“As all true gentlemen cricketers know, only natural substances such as sweat or saliva can be legally used as a polishing agent, although the odd use of ‘Vaseline’ or ‘Brylcreem’ is often at the centre of a ball tampering controversy. “
And, as rule 41.3.2 of the ‘Laws of Cricket.’ clearly states :
“It is an offence for any player to take any action which changes the condition of the ball.”
Nevertheless, ‘illegal’ ball-tampering in professional cricket games is rarely out of the news.* see note. But, with regard to the physical laws of aerodynamics, do the tamperers really know what they are doing when, for example, they sandpaper balls or apply Vaseline™? An authoritative viewpoint was provided in 2000 by Rabindra D. Mehta of NASA Ames Research Center, California, US, in his essay ‘Cricket Ball Aerodynamics: Myth Versus Science’.
“The basic scientific principles of conventional swing are now well established and understood. However. some confusion still remains as to what reverse swing is, and how it can be achieved on a cricket field. While it is generally believed (with some justification) that tampering with the ball’s surface helps in achieving reverse swing, the exact form of the advantage is still not generally understood.
Needless to say, cricket ball aerodynamics would not be such a fascinating subject if all the mysteries and controversies could be readily answered and settled.”
Note * See, for example this 2018 video showing the effects that ball tampering can have on lachrymation . . .