Once the umpire detects a ball with foreign substance he should call an illegal pitch. (Rule 6-6 effect a-b-1 FP.) (Rule 6-5 effect a-b SP) In a Canadian Championship the pitcher is warned one time for the infraction before an illegal pitch is called.

In FP If there is continued use of foreign substance on the ball call an illegal pitch for each infraction and immediately inform the coach if another ball has foreign substance on it, the pitcher is ejected (Rule 6-7 a-b 2)

In SP you do not have to warn the manager/coach prior to ejecting the pitcher for continued violation of foreign substance on the ball (Rule 6-5 Effect a-b)