We prove that the proof system CL, even without restarts, is stronger than all proper natural refinements of RES. We do this by first introducing a way of extending any CNF formula based on a given RES proof of it. We then show that if a formula F f (n)-separates RES from a natural refinement S, its extension f (n)-separates CL from S. The existence of such an F is guaranteed for all f (n)-proper natural refinements by definition.