During the folding process, most of the impurities are removed from the steel, continuously refining the steel while forging. By the end of forging, the steel produced was among the purest steel-alloys of the ancient world. Due to the continuous heating the steel tends to decarburize, so a good quantity of carbon is either extracted from the steel as carbon dioxide or redistributed more evenly through diffusion, leaving a nearly eutectoid composition (containing 0.77 to 0.8% carbon).[23][24] The edge-steel itself will generally end up with a composition that ranges from eutectoid to slightly hypoeutectoid (containing a carbon content under the eutectoid composition), giving enough hardenability without sacrificing ductility[25] The skin-steel generally has slightly less carbon, often in the range of 0.5%.