Bong Sau is a very, very important movement in Wing Chun. It's one of the three seed techniques along Tan sau and Fuuk Sau, and it's also one of the most misunderstood movements in wing chun. Of course according to whatever lineage or whatever style of Wing Chun you practice, everybody teaches and preaches a different use for the Bong Sau. The version I'm going to teach you obviously comes from the system of Wing Chun that we teach here at our school. And I am going to explain a little bit how and why we use it and also how we don't use, which is maybe a little bit different form some of the other styles.
First of all, you have to understand, bong sau is not a fixed position. Bong Sau is not not something you do to block a punch. It's not something you do to stop. Bong Sau is actually just a reaction. Okay, that's why they say in Chinese, they say "Bong Sau, Fa Sau," which means Bong Sau is not really a hand technique. It's actually just a reaction, and all the models that support how we use Bong Sau are based on reaction, they're not based on blocking. So, we have a saying in Wing Chun - When you press the head, the tail raises. This actually teaches you how Bong Sau is formed.
If I send my hands forward in the middle of a fight and I run into my opponent's arm, and let's say that he's got a very tight low elbow structure here, and I'm not able to go through. When he continues towards me, he's, in essence, pressing the head of my arm, which is the front part. And the reaction from me to do is to turn up the end and to do what we call Bong Sau. Now this is totally based on the pressure that I get from him. It's not that he comes with a punch and I used Bong Sau to block as you see in a lot of other styles, this would be totally unnecessary. If he fires a punch towards my head, I can just go in and hit him. There's no need for me to Bong Sau and block and do a big complicated defense. I'm only going to Bong Sau if he actually presses down they arm and forces me to turn too, so it's very passive, it's based on his force, and that's what we mean by 'it's not a hand technique.' It's not something you choose to do, it's something your opponent actually forces you to do.
This is the main idea behind Bong Sau. And it's very important that you train it correctly. When you start learning single arm Chi Sau, when your partner gives you a punch, he needs to give a low elbow punch, so that it bends your arm like this. If he were to give me a punch to the face, my reaction, would actually be to go in and do an indoor punch, because of Bong Sau is completely unsuitable for the defending a face punch. This actually just ends up being a ramp to your face. If the punch was common this high, it's much more suitable to go in and use a wedge like this. The Bong Sau is only done, literally, when he presses the arm like this here. So my arm's very elastic as opposed to being rigid. And it'll only be in this form for a second. When he comes in a punches me, I don't hold and pose this Bong Sau for everybody to see, it would actually just be part of a quicker and more complex reaction, as opposed to it being something that I pose and stop. And this Bong Sau.