Abstract: A retractable debarking block for a debarker having an enclosure to receive logs for debarking in order to vary the aggressiveness of the debarking process. The block member has a debarking surface with projecting teeth and is positionable within the enclosure of the debarker to be movable between a retracted position in which the debarking surface does not contact logs in the enclosure and an exposed position in which the debarking surface is exposed to engage logs. The block member is fittable into a rotor or drum type debarker. An actuator is provided to move the debarking surface between the retracted and exposed positions. The actuator is adapted to permit automatic movement of the debarking surface toward the retracted position if the force exerted by the logs exceeds a pre-set limit to prevent damage to the blocks and the logs. Preferably, the actuator is an airbag or telescoping cylinder operable over a range of pressures to permit adjustment of the pre-set limit.