"In regards to using corrosion to date a blade, it might be worth mentioning,
that it is the accepted method of dating Japanese blades through the
examination of the corrosion on the tang. I think a lot of study as been put
into this over the years and one can start seeing trends in the depth of
corrosion, color of corrosion, etc. and match this to dated tangs to get an
"eye" for dating an unsigned blade. Barring new technology that can
somehow date the metal of the blade, studying a blades tang seems to be an
accepted method of dating. Thoughts?"
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The type of rust, extent of rust and color of rust is
used as an aid in dating Japanese swords. However, everyone
realizes that it can be "faked". In Nihonto circles it is
bad to ever clean the tang of a sword since it is used
in dating. The basic guidelines (just that - guidelines)
are in order of recent to oldest: red rust, brown rust,
rough black rust, smooth black rust. Again though I must
mention, as has been said, it is just one aspect of dating
the sword and is not considered absolute by any means.
Other things considered are shape, prominence of hada (grain
in the folding process), style of hamon (temperline), among
others. None of these are absolute and any or all can be
replicated by modern smiths. That why we have shinsa
(judging) by a group of Japanese experts and even then
errors are sometimes made.
Interesting thread. I wish there was a simple, fool proof
method of dating blades of any culture. It would sure
simplify things. How about all the "bronze age" fakes on
the market?
Rich S
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Richard Stein, PhD
alchemyst@yahoo.com
The Japanese Sword Index
http://www.geocities.com/alchemyst/nihonto.htm
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