I've heard of others using zip ties. When I first experimented I did a thread whip, like the whip on the end of laid rope. That worked but was not very permanent. Setting the brush deeper had a different and IMO better effect.
Yup, I did use a West Country Whipping to temporarily adjust the loft on a brush. It showed I was going in the right direction and worked when I reset the loft to what I had it choked to.