Those are interesting links, thank you. Perhaps you can clear up some confusion on my part - I have read speculation that some Simpson brushes have a glue bump. Given that Simpson turn their handles, then apply a layer of glue into the base of the hole, and finally insert the knot, which is tied with string and which has no fixed glue plug, then I wonder how any domed glue bump especially above the top of the handle is possible. It seems particularly unlikely given the depth at which Simpson set their knots in their handles, sometimes as much as a third of the handle height. Surely Simpson brushes cannot have a glue bump or do I misunderstand? Thank you.Maybe, from Paladin:
BRUSHOLOGY: ANATOMY AND NOMENCLATURE
Brushology: On Glue and Glue Bumps
You could just pinch the knot were it meets the handle, if there's a glue bump the center of the knot is unforgiving, hard. It's not a bad thing unless it detracts from the performance of the brush.