For those that like Choji

[Alex A]

Always like to see good Sukekane (and others) Choji. Like looking into a fire.

 

Very nice, http://www.sword-auction.jp/en/content/as19312-刀%EF%BC%9A備州長船住横山祐包明治ニニ年二月日友成五十八代孫-katana-bishu-osafune-ju-yokoyama-sukekane

[Ken-Hawaii]

Nice choji, indeed.

[Alex A]

What i like about this particular blade is that both sides of the hamon stand out as excellent

 

Often with chogi, one side of the blade is far better or more interesting than the other side or there are parts of the hamon that go rather dull in places. 

 

Great sword.

 

Never really read much about blades being better on one side than the other, might be a decent topic.

[Apercus]

I’ve thought about this difference between the appearance of choji on each side of the blade and proposed a possible explanation years ago. I believe the early application of choji in some schools was created by a different process than latter attempts. Instead of using clay and a differential quench a blade can be heat treated by a differential application of heat. I have heated a long block of steel/iron to a bright yellow heat and used it to introduce heat to the edge of a blade. I quench the blade when about 1/3 of the blade width is past the transformation temperature. This also tends to produce utsuri if the exterior steel has a medium to lower carbon content. Utsuri, which I believe is banite, forms at a lower temperature than martensite.

 

If the blade has had deliberate hammer marks left on the surface (think small round ball peen hammer marks) then a choji hamon may appear after heat treatment and polish. The martensite will form at differing depths because of the depth of indentations. There is also the influence of how and where the vapor barrier appears in a water quench. There are ways to enhance this effect which would require too much space here to describe. When you hammer indentations on one side of a blade and then flip the blade over to hammer indentations on the other side some of the profile of the first side is removed and the appearance of choji will lessen on that side. I’ve done this at a forge and seen the results I have described. I’m sure the smith would be aware of the effect and I would expect the best choji to appear on the side with the signature.

 

Sorry for the long post. This was just the results of my own speculation and experiments a long time ago

 

ShannonHogg

[Alex A]

Thanks Shannon, appreciate you taking the time to share your findings, very interesting.

[16k]

Lovely sword,

 

And very interesting explanation, Shannon.