Purpose: Rule 4 covers the equipment that players may use during a round. Based on the principle that golf is a challenging game in which success should depend on the player’s judgment, skills and abilities, the player:
a. Clubs Allowed in Making a Stroke
(1) Conforming Clubs. In making a stroke, a player must use a club that conforms to the requirements in the Equipment Rules:
• A club used to make a stroke must conform not only when the club is new, but also when it has been deliberately or accidentally changed in any way.
• But if the performance characteristics of a conforming club change because of wear through normal use, it is still a conforming club.
"Performance characteristics” means any part of the club that affects how it performs in making a stroke, such as its grip, shaft, clubhead or lie or loft (including lie or loft of an adjustable club).
It is the player’s own responsibility to ensure that his or her clubs conform to the Equipment Rules. If the player has any doubt as to the conformity of a club, he or she should consult The R&A or USGA. Queries may also be directed to the local committee in charge of a competition or the local Rules Committee.
There is a penalty of disqualification should a player make a stroke with a non-conforming club, but there is no penalty if a player merely carries a non-conforming club during the round. However, such a club still counts towards the 14-club limit (see Rule 4.1b(1)).
Over time, the face and grip of a club, in particular, may become worn through normal use. For example, a grip may become so worn that it becomes moulded for the hands, or the grooves on an iron club may become so worn that they no longer conform to the requirements in Part 2, Section 5c of the Equipment Rules.
A club that conforms with the Equipment Rules when new is deemed to conform after wear through normal use. In essence, the second bullet of Rule 4.1a(1) states that a club which conformed when new cannot be rendered non-conforming due to its wear through normal use. However, a club which did not conform to the Equipment Rules when new cannot be worn, through normal use, to a conforming state. Such a club would always be considered non-conforming. In general, “wear” is defined to be the erosion of material (as opposed to “damage”, which is usually caused by a single load or repeatedly applied loads). Material decomposition or deterioration is not generally considered to be wear.
When a used club is pendulum tested (see Part 2 Section 4c(i)) in the field and a result in excess of 257 µs is attained, the specific club will be deemed to be damaged into a non-conforming state, based on the presumption that it conformed when new and was included on the List of Conforming Driver Heads. As such, any individual club tested in excess of 257 µs will not be permitted to be used in play during any subsequent stipulated round since it does not conform to the Rules of Golf. The damage will be deemed to have occurred after the start of the previous stipulated round (i.e., prior to the field test), so that no retrospective penalties would be applied, unless the player had knowledge, prior to the field test, that the club did not conform.
Rule 4.1a continues
(2) Use or Repair of Club Damaged During Round. If a conforming club is damaged during a round or while play is stopped under Rule 5.7a, the player normally must not replace it with another club. (For a limited exception when the player did not cause the damage, see Rule 4.1b(3)).
Performance Characteristics Deliberately Changed
The purpose of this Rule is to penalize a player that purposely modifies his or her club during a round – for example to a flatter lie, a greater loft, an alternative weight distribution or changing the head or shaft, regardless of whether the club has been designed to be adjustable.
Additionally, this Rule penalizes a player that applies materials of a temporary nature 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 covered under Part 2, Section 5 of the Equipment Rules.
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.