What do you guys think about a shaving brush with a knot that can change diameter by telescoping out of the brush? One day it can be close and tight and with a twist can spread out to become longer and more soft?
I am not sure what you are proposing. A brush were the knot can be compressed (when you put a rubber band at the base of the knot to increase backbone), or adjusting the loft by telescoping the knot up. There are brushes where you can adjust the loft, but I have never tried one.