Depending on how the ball is held and released, the new ball swings(i.e. moves in the air) towards the batsman or away from him.When the ball becomes older and gets scuffed up, it moves in the direction of the non-shiny side.The fielders try to keep one side of the ball shiny by applying sweat and saliva.
Fro Example, when bowling an inswinger to a right-handed batsman with an older ball, the bowler holds the ball in such a way that the scuffed-up side faces towards the batsman- then the ball will swing into the batsman. This is conventional swing.
It disappears when the ball gets old.Skilful bowlers then try to reverse-swing the ball : now the ball moves in the direction of the shiny side.
There are two key factors:
- The shiny side of the ball is wetter and heavier due to the constant application of sweat and saliva, while the scuffed up side is dry and lighter.
- The shiny side of the ball, because of its smoothness, offers lesser resistance to the ball than the rough side.
INCIDENTS OF BALL TEMPERING IN HISTORY:-
- John Lever (1997)
In January 1997, India captain Bishan singh bedi made a sensational allegation: That England fast bowler John Lever had been applying face cream(Brand:Vaseline) on the ball to shine it. Lever's defence was that he had used coton gauze soaked in vaseline over his eyebrows to stop sweat getting into his eyes, and some traces of the cream had been tranfered to the ball.