There’s not much difference in knot loft between yesterday’s Yaqi brush (on the right at the right) and the RazoRock 400 I used today, but the feel on the face is worlds apart. As you can see, the two brushes share the same knot shape, so the difference primarily is in the loft. The fibers used feel similar to my hand, though there may be some small difference, but not, I think, enough to account for the marked difference in feel, which I attribute primarily to the difference in loft. Perhaps, though, the knot diameter is a contributing factor.
The RazoRock 400 has a 24mm knot with a 57mm loft.
The Yaqi Cola brush has a 22mm knot with a 50mm loft.
But maybe the fibers do contribute to the difference in feel: the Yaqi Soft Cashmere synthetic also has a 22mm knot with a 50mm loft, but I don’t experience with it the dissatisfaction I feel toward the Cola brush.
I did my usual stepwise lather load, starting with a brush almost dry (“almost dry” conveys a more accurate impression than “barely damp”), I add very small amounts of water as I brush the puck, and when the brush is loaded with soap/proto-lather, I move to my face and work up the lather there, adding more water to increase lather volume (and water content).
The shave itself was a pleasure, thanks to Propaganda’s wonderful fragrance and the smooth and efficient action of the Merkur 37G. Three passes left a BBS result, and a splash of Floïd with a couple of squirts of Hydrating Gel finished the shave on a somewhat chilly note — Floïd is well mentholated. Sometimes Floïd’s menthol level seems quite mild, but on a cold winter morning it seems much more intense. Context plays a big role in our perceptions.