In this work, we assessed the potential of Cel6D, a recently reported exocellulase from Paenibacillus barcinonensis, as a biorefining agent for flax pulp. Pulp fibers were treated with this enzyme, Cel9B (an endocellulase previously shown to possess biorefining action) and the two in combination. Samples of biorefined flax pulp were mechanically refined to obtain handsheets. All three biorefining treatments decreased air permeance in the handsheets. Cel9B increased tensile index and folding endurance, and the Cel6D¿-¿Cel9B combination increased tensile index and burst index but also resulted in markedly decreased tear index and folding endurance. On the other hand, Cel6D increased tensile index and burst index; also, more importantly, it increased tear resistance, albeit slightly, relative to the other two treatments. The results of this work can be useful to understand the differential effects of exocellulases and endocellulases as biorefining tools and open up new avenues for exploring their use in other biotechnological applications