5. Club Face
Appendix II, 5a states that:
The face of the club must be hard and rigid and must not impart significantly more or less spin to the ball than a standard steel face (some exceptions may be made for putters). Except for such markings listed below, the club face must be smooth and must not have any degree of concavity.
If claims of excessive spin are made by the manufacturer, or if there is strong supporting evidence of excessive spin, then the club could be deemed to be non-conforming.
The "hardness" rule is particularly relevant to putters, many of which have urethane or other "soft" material inserted into the face.
The measure for "hardness" is made using a durometer. A putter face must have a hardness of no less than 85 on a Shore A scale durometer. A simple measure of hardness "in the field" would be to use a fingernail. If pressing a fingernail leaves a significant imprint in the face of a club, please consult the USGA and offer a Duration of Competition or Duration of Round ruling. The face of a wood or iron club must be substantially harder than a putter face, i.e., no less than 75 on a Shore D scale.
In the field, "rigidity" is interpreted to mean that the face should not have any visible signs of movement or flex when manual pressure is exerted.
When an insert is incorporated into the club face, it should be flush with the rest of the face so that the face is still considered smooth and not concave. While we interpret concavity in this provision strictly, we also recognize that, due to manufacturing tolerances, it is difficult for every insert to be exactly flush with the rest of the face. As a result, we allow an insert to protrude by as much as 0.006 inches (0.15 mm) or be sunken by as much as 0.004 inches (0.1 mm).
b. Impact Area Roughness and Material
Appendix II, 5b states that:
Except for markings specified in the following paragraphs, the surface roughness within the area where impact is intended (the "impact area") must not exceed that of decorative sandblasting, or of fine milling. The whole of the impact area must be of the same material (exceptions may be made for clubheads made of wood).
(i) Definition of ‘Impact Area'
The impact area for irons is that part of the club where a face treatment has been applied (e.g., grooves, sandblasting, etc.) or the central strip down the middle of the club face having a width of 1.68 inches (42.67 mm), whichever is greater.
The impact area on driving clubs and fairway woods is defined as the central strip down the middle of the club face having a width of 1.68 inches (42.67 mm).
Note: Grooves and/or punch marks traditionally used to mark the impact area, or any groove which encroaches into the heel or toe portions of the impact area by less than 0.25 inches (6.35 mm) do not have to meet the specifications detailed in Supplement C. However, such markings must not be designed to unduly influence, or have the effect of unduly influencing, the movement of the ball.
For clubs with inserts in the face, the boundary of the impact area is defined by the boundary of the insert, as long as any markings outside the boundary do not encroach the impact area by more than 0.25 inches (6.35 mm) and/or are not designed to influence the movement of the ball. Moreover, the insert itself must extend to at least 0.84 inches (21.34 mm) on either side of the center line of the face and to within at least 0.2 inches (5.08 mm) of the top line and leading edge of the face.
Please note that the above definitions of impact area only apply to new models of clubs manufactured on or after January 1, 2010. For clubs available prior to January 1, 2010, please refer to Supplement A (page 52 of this Guide).
(ii) Impact Area Roughness
When dealing with the surface roughness of a club face (not including putters, see Design of Clubs, Section 5f), the claims made by the manufacturer must be taken into account - especially if there is a claim that the roughness of the face influences the movement of the ball. In the absence of such claims, the ruling would be made purely on the amount of roughness in the impact area. Sandblasting or other treatments of roughness greater than 180 micro inches are not permitted. In addition, for milling, the crest to trough depth must not exceed 0.001 inches (0.025 mm). A reasonable tolerance is allowed for both of these measurements. Non-conforming sandblasting or milling usually feels rough to the touch.
(iii) Impact Area Material
The requirement that the whole of the "impact area" must be of the same material does not apply to clubs made of wood or putters (see Design of Clubs, Section 5f). The reason why it does not apply to wooden headed clubs is to allow the continued use of wooden clubs which have plastic inserts and brass screws in the center of the face. This design was commonly used in persimmon woods, which may still be in use. However, a club face or insert made of a composite material would be considered to be of a single material, and therefore would not be contrary to this rule.
Metal wood club faces which have inserts of different material, not trapezoidal in shape, may be permitted if the height of the insert meets the definition of "impact area" and the width of the insert is the same as the height in at least one point. However, in order to preserve the intent of the "same material" Rule, clubs which have unusually shaped inserts of different material (i.e., other than circular, oval, square or rectangular) are not normally permitted.
If an insert of different material is permitted under the above guideline, the insert would be considered the "impact area" for that club. Therefore, any markings outside that area need not conform to the specifications provided in Appendix II, 5c. However, such markings must not be designed to unduly influence the movement of the ball.
c. Impact Area Markings
Appendix II, 5c provides the specifications for impact area grooves and punch marks.
If a club has grooves and/or punch marks in the impact area they must meet the following specifications:
Grooves must be straight and parallel.
Grooves must have a plain*, symmetrical cross-section and have sides which do not converge (see Figure XI).
The width, spacing and cross-section of the grooves must be consistent throughout the impact area.
The width (W) of each groove must not exceed 0.035 inches (0.9 mm), using the 30 degree method of measurement on file with the USGA.
The distance between edges of adjacent grooves (S) must not be less than three times the width of the grooves, and not less than 0.075 inches (1.905 mm).
The depth of each groove must not exceed 0.020 inches (0.508 mm).
*For clubs other than driving clubs, the cross-sectional area (A) of a groove divided by the groove pitch (W+S) must not exceed 0.0030 square inches per inch (0.0762 mm2/mm) (see Figure XII).
Grooves must not have sharp edges or raised lips.
