[TheForge] Samurai program

[Jerry Smith]

To sum this up, yes it is true. I have put Terra cotta
clay on the spine of a long knife before heat treating
it. The spine doesn't heat treat the same as the
cutting edge, so it is softer and makes the whole
sword more forgiving.

Let the clay dry some before HTing, the water content
of the clay will give you some surprises if you don't.

Jerry
--- schade at acegroup.cc wrote:

> 
> On Oct 6, 2007, at 11:36 AM, Bob Smolen wrote:
> 
> > I believe PBS is going to show a program on
> Samurai swords this coming 
> > Tues. at 7:00. Check your listings if you are
> interested.
> > Bob
> > _______________________________________________
> >
> 
> If you go to the Nova site there is an interactive
> slide show
> showing some of the highlights of the show. In one
> segment they
> say that the curve in the finished blade is made by
> quenching
> (clipped/pasted below). I am not a knifemaker or
> student of
> damascus/samurai swords/patternwelding/etc but I
> have never
> heard this before.
> 
> Is it true?
> 
> Looks like a good show.
> 
> Bob
> 
> http://www.pbs.org/wgbh/nova/samurai/sword.html
> 
> launch interactive
> 
> "Curving the blade
> Next, the smith pulls the katana from the fire and
> plunges it into a 
> trough of water in a rapid cool-down process called
> "quenching." 
> Because the sword's back edge and inner core contain
> very little 
> carbon, they can contract more freely than the
> high-carbon steel at the 
> front edge of the blade. The difference in both the
> degree and speed of 
> contraction between the two forms of tamahagane
> causes the sword to 
> bend, creating the distinctive curve. This is a
> tricky stage, in which 
> as many as one in three swords is lost."
> 
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