Mainspring stretching for cleaning & oiling

The following set of photos shows how I hold and stretch out a typical mainspring for cleaning and oiling. I am holding the camera in my right hand.. just as I would be holding steel wool, rags, etc in my right hand while cleaning or oiling the spring. The hook screwed in the edge of my bench is L-shaped and should be stout enough and screwed in far enough to allow some force to be applied to it from the stretching. I make no attempt to stretch the spring any further than is shown in the last picture. With my right hand I work on the straight portion while holding it taut with my left hand.