If the offensive coach notices an illegal substance on F3's glove, what is the ruling?

The ruling that the glove must be deemed illegal and the player substituted is correct because any illegal substance on a player's equipment, such as a glove, violates the regulations that govern play. The presence of an illegal substance can create an unfair advantage and poses safety risks for players. Therefore, the proper protocol requires that the glove be declared illegal, and the player must be substituted to maintain the integrity of the game.

This ruling is not merely a suggestion; it is an essential part of maintaining fair play and ensuring that all equipment used during the game complies with the established rules. Substituting the player also addresses the immediate issue by removing the non-compliant equipment from the field of play, thereby upholding the standards set forth by the governing body for the sport.