*For clubs whose loft angle is greater than or equal to 25 degrees, groove edges must have an effective radius which is not less than 0.010 inches (0.254 mm) when measured as shown in Fig. XIII, and not greater than 0.020 inches (0.508 mm). Deviations in effective radius within 0.001 inches (0.0254 mm) are permissible.
(ii) Punch Marks
The maximum dimension of any punch mark must not exceed 0.075 inches (1.905 mm).
The distance between adjacent punch marks (or between punch marks and grooves) must not be less than 0.168 inches (4.27 mm), measured center to center.
The depth of any punch mark must not exceed 0.040 inches (1.02 mm).
*For clubs whose loft angle is greater than or equal to 25 degrees, punch mark edges must have an effective radius which is not less than 0.010 inches (0.254 mm) when measured as shown in Fig. XIII, and not greater than 0.020 inches (0.508 mm). Deviations in effective radius within 0.001 inches (0.0254 mm) are permissible.
Note 1: The groove and punch mark specifications above marked with an asterisk (*) apply only to new models of clubs manufactured on or after January 1, 2010 and any club where the face markings have been purposely altered, for example, by re-grooving. For further information on the status of clubs available before January 1, 2010, please refer to the Informational Club Database at www.usga.org.
Note 2: The Committee may require, in the conditions of competition, that the clubs the player carries must conform to the groove and punch mark specifications above marked with an asterisk (*). This condition is recommended only for competitions involving the highest level of expert player. For further information, refer to Decision 4-1/1 in "Decisions on the Rules of Golf.".
The USGA has adopted this condition for the U.S. Open, U.S. Women's Open, and the U.S. Senior Open Championships conducted after January 1, 2010. By January 1, 2014, the USGA will adopt this condition for all other USGA Championships, as such championships involve expert players.
For competitions conducted after January 1, 2014, the USGA does not recommend adoption of this Condition of Competition unless the competition involves professional-level players and/or players at the highest levels of amateur golf.
If the Committee does not adopt the Condition of Competition, clubs available prior to January 1, 2010, which conformed to the 2008-2009 Rules of Golf may continue to be used in all rounds conducted under the Rules of Golf until at least 2024.
A field test has been developed in order to assist golfers and Officials involved in elite level professional golf in determining the status of clubs available prior to January 1, 2010. Where access to a field test is not available, the USGA has also compiled and published an informational database of irons, fairway woods with lofts of 25 degrees or higher, and hybrids with lofts of 25 degrees or higher, submitted to the USGA and/or The R&A prior to Jan. 1, 2010 and evaluated to determine whether they meet the New Groove Rules. Unlike the List of Conforming Driver Heads, the Database is to be used for reference purposes only. The Database is not to be used in any manner stipulating that clubs must be included in the Database in order to be carried when the Condition of Competition is in effect.
NOTE: The specifications for grooves and punch marks on clubs available before January 1, 2010, are set out in Supplement A along with a complete guide as to the procedure for measuring width, depth and separation when in the field. Additionally, clubs where the face markings have been purposely altered, for example, by re-grooving, must conform to the current groove and punch mark specifications. However, clubs which have only been refurbished back to their original state (e.g., through light sandblasting) may still be eligible for the grace period extended to pre-2010 models.
(iii) Groove/Punch Mark Combinations
If punch marks are used in combination with grooves, the following guidelines apply:
Small punch marks which are in line with a conforming groove, and which would be totally contained within a continuation of the groove, do not have to meet the punch mark to groove specifications. However, if the diameter of such punch marks exceeds the width of the groove, then they must meet the specifications.
When measuring the center to center distance between a punch mark and the end of an in-line groove, the center of the groove is deemed to be half a groove width from the end edge of the groove.
Metal Wood Clubs
Provided the following three conditions are satisfied, the preceding interpretation of the specifications for punch marks in line with a groove may also be granted for metal woods, even if the punch marks would not be totally contained by the continuation of the groove:
There must be no more than three in-line punch marks in the part of the groove that is missing (i.e., in the gap between the ends of the partial grooves);
The combined area of all of the in-line punch marks in any one such gap must not exceed the area of the missing groove; and
The separation of the in-line punch marks from adjacent parallel grooves - measured from center to center - must be at least four times the width of the groove.
The following diagram illustrates each of the above conditions:
d. Decorative Markings
The center of the impact area may be indicated by a design within the boundary of a square whose sides are 0.375 inches (9.53 mm) in length. Such a design must not unduly influence the movement of the ball. Decorative markings are permitted outside the impact area.
The reason for this rule is to permit small, decorative logos in the center of the face or at the side of the "impact area." Non-conforming markings or logos that marginally encroach on the impact area may be permitted, (i.e., by less than .25 inches (6.35 mm)). However, markings outside the ‘impact area' which are designed to unduly influence, or have the effect of unduly influencing the movement of the ball would be contrary to this rule.
e. Non-metallic Club Face Markings
The specifications regarding grooves, punch marks and decorative markings that are applicable to metal faces, or faces made from similarly hard materials, do not apply to faces made from other materials and whose loft angle is 24 degrees or less. However, any markings which could influence the movement of the ball are not permitted on such clubs.
f. Putter Face
The specifications in Appendix II, 5, with regard to roughness, material and markings in the impact area, do not apply to putters. However, any grooves or other permissible markings on a putter face must not have sharp edges or raised lips.
Additionally, if a groove or the grooves on the face of a putter exceed 0.035 inches in width and 0.020 inches in depth, the following guidelines apply:
The width may not exceed 0.06 inches.
The width to spacing ratio must be no less than 1:1.
The depth must be less than the width, and may not exceed 0.04 inches.
Supplement A includes a complete guide regarding the procedure for measuring groove width, depth and separation when in the field.