Steel colour.

[charlesf]

Recently bought a shingunto at auction signed 'Hizen Ju Masakiyo' exactly the same as in the oshigata database with assembly number '35' painted on to the tang.

Blade is stained and appears to be a gendaito,there is hada visible and what appears to be a water quenched hamon,however,in certain lights there is a blue-ish hue to the blade which makes me think it is not made out of pure tamahagane.

It's impossible to capture as an image so please don't bleat about the lack thereof . . . . . . 

Has anyone else seen the same?

 

charles.

[Rawa]

Possible fire damage?

[ROKUJURO]

As Marcin says, heating up steel to a temperature of ca. 280°C will cause a dark blue colour, resulting in a loss of hardness.

But sword blades can also get a bluish surface colour from a late stage in polishing (KANAHADA NUGUI). It is best seen if you compare blades side by side.  

[charlesf]

7 hours ago, Rawa said:

Possible fire damage?

Thanks for your post,if this was an older blade that might be a possibility but as a gendaito/gunto I think it unlikely,the colour suggests that the steel is either not tamahagane or is maybe tamahagane mixed with Western steel.

Many years ago (1980's) I had a kaigunto with niji mei 'Kanehisa',no stamps which had a similar colour only to be told by my pal Yorkie that good swords had 'white steel' and there is a visible difference between this Masakiyo and gendaito that I have by Emura,Nagamitsu,Tomita Sukehiro and Endo Nagamitsu.

regards,

              charles.

Edited September 26 by charlesf
forgot to sign!

[charlesf]

Edited September 26 by charlesf

[charlesf]

4 hours ago, ROKUJURO said:

As Marcin says, heating up steel to a temperature of ca. 280°C will cause a dark blue colour, resulting in a loss of hardness.

But sword blades can also get a bluish surface colour from a late stage in polishing (KANAHADA NUGUI). It is best seen if you compare blades side by side.  

Thanks for your post,I think the heat damage can be discounted through its overall condition and that it also has some minor hakobori which are slightly larger on one side than the other showing that the blade was correctly hardened.The kanahada explanation is a possibility but I doubt that the surface residue would have lasted 80 years and the WD-40 soak that it's had over the last few days!

regards,

             charles.

[ROKUJURO]

Charles,

I think your idea of steel colour cannot be backed up metallurgically. If I grind/polish historical or modern industrial steel in the same way, they will look the same with almost no variation except possibly in the structure. Basically, TAMAHAGANE has no other "colour" than any other carbon steel, however, in the long range, superficial micro-oxidation and chemical influence may change that as the chemical reactivity of steel alloys can vary. 

It is often said that KOTO blades have a different (= darker) colour than SHINTO, but, depending how they are polished, they can look the same. On the other side, a KANAHADA polish can last for hundreds of years, depending on the use (= abrasion) of the blade.

I cannot follow your thought that differing size HAKOBORE ( 刃毀れ; not Hakobori) on both sides of the blade should be evidence of correct hardening.

[Rawa]

Hakobore [fatal if deep into hamon?] and other flaws

https://weblog.tozando.com/the-katana-kizu-a-flaw-of-the-Japanese-sword/

Edited September 26 by Rawa

[charlesf]

2 hours ago, ROKUJURO said:

Charles,

I think your idea of steel colour cannot be backed up metallurgically. If I grind/polish historical or modern industrial steel in the same way, they will look the same with almost no variation except possibly in the structure. Basically, TAMAHAGANE has no other "colour" than any other carbon steel, however, in the long range, superficial micro-oxidation and chemical influence may change that as the chemical reactivity of steel alloys can vary. 

It is often said that KOTO blades have a different (= darker) colour than SHINTO, but, depending how they are polished, they can look the same. On the other side, a KANAHADA polish can last for hundreds of years, depending on the use (= abrasion) of the blade.

I cannot follow your thought that differing size HAKOBORE ( 刃毀れ; not Hakobori) on both sides of the blade should be evidence of correct hardening.

Pretty simple really,if the blade was not correctly hardened then the edge would have folded rather than chipped.

 

charles

[ROKUJURO]

3 hours ago, Rawa said:

https://weblog.tozando.com/the-katana-kizu-a-flaw-of-the-Japanese-sword/

You can read on their website "KIZU are the evidence of repeated forging" so I would not take all very seriously. Maybe it's the translation....

[I_Kendo_It]

On 9/26/2025 at 9:04 PM, ROKUJURO said:

You can read on their website "KIZU are the evidence of repeated forging" so I would not take all very seriously. Maybe it's the translation....

I guess it's a mistranslation from "folded forging", for example kitae-ware whilst a kizu is also proof of kitae forging.

 

Though even in that case, the article isn't all that well written. For example, hakobore, yakizu and kirikomikizu are typically damage from combat and not evidence of folding.

[ROKUJURO]

I think we mean the same. The article is probably not well translated.

KIZU are damages, and not necessarily caused by "normal" forging. They are no proof of repeated folding and fire-welding, but can accidentally happen in that process.