the fielding team to retain its shine. This differential — one shiny side, one rough side — is the essential prerequisite for conventional swing bowling.
The aerodynamic principle: the shiny side of a cricket ball in flight experiences less turbulent airflow (the boundary layer remains attached to the smooth surface for longer, creating a region of low pressure). The rough side experiences turbulent airflow earlier (the rough surface triggers the boundary layer to separate sooner, creating a relatively higher-pressure region). The pressure differential across the ball's two sides creates a net lateral force — the ball swings toward the rough side (in conventional swing) or away from it (in specific conditions where the seam is angled differently).
Who Polishes the Ball
Ball polishing is traditionally done by every fielder who handles the ball between deliveries — a constant chain of maintenance that involves rubbing the smooth side against clothing (typically trouser thighs or shirt fabric) to restore moisture and shine. The designated ball-shiners on most teams are the pace bowlers who will be using the swing — they have the strongest motivation to maintain shine and the most experience knowing which side needs attention at any given point in the innings.
Historically, players used saliva (spitting on the ball and rubbing) as the primary shining medium — saliva's slightly acidic, protein-rich composition was considered optimal for maintaining leather shine over extended periods. In March 2020, the ICC suspended the use of saliva on the ball as a COVID-19 infection control measure. The ICC subsequently considered making the ban permanent, citing the difficulty of monitoring whether any applied fluid was 'pure saliva' or contained illegal substances. As of 2022-2023, ICC playing conditions allow sweat (applied without artificial aids) but not saliva.
Ball Condition Across an Innings
Ball polishing and maintenance follow a predictable pattern across an innings. In the first 10-15 overs, the new ball is hard and shiny on both sides — conventional swing is possible. From approximately overs 15-35, one side has been polished by the fielding team while the other has roughened naturally — the maximum differential condition for conventional swing. From approximately overs 35-50 (ODI) or 50-70 (Test), the ball softens and both sides become similarly rough — conventional swing diminishes. In Tests and ODIs where the innings extends long enough, the highly developed rough side and still-maintained shiny side can produce reverse swing (the opposite swing direction to conventional).
Frequently asked questions
Is there any legal substance teams can apply to the ball to help it swing?
Only natural body products — sweat from the player's body, applied directly without intermediary substances — are permitted. Applying any artificial product (sunscreen, lip balm, wax, artificial lubricants) to the ball is ball tampering under Law 41 and results in a 5-run penalty and potentially further sanctions. The Pakistan Sandpapergate incident of 2018 (in South Africa) involved artificially roughening the ball with sandpaper — the opposite intervention to shining, but similarly illegal. Legal ball maintenance is confined to the natural shining effect of hand sweat applied by rubbing.
Why does the rough side help produce reverse swing?
In conventional swing, the rough side creates a high-pressure region that pushes the ball toward it. In reverse swing, the ball travels fast enough (typically 130+ km/h) that the aerodynamic pattern inverts: at higher speeds, the rough side's turbulent boundary layer actually reduces the drag coefficient compared to a laminar flow over the rough surface — the physics of boundary layer transition shifts above 130 km/h. The precise speed threshold for reverse swing depends on ball condition, atmospheric conditions, and seam angle. Pakistan bowlers of the 1980s-90s (Wasim Akram, Waqar Younis) developed the mastery of reverse swing as a specific art.
How does the two-ball system in ODIs affect ball maintenance?
Since 2012, ODIs use two new balls simultaneously — one bowled from each end. Both balls are maintained by the fielding team, though they deteriorate at different rates (one may shine better than the other depending on which bowlers use each end and how each ball lands on the pitch). Two-ball ODIs eliminate the soft-ball phase (overs 35-45 under the old one-ball system when the ball was very soft and spinners dominated) and reduce the window for reverse swing (the balls stay newer throughout). This has been a primary driver of increased ODI scores since 2012.