Reason Behind Kogatana Shape?

[obiwanknabbe]

I was curious if anyone knew why kogatana are shaped the way they are? Why the high angled cutting surface? Why only polished on one side and signed the way they are? And why no mekugi-ana to tightly secure it?  It seems like an archaic design that never changed. 

 

Thanks 

 

Kurt k

[IanB]

Kurt,  Since nobody else has stepped in I will. Kogatana are made by welding a piece of high carbon steel to a piece of iron, the steel being on the lower side of the blade. Apart from the advantage of not using much steel, this structure is to some extent self-sharpening since the iron wears faster than the steel. The reason why only the underside is polished is because you cannot get a hamon on the iron so there is no point in polishing it - it is just filed up. 

Ian Bottomley

[Stephen]

I did not know that, always thought it was one piece of steel. Thank you Ian and thank you Kurt for asking. 

[Brian]

News to me too.

[nagamaki - Franco]

Hello,

 

News to me too, funny, because when I had my kogatana polished the polisher told me all skin steel. As far as shape goes it is my understanding that this shape goes way back to the time of the very first swords and tools.

[Henry Wilson]

The Tosogu no Kigen and translation might shine some light on the subject.

 

http://www.japaneseswordbooksandtsuba.com/store/books/b675-tosogu-no-kigen

[obiwanknabbe]

Well there is something i didnt know.  Cool. Thanks guys. 

[Stephen]

We havent heard from John S, i think he forged one when he was in Japan, I assumed it was just hammered out of one stock. John?

[Stephen]

Too bad vid is no longer up

http://www.militaria.co.za/nmb/topic/1018-paul-martin-making-a-kogatana/

[John A Stuart]

Hi Stephen, We did the chiseling of the mei and yaki-ire on already prepared blanks. We did some forging, but, it was minimal as the course was not long enough to learn how to hammer to shape a proper example that would be worth getting polished as a keepsake. It seemed to be a type of two layer process, but, could very well be monosteel in many cases for ease of construction. Some kogatana even seem to be poor steel, low carbon. Those $40 filler blades. John

[Stephen]

Thanks John