A beautiful display articulating
the laborious process of forging a carbon steel
blade. Each step in the process is clearly displayed
with a physical representation of the blade and
a nameplate explaining that part of the process.
Parts of the process include: rough forging, rough
shaping, clay covering, quenching, sizing, &
finishing. This display is both aesthetically pleasing
and highly educational.
1. Rough Forging: The blade
is formed by hot forging a billet of super high-carbon
steel. The repeated hammering provides an even dispersion
of carbon throughout the steel for uniform strength
of the finished blade.
2. Rough Shaping: The scale
is removed and the blade is shaped roughly to the
required dimensions. At this stage, the steel is
still in the annealed (soft) state and the blade
is straight.
3. Clay Covering: A special
clay is applied to the blade by hand, using a thin
covering near the edge and a thicker layer over
the rest of the blade. This results in a relatively
quicker cooling of the edge during quenching, producing
a hard edge and softer back.
4. Quenching: This is a
critical part of the operation. The blade, with
its clay covering, is heated to a predetermined
temperature and quenched in a water bath. The shape
and continuity of the hamon (temper line), the sori
(blade curvature), and blade straightness are all
determined by the care and skill exercised in quenching.
5. Sizing: The sori is adjusted
if necessary, to set the point of balance and point
of percussion, and de-scaled. Rough polishing is
carried out to size the blade accurately. The habaki
(blade collar) is fitted.
6. Finishing: Careful final
polishing and fine finish work are carried out on
the various surfaces to define ridgelines and bring
out the beauty of the hamon.
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