Bob Hoover wrote:
On Mar 15, 8:41 pm, Brian Whatcott wrote:

I felt good - just reading that old recipe. Thank you
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Dear Brian,

I don't know how true it is ( ie, the infusion of trace elements in
leather charcoal ) but I've heard it from more than one machinist
whose advice I feel I can trust. The only quantified test I know of
[done with a 'gas chromatograph'??] showed that different leathers did
in fact show different amounts of things such as chromium and
vanadium. Ditto for bone charcoal.

Gunmakers loved this method of "color case-hardening" their actions.
The charcoal adds the surface layer carbide particles to provide that
thin hard surface layer no doubt - but they prized above all the colors
that could be got. You didn't mention the horse droppings ingredient
though :-)
.....
As for the steel strapping, back in the 1960's when I was doing a lot
of black-smithing I hammer-welded about twenty feet of half-inch strap
into twelve inch bar then drew out to a thirty-inch sword blade. That
was taking the Japanese method sorta backwards but I swear that sword
had no trouble cutting mild steel.

-R.S.Hoover

The other Damascus approach I have heard about used the scrap metal
-working bandsaw blades alternated with mild steel strap.
The combination of toughness from the mild steel and hardenability
from the alloy blade looked good (when acid-etched) , and worked well
apparently.
Brian W