Disclosed is a refiner filling piece for a refiner having a rotor that rotates about an axis of rotation and cooperates with a stator to mechanically treat a pulp containing cellulosic fibers. The refiner filling piece is mountable to the rotor or the stator. The refiner filling piece comprises a base and a plurality of spaced-apart refiner bars, each refiner bar being defined by a bar length and a bar height. At least some of the refiner bars have a surface coated with a stepped coating. The surface having the stepped coating may be the leading surface of the refiner bar.

Disclosed is a refiner filling piece for a refiner having a rotor that rotates about an axis of rotation and cooperates with a stator to mechanically treat a pulp containing cellulosic fibers. The refiner filling piece is mountable to the rotor or the stator. The refiner filling piece comprises a base and a plurality of spaced-apart refiner bars, each refiner bar being defined by a bar length and a bar height. At least some of the refiner bars have a surface coated with a stepped coating. The surface having the stepped coating may be the leading surface of the refiner bar.