
Those include: 1) hair type and quality (e.g., softness, resilience), 2) base diameter (measured at the top of the glue plug), 3) volume density at its base, 4) shape, 5) depth of set, 6) diameter of the socket into which the knot has been set, 7) loft, and 8) free loft.

Several variables can affect the appearance, feel, and performance of a knot. These two specifications, however, do not adequately serve prediction of how a brush will feel or perform in use. Loft is the most common and often the only measurement given in description of a brush’s knot besides its base diameter. This brush’s loft, calculated by subtracting handle height from overall brush height, is 52.25 mm. Loft refers to the vertical distance from a) the top of a handle where the knot is inserted into the socket (often referred to as the knot hole) to b) the knot’s crown or peak, which, assuming the knot has a dome-shaped top (or canopy), will be at or very close to its center. The overall height of this brush is 111.65 mm, with the handle contributing 59.4 mm. Its knot was installed by Lee Sabini in England, who sets knots a little differently than we do, but the difference is not important for purposes of this discussion.

The photo below shows a cutaway section of a Paladin™ Chief™ shaving brush.

There are basically two parts to a badger-hair shaving brush: a handle and a knot.
