What is the finish on Council Tool Sport Finish axes?

[leozinho]

Like this one.

I guess it forge scale, then a smoother dark section, and finally a bare metal convex edge.

I'm particular curious about the middle, smooth dark section. How is that done?

Thanks.

 

[FortyTwoBlades]

After forging the heads get the scale removed in a tumbler, then before tempering they cover the heads in oil, which produces the darkened appearance.