TV Program Description
Original PBS Broadcast Date: October 9, 2007
English archers had their longbows, Old West
sheriffs had their six-guns, but samurai warriors had the most fearsome weapon
of all: the razor-sharp, unsurpassed technology of the katana, or samurai sword. In this program, NOVA probes
the centuries-old secrets that went into forging what many consider the perfect
blade.
The beauty and lethality of the curved steel blade
became identified with the distinctive culture of those who wielded it so
expertly: the samurai warriors of medieval Japan, celebrated in countless
Japanese woodcuts, prints, and films. Fifteen traditional Japanese craftsmen
spent nearly six months creating the sword that NOVA follows through
production, from smelting the ore to forging the steel to sharpening the blade
to a keen edge, capable of slicing through a row of warriors at one
swoop—although NOVA does not put the super-weapon to this ultimate test.
(See a slide show of the process.)
Not that samurai sword fighting has died out—far
from it. The program also traces the schooling of a modern-day devotee of
samurai combat: Midori Tanaka, a receptionist for a Japanese electronics firm
by day and a blade buff by night. For Tanaka it's a family tradition, since her
father, Fumon Tanaka, is a grand master swordsman.
Father and daughter show their mutual respect with
a breathtaking test of skill. Midori draws a bow, aiming an arrow directly at
her father's heart. His only protection is his sword. When she releases the
string, he slices the speeding arrow in half, inches from its target.
Japanese sword-making developed centuries ago,
before electron microscopy, mass spectrometry, and other tools of modern
materials analysis enabled scientists to understand exactly why the swords are
as good as they are. Professor Michael Notis of Lehigh University, an expert on
samurai swords, sheds light on the principles that underlie the weapons'
strength, resilience, beauty, and distinctive shape.
(See an interview on metal's properties with Notis's colleague Rick Vinci.)
For example, during smelting, iron-ore sand is
heated with charcoal, which provides a source of carbon that alloys with the
iron to create steel. Ancient craftsmen deliberately stopped just short of a
uniform liquid state for the white-hot steel, which resulted in a product with
varying amounts of carbon throughout. The harder high-carbon steel was forged
into the sword's edge, which had to be hard and sharp, while the more resilient
low-carbon steel was used as the core of the weapon to produce a blade
resistant to breaking during combat.
This sandwich of two different types of steel
contracted at different rates during rapid cooling, or quenching, which caused
the blade to warp lengthwise, giving it its distinctive curve that proved so
deadly when wielded in a slashing arc. "The unique aspect of the Japanese sword
is that the craftsmen were able to put the right materials in the right place
to get optimum properties for the entire object," Notis tells NOVA.
Without access to the insights of modern science,
Japanese craftsmen a millennium ago worked out an exacting method that is still
followed by a devoted few and that produces the Stradivarius of swords.
Program Transcript
Program Credits
