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Originally Posted by Jim McDougall
Ed and Philip, one of the greatest conundrums for me in understanding, from metallurgical perspective, can blades be stamped with these kinds of marks after they are finished?
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Whether a blade can be stamped, engraved, or chiseled post-heat treat depends on the hardness achieved, and also the area of the blade affected by said process. The latter point is important because in various traditions, blades were differentially heat treated, the zone along the edge(s) becoming quite hard whereas the back or center remaining fairly soft. People automatically associate this technique with the Far East, but it has been observed on Western blades from a variety of sources, from hand-forged Bowie knives of the early 19th cent. to Italian rapier blades from two or three centuries earlier.
As an arms restorer whose practice involves a lot of blade polish, I have been able to observe a lot of this empirically. Since Japanese blade quenching involves only the edge zone,
horimono can be carved on the relatively soft, burnished area above the
shinogi and historically, many blades were decorated in this way post-manufacture. I have worked on Philippine blades with glass-hard edges, but with deep dents further back where some idiot tried to straighten a bend by whacking it with a hammer. If you can make such well-defined dents with a hammerhead, then a marking stamp can make quite an impression as well. Hit the edge with that hammer and it would likely chip or crack like the rim of a teacup.
Wootz is surprisingly variable. Many Persian and Ottoman blades with beautiful patterns are actually so soft that they can be shaped with a file, whereas a lot of Indian ones with low-contrast grainy structure are very hard. And yes, I've had to deal with some that have deep scars from percussion tools just as I mentioned above. And another thing -- a lot of Ottoman blades were subsequently decorated with aftermarket gold overlay, the steel would have to be deeply scored with a graver to crosshatch the surface, and annealing and re-tempering a wootz blade invites all sorts of problems especially if you want to preserve the watering.
The point that I'm trying to make is that you can't really generalize. These old blades exhibit a range of physical characteristics so something that may apply to some cases would not necessarily be applicable to all.