Foreign Material (Rule 4-2b)
|Foreign material must not be applied to the club face for the purpose of influencing the movement of the ball.
The Committee uses this Rule when materials of a temporary nature have been applied to the face – such as saliva, grass juice, chalk, aerosol spray or similar substances. Permanent attachments or coatings such as plasma spray,"balata"-type rubber or paint are dealt with under the club face Rules in Appendix II, 5 (see Section 9 below).
The most important question to ask when ruling on a club which has had something temporarily applied to the face by a player is "why has it been put there?" If a material or substance has been applied to the face in order to protect it or clean it, then it would probably be permitted provided all other Rules are satisfied. However, if the purpose of the application is to influence the movement of the ball or assist the player in making a stroke, it would be prohibited.
Any type of tape or similar material added to the face is not permitted for any purpose.