Tan Sao (Dispersing Hand)
Tan Sau or "dispersing hand" is an intercepting technique designed to change or disperse the direction of an opponent's attack, as the name implies. Similar to Fook Sau, the Tan Sau makes contact with the forearm. However, instead of the fleshy side, the Tan Sau utilizes the bony side of the forearm. The Tan Sau is used as an offensively oriented defensive technique. This means that the Tan Sau can be used to defend against strikes but its main purpose is to create an opportunity for the user to strike.
The key points to the proper execution of the Tan Sau are: Elbow is bent, facing downward, and in the same vertical plane as the hand and wrist. Hand is facing upward and engaged. Fingers are straight and slightly engaged. The thumb is bent and tucked into the palm of the hand. Palm is open; a small object should be able to sit on the palm. Shoulder is relaxed and not engaged.
At a first glance, the Tan Sau looks like a blocking technique that uses the forearm. However, the Tan Sau is actually uses to actively change the direction of an opponent's energy and create an opening for the user. The Tan Sau has forward energy the forcibly deflects the opponent's energy because the Tan Sau is moving forward. By utilizing the bony side of the forearm, the Tan Sau allows the user to slide stealthily closer to the opponent and pry open the opponent's defense.
Additionally, the Tan Sau provokes natural reactions from the opponent that can compound with the user's own attack. For example, if an opponent's defense is pried open by a Tan Sau pushing the arm outward, the opponent's natural reaction is to pull the arm inward. A Wing Chun user can actually use this natural reaction as a springboard for their attack.