Copyright Robert Cole 2014 - No copying or distributing

NAKAGO - Sword Tang

In consideration of value and history, there are two and nearly equal parts to a sword, the polished blade and the NAKAGO.

It is said that the secret of a sword's age is in the NAKAGO. Perhaps the foremost rule concerning swords is the inviolability of the tang. It is here that age has had its way, unfettered. Its mark a history, to be read like an open book.


There are two visible forms of oxidation: red rust, and black.

Red is destructive. Black is protective

When a NAKAGO is first finished, its freshly filed surface is clean and bright. Edges are sharp and defined. Depending on carbon content and steel quality and the degree of care the sword receives, the oxidation process follows a predictable course. Surface color and condition have long been a teller of age.

The NAKAGO in many ways was the smith's personal domain. His signature resides in its curve, in its planes, in its ridges, in its finished edges and file marks, and in the shape as much as in the inscription itself.

Left to itself, and with good sword care, the NAKAGO can stay quite clear for twenty to fifty years. At approximately seventy-five to one hundred years, some amount surface corrosion can be expected to take hold.

While the edges, ridges, file marks, and signature are still in sharp definition, black oxide can be seen emerging from red. Red rust is a hydrated ferric oxide Fe2O3. When it falls from a sword the more structurally stable FeO (ferrous oxide) is left as a film on the surface. FeO appears black. A NAKAGO becomes darker from the increasing thickness of ferrous oxide surface film, inevitable with age. Color-hue varies with the differing trace elements of actual source steels.

Eventually, this deepening black blanket inhibits the invasive oxidation process dramatically, protecting the steel within.

The general rule: the darker, the older

A NAKAGO from MUROMACHI times, mid-1400, can appear deep black with soft, smooth texture to the surface very much like bar soap.

There are old TACHI with NAKAGO surfaces resembling sealing wax. The importance of NAKAGO surface texture and color is ABSOLUTE.

It is as important as any other aspect of Japanese Swords.

NAKAGO surface condition tells age, the care given, when the sword was altered and when it was injured; it tells when and how many polishes were sustained and, along with MEKUGI-ANA, when and how many mountings clothed the weapon throughout its history.


To the adept appraiser, the NAKAGO whispers truths and lies.

Nowhere is this whispering less subtle than in sword inscriptions...

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