According to ITTF rules, both sides of the racket must be black and red. This is because there are too many kinds of rubber, including granular rubber (positive rubber, long rubber, raw rubber) and reverse rubber (flat rubber), each of which can make the ball rotate differently. And if you don't distinguish them, they are all black, then you can't distinguish what kind of rubber your opponent uses in the game, and you can't distinguish the opponent's ball path and rotation. In this way, the opposing sides can know what kind of rubber they use when hitting the ball through color discrimination, so as to achieve the purpose of fair play.

Common rubber features are as follows:

Positive glue is a kind of granular glue, which has a high degree of vulcanization and large particles, and the height is between 0.8-1.0 mm. Positive glue particles are hard and lack of viscosity, and are usually used in conjunction with soft sponges. In order to increase the spinning ability of positive glue, all brands have made tiny patterns on the top of positive glue particles. Positive glue returns the ball quickly and can make a certain rotation, which is suitable for fast break players at the table. Close-to-the-table straight-and-glue fast-break play is China's traditional play.

Raw rubber is a kind of positive rubber with a low degree of vulcanization. Usually, the particles are small, with a height of 0.8-1.0 mm. The raw rubber particles are soft and have poor ability to rotate. It is usually used with a slightly thinner sponge. Raw rubber hits the ball quickly and the return ball sinks, which can produce a certain "anti-rotation" effect. It is often used in backhand by players who combine fast break with curling or chopping.

Long rubber is a kind of soft particle rubber, and its height is1.5-1.7 mm. The return speed of long rubber ball is slow, but it can rotate completely contrary to that of conventional rubber ball. When cutting the curve ball, you can rely on the opponent's strength and rotation to produce an abnormal return ball. It is usually used by eccentric athletes or as a backhand eraser for chippers.

Reverse glue is the most commonly used kind of rubber, usually used with hard and thick sponge. Anti-glue has a strong impact force and strong rotation. Players choose it for all types of games.

Arc-proof glue is a kind of thick, hard, elastic and somewhat astringent glue, which is usually used in conjunction with sponges with loose structure. It has a strong buffering effect and can effectively weaken the role of the powerful spinning ball. It is often used to control the opponent's loop ball, but the power and rotation of returning the ball are not strong.