Cricket Ball Maintenance Explained: Shining, Rough Side, Saliva Ban, and Reverse Swing

The cricket ball deteriorates over the course of an innings. Managing that deterioration — legally, to the fielding team's advantage — is one of the most complex strategic elements in Test cricket. The core principle: a cricket ball swings through the air when it is asymmetric — one side smooth (shiny), the other rough. By shining one side with sweat and maintaining it carefully, while allowing (or aiding) the other side to roughen naturally, the fielding team creates sustained asymmetry. This asymmetry drives both conventional swing (first 25-45 overs) and reverse swing (from approximately 45 overs onwards, when the ball is old enough).

Legal Ball Maintenance: What Teams Are Allowed to Do

ICC Laws of Cricket (Law 41.3 — Ball maintenance) allow: (1) Polishing the ball with sweat: players can rub the ball on their clothing and apply saliva (now banned — see below) or sweat to maintain the shine on one side. The shine on one face of the ball reduces air resistance on that side, creating a pressure differential that curves the ball in the air (swing); (2) Drying the ball: fielders can dry the ball with their clothing if it becomes wet; (3) Natural roughening of the un-shined side: teams allow the natural wear of the pitch, ground, and use to roughen the opposite side of the ball from the shiny face. This creates the asymmetry needed for swing; (4) The seam: the raised seam of the cricket ball creates turbulence and assists deviation off the pitch. Teams try to maintain the seam's upright position by not scratching it. Only the condition of the leather, not the seam itself, can be legally managed.

The Saliva Ban: Why It Was Introduced and Made Permanent

Saliva was traditionally used to polish the shiny side of the cricket ball — teams would apply saliva with their fingers and buff it to a high shine. The ICC temporarily banned saliva application in 2020 as a COVID-19 biosafety measure (saliva contains respiratory droplets — spreading it on the ball and between fielders was identified as a transmission risk). In 2022, the ICC made the saliva ban permanent: (1) The stated reason for permanent ban: research indicated that saliva had limited impact on swing compared to sweat, and the hygiene and behavioural aspects of saliva use were simpler to eliminate; (2) The impact on bowlers: most fast bowlers and analysts agree the saliva ban has reduced the effectiveness of conventional swing bowling slightly — saliva polished more effectively than sweat alone. However, the adaptation has been manageable (teams work harder to apply sweat, use more players in the shining rotation); (3) Legal alternative: teams now use sweat only for ball shine. This is applied from the forehead, neck, or other parts of the body. The process is effectively identical to saliva application except sweat is slightly less effective for creating shine.

Reverse Swing: What It Is and How Ball Maintenance Enables It

Reverse swing is a phenomenon that occurs with an old ball (typically 40-50+ overs into an innings in Tests): (1) Conventional swing vs reverse swing: conventional swing occurs when the shiny side is on the outside of the ball's curved path through the air — the ball swings toward the shiny side. Reverse swing occurs when (with an old, heavily worn ball) the ball swings in the opposite direction — toward the rough side. The physics: with an old ball, the rough side creates more turbulence than the shiny side. At high pace (140+ km/h), this turbulence difference generates swing in the reverse direction; (2) Conditions for reverse swing: (a) an old ball with clear asymmetry between one very shiny face and one very rough face; (b) high pace — reverse swing is primarily a fast bowler's weapon (below approximately 130 km/h, reverse swing is minimal); (c) dry conditions — reverse swing works best when the ball is dry rather than wet; (3) Great reverse swing practitioners: Wasim Akram and Waqar Younis (Pakistan, 1980s-2000s) are the masters of reverse swing — they could reverse the ball at pace consistently, a skill that made them among cricket's most devastating bowling partnerships. James Anderson (England), Dale Steyn (South Africa), and Bhuvneshwar Kumar (India) are modern practitioners; (4) Why maintenance matters: the team that maintains the ball correctly — maximising shine on one side, allowing the other to roughen — is the team that can use reverse swing. Teams who fail to maintain the ball (both sides become equally worn) lose the reverse swing opportunity.