The traditional sharpening steel does not sharpen; it maintains the edge by unfolding it. This straightened edge is still weak and quickly folds again. Eventually, the edge breaks off or folds so tightly that it can't be straightened with a steel and must be reshaped. Using a steel requires significant skill and practice. To be effective at all, the steel must be used after every 10 to 50 cuts, before the edge folds over too much to straighten. True sharpening removes the old weak edge and reshapes a new stronger edge.