I have an unbleached Zenith boar, the backbone or stiffness of the brush is as hard as a wire brush, it takes ages to break-in, as a matter of fact I don't think it ever breaks-in. Perhaps you may have a better luck. After trying all the techniques to accelerate the break-in period I managed to use mine. But it was very cheap.
@Nisse in the "Show Your Boars" thread said the unbleached one was a bit like a slightly softer Omega.
I'll be intrigued to whether my unbleached one will be a wire brush or the other one!