The color identifies the rubber, not the spin
A table-tennis paddle, usually called a racket, can have a different rubber surface on each side. One side might use smooth rubber that grips the ball; the other might use rubber with short pimples, or a different sponge and rubber combination. Those surfaces can send back balls with different spin and speed.
The colors do not create those differences. They make the sides easy to tell apart. If a player turns the racket in the hand before a shot, the opponent can see which surface is facing the ball and adjust the return. Without contrasting colors, a player could switch surfaces while making the racket’s orientation much harder to track.
A visible clue in a fast exchange
Spin is difficult to read from the ball alone. A shot with topspin tends to kick forward after bouncing; backspin tends to slow or dip. The receiving player has to judge the rotation quickly and angle the racket accordingly. Knowing which rubber made contact adds another clue—especially when a player uses one surface to produce heavy spin and the other to disrupt it.
The colors are therefore a small piece of game design: they preserve the advantage of choosing different rubbers while keeping that choice visible to an opponent. In a rally, the brief flash of red or black can help explain why a seemingly similar stroke makes the ball behave very differently.
