D. Ajay
Both the sides of a racket were same in colour in the eight decade of the nineteen centaury and the then players were using different types of rubber on both the side. So it was very tough for the opponent player to guess the quality of the coming stroke and return the ball within the very short time. This was ultimately reducing the continuity of play which is not at all the motto of International Table tennis Federation.
Different types of rubbers are producing different types of strokes. When a category of rubber produces spin, other category of rubber absorbs spin. Like this rubbers are available for fast stroke and anti-spin stroke etc.
It was allowed to use one side rubber of a racket for imparting spin with a combination of another side for imparting no spin or one side for absorbing spin & another side for imparting speed during that period. More over players were rotating their racket from fore hand to back hand & vice versa in a rally for scoring a point in a game by tricking the opponent. This was resulted very less number of rallies for a point which ultimately was making the event charm less.
So the event cultivators decided that the receiver should get the chance to think about the coming stroke for making it return. As the result, the ITTF changed the rule regarding the rubbers of a racket like this:
a) Rubbers of both side of a racket must be of different colour.
b) The colour of both the side must be red & black.
c) If one side of a racket is not used by the player, it must be coloured with the other colour of the used colour.
d) All the players will be allowed to check the rackets of the opponent of the match just before the starting of the game of a match.
These are all only for providing the chance to the opponent to recognize the types of coming stroke made by the opponent.