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A
good text from Richard Furrer, this text had been published in
the Crucible forum
Wootz
is an ancient steel most likely developed in India
around 200 A.D.. Some say it goes back further, but there
is limited research in this area. The material is a combination
of iron, carbon and glass placed in a clay crucible and fired
till it goes molten (thought there are a few other manufacturing
methods in history). The iron will gather carbon from the charcoal
and become steel and the glass will melt and act as a flux which
will chemically bond with the impurities in the iron and remove
them.
The molten steel is allowed to cool and the resulting solidified
ingot is then removed from the crucible ( the crucible is broken).
The ingot, ranging from 1/2 to four pounds, is then forged into
a tool -- usually a blade. The ingot is difficult to forge and
is often broken in the process which further adds to the mystery
of the steel.
The steel itself usually has between 1 and 2% carbon, though there
are a few examples of lower carbon contents in history. The main
appeal is that the finished blade has a surface pattern. I call
this pattern "salt and pepper" in appearance, but the Persian
poets have likened it to wind rippling across a pond or tracks
of ants. Basically the pattern results from the constituent elements
nucleating out into two distinct formations -- carbides and pearlite.
The carbides are white and the pearlite matrix is darker. Other
structures can be formed, but historically these are the two main
ones. The overall effect is that of "diamonds in pudding" (my
quote) where the diamonds (carbides) do the cutting and the pudding
(pearlite) acts as the matrix which supports the carbides. What
makes this interesting is that the carbides form groupings which
are visible with the naked eye -- much like pictures in the old
newspapers. The photos in the newspaper are actually made up of
tiny dots (like the individual carbides), but since they can be
grouped together closely they appear to be continuous lines and
shapes. This is why we can see the carbides in the wootz -- they
are groupings of the tiny individual carbides into alternating
"cluster sheets" of carbides and pearlite. These sheets can be
further manipulated to form gross patterns like the famed "kirk
narduban" or Muhammad's ladder.
What
this means in function is that the carbides wear very slowly and
the matrix wears faster so there is a definite saw tooth action.
The wootz will chew its way through material. It therefore is
very good for cutting flesh (its intended target), but not so
good in cutting other things. It would make a poor wood planer
blade for instance because it would leave tiny grooves in the
wood rather than take a clean shaving. Very few people understand
what the best uses for this material is and therefore they think
that all of the legends are true and wish to think of wootz as
the best all around cutting tool.
I will say that it seems to cut meat better than anything I have
tried before and when you consider the historical use for the
material I believe that the ancients found the same to be true.
It is not a "perfect material", but it is still very mysterious.
I apologies to those who wish to believe all the wonderful myths
surrounding the material. I struggled for years with these myths
and separating fact from fiction is one of my personal struggles
with steel.
I began my study of wootz over a decade ago. What began with a
few simple questions has grown over the years into several hundred
very specific questions and every new discovery leads to another
layer of detail requiring further investigation. Its is a wonderful
challenge and my respect for the ancient craftsmen has grown with
every new ingot I make.
Richard Furrer
Sturgeon Bay, WI
In
Russia, Wootz Steel is called Bulat, today Serguey
Lounyov pursue the work of his ancestors.
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