I'm sure many of us musicians have heard the 'don't force the sound out', 'stop the tension' teacher quotes. Yet will simply relaxing produce that clear, sustained, non-flautando sound? Perhaps. For me, that only does a portion of the trick. Because alas! Sometimes we relax too much and end up playing French music. The other half consists of my own awareness towards my natural weight, how I'm catching the string and my bow control. All basic stuff that we often forget - too easily.
Alright let's expand on these ideas.
Quite often I remember bow control when I observe great players performing live. (Usually my senpais - colleagues /classmates / older 'brother' and 'sister' in Japanese) I notice when they begin playing or stop a note they don't just sloppily take the bow off the string. instead they know exactly which part of the bow they are using and place the bow purposefully. While it hits the string gently, you'll find it's gripped on like magnet - it attracts naturally, no need for added pressure. When they draw the bow across, the grip is still there, felt by the input of your natural body weight.
To be honest, it's difficult to put the feeling into words as you really need to be aware of your own body and 'feel' it.
Nevertheless I hope you get what I mean sometime during your next practice session!