That has to do with the martinsetic steel being abraided away. The old tamahange steel was very shallow hardening with not much martinsite on the blade after quenching. The initial grind would remove much of it, not leaving much for subsiquent sharpenings and polishings. That is probably the one place where a hamon is funtional; when it's gone so is all the hard steel.
Doug Lester
__________________
If you're not making mistakes then you're not trying hard enough
|