A ball on the putting green may be cleaned when lifted under
Rule 16-1b. Elsewhere, a ball may be cleaned when lifted
except when it has been lifted:
a. To determine if it is unfit for play (Rule 5-3);
b. For identification (Rule 12-2), in which case it may be
cleaned only to the extent necessary for identification; or
c. Because it is assisting or interfering with play (Rule 22).
If a player cleans his ball during play of a hole except as
provided in this Rule, he incurs a penalty of one stroke and the
ball, if lifted, must be replaced.
If a player who is required to replace a ball fails to do so, he
incurs the penalty for breach of Rule 20-3a, but there is no
additional penalty under Rule 21.