Appendix1

THE BALL
a. The ball shall have a uniform outer surface consisting of a fabric cover and shall be white or yellow in colour. If there are any seams they shall be stitchless.
b. The ball shall conform to these requirements and have a weight (mass) of more than 1.975 ounces (56.0 grams) and less than 2.095 ounces (59.4 grams).
c. More than one type of ball is specified. Each ball shall have a bound of more than 53 inches (134.62 cm) and less than 58 inches (147.32 cm) when dropped 100 inches (254.00 cm) upon a flat, rigid surface e.g. concrete. Ball Type 1 (fast speed) shall have a forward deformation of more than .195 inches (.495 cm) and less than .235 inches (.597 cm) and return deformation of more than .265 inches (.673 cm) and less than .360 inches (.914 cm) at 18 lb (8.165 kg) load. Ball Types 2 (medium speed) and 3 (slow speed) shall have a forward deformation of more than .220 inches (.559 cm) and less than .290 inches (.737 cm) and return deformation of more than .315 inches (.800 cm) and less than .425 inches (1.080 cm) at 18 lb (8.165 kg) load. The two deformation figures shall be the averages of three individual readings along three axes of the ball and no two individual readings shall differ by more than .030 inches (.076 cm) in each case.
d. For play above 4,000 feet (1219 m) in altitude above sea level, two additional types of ball may be used.
i. The first type is identical to Ball Type 2 (medium speed) as defined above except that the ball shall have a bound of more than 48 inches (121.92 cm) and less than 53 inches (134.62 cm) and shall have an internal pressure that is greater than the external pressure. This type of tennis ball is commonly known as a pressurised ball.
ii. The second type is identical to Ball Type 2 (medium speed) as defined above except that the ball shall have an internal pressure that is approximately equal to the external pressure and have been acclimatised for 60 days or more at the altitude of the specific tournament. This type of tennis ball is commonly known as a zero-pressure or non-pressurised ball.
The third type of ball which is recommended for use for play on any court surface type above 4,000 feet (1219 m) in altitude is the Ball Type 3 (slow speed), as defined above.
e. All tests for bound, size and deformation shall be made in accordance with the regulations below.
Case 1: Which ball type should be used on which court surface?
Decision: 3 different types of balls are approved for play under the Rules of Tennis, however:
a. Ball Type 1 (fast speed) is intended for play on slow pace court surfaces
b. Ball Type 2 (medium speed) is intended for play on medium/medium-fast pace court surfaces
c. Ball Type 3 (slow speed) is intended for play on fast pace court surfaces
REGULATIONS FOR MAKING TESTS
i. Unless otherwise specified all tests shall be made at a temperature of approximately 68o Fahrenheit (20o Celsius) and a relative humidity of approximately 60%. All balls shall be removed from their container and kept at the recognised temperature and humidity for 24 hours prior to testing, and shall be at that temperature and humidity when the test is commenced.
ii. Unless otherwise specified the limits are for a test conducted in an atmospheric pressure resulting in a barometric reading of approximately 30 inches (76 cm).
iii. Other standards may be fixed for localities where the average temperature, humidity or average barometric pressure at which the game is being played differ materially from 68o Fahrenheit (20o Celsius), 60% and 30 inches (76 cm) respectively.
Applications for such adjusted standards may be made by any National Association to the International Tennis Federation and, if approved, shall be adopted for such localities.
iv. In all tests for diameter, a ring gauge shall be used consisting of a metal plate, preferably non-corrosive, of a uniform thickness of one-eighth of an inch (.318 cm). In the case of Ball Type 1 (fast speed) and Ball Type 2 (medium speed) balls there shall be two circular openings in the plate measuring 2.575 inches (6.541 cm) and 2.700 inches (6.858 cm) in diameter respectively. In the case of Ball Type 3 (slow speed) balls there shall be two circular openings in the plate measuring 2.750 inches (6.985 cm) and 2.875 inches (7.302 cm) in diameter respectively. The inner surface of the gauge shall have a convex profile with a radius of one-sixteenth of an inch (.159 cm). The ball shall not drop through the smaller opening by its own weight and shall drop through the larger opening by its own weight.
v. In all tests for deformation conducted under Rule 3, the machine designed by Percy Herbert Stevens and patented in Great Britain under Patent No. 230250, together with the subsequent additions and improvements thereto, including the modifications required to take return deformations, shall be employed. Other machines may be specified which give equivalent readings to the Stevens machine and these may be used for testing ball deformation where such machines have been given approval by the International Tennis Federation.
vi. The procedure for carrying out tests is as follows and should take place in the order specified:
a. Pre-compression before any ball is tested it shall be steadily compressed by approximately one inch (2.54 cm) on each of three diameters at right angles to one another in succession; this process to be carried out three times (nine compressions in all). All tests are to be completed within two hours of precompression.
b. Weight (mass) test (as above).
c. Size test (as in paragraph iv above).
d. Deformation test the ball is placed in position on the modified Stevens machine so that neither platen of the machine is in contact with the cover seam. The contact weight is applied, the pointer and the mark brought level, and the dials set to zero. The test weight is placed on the beam in a position that is equivalent to a load of 18 lb (8.165 kg) on the ball, after which the wheel is turned at a uniform speed such that five seconds elapse from the instant the beam leaves its seat until the pointer is brought level with the mark. When turning ceases the reading is recorded (forward deformation). The wheel is turned again until figure ten is reached on the scale (1 inch (2.54 cm) deformation). The wheel is then rotated in the opposite direction at a uniform speed (thus releasing pressure) until the beam pointer again coincides with the mark. After waiting ten seconds, the pointer is adjusted to the mark if necessary. The reading is then recorded (return deformation). This procedure is repeated on each ball across the two diameters at right angles to the initial position and to each other.
e. Bound test (as above) measurements are to be taken from the concrete base to the bottom of the ball.
CLASSIFICATION OF COURT SURFACE PACE
The ITF test method used for determining the pace of a court surface is test method ITF CS 01/01 (ITF Surface Pace Rating) as described in the ITF publication entitled An initial ITF study on performance standards for tennis court surfaces.
Court surfaces which are found to have an ITF Surface Pace Rating of between 0 and 35 shall be classified as being Category 1 (slow pace). Examples of court surface types which conform to this classification will include most clay courts and other types of unbound mineral surface.
Court surfaces which are found to have an ITF Surface Pace Rating of between 30 and 45 shall be classified as being Category 2 (medium/medium-fast pace). Examples of court surface types which conform to this classification will include most hardcourts with various acrylic type coatings plus some textile surfaces.
Court surfaces which are found to have an ITF Surface Pace Rating of over 40 shall be classified as being Category 3 (fast pace). Examples of court surface types which conform to this classification will include most natural grass, artificial turf and some textile surfaces.
Note: The proposed overlap in ITF Surface Pace Rating values for the above categories is to allow some latitude in ball selection.