ROKUJURO

Manuel, while I agree with much of what you say, I would remind you that short-term heating-up a blade will not change the composition of the steel but only the molecular structure at best. Considerable carbon migration - which could result in a change of composition - takes place after long heating cycles or exposing the work-piece to very high temperature. I am on your side when you are asking for evidence - written in old papers or explored by modern research methods - about the making of UTSURI in KOTO times. Where is the information coming from? I would not consider "logic" as proof.

Looks like pine needles to me.

Hi Okan, interesting TSUBA with unfamiliar design for YAGYU (at least for me). Quite solid, looking much smaller and heftier in the photo!

They ARE mushrooms.

As referenced above, cut-up blades are a good material source, but they will have to be recycled in an OROSHIGANE kiln or in early stages of forging a billet. I use them for research and - in case enough material is left - to make knives or tools of them. The sale is only allowed if the sharp blade section is not longer than 150 mm. When the blades are cut up in Japan, the authorities have the value of confiscated blades checked before they are destroyed. This is what I have been told.

Someone tried to "clean" the NAKAGO for a better view of the signature which is a very bad idea. In this special case, it is probably no additional devaluation....

Welcome on board Charles! I hope you will find a lot of helpful information here as well as good and helpful members to talk to! Feel free to show your treasures (personally I'd like to see your Ken Tanto (?) ceremonial piece with Sand-script writings) - we love to see good pictures of them.

Bruno, how safe is it that this TSUBA is not cast? The photo is a bit fuzzy which makes it difficult for me to see details.

Ah yes, thank you! I thought the link was for the rusty TSUBA! As I said, unfamiliar design and technique for me.

Lewis, the photo is not ideal to make a statement, but I would like to know what makes this TSUBA an OMORI school item. Is it signed or accompanied by papers? An unusual design in my eyes.

The HAMON follows the outline nicely; the front end does not look like reshaped to me. If it was made from a broken blade, I think it was a HIRAZUKURI one before. The long NAKAGO makes it look unbalanced as mentioned before. The pictures are not good enough for me to make a statement concerning the age, but the NAKAGO seems to have no patina, so this might indeed be an indication for a recent modification of an originally longer blade.

Patrick, you know that this is probably a cast TSUBA?

Haidar, TAMAHAGANE is produced in a range of different qualities. This is not intentional, but happens accidentally in the TATARA process. The basic material has low carbon content (around 0.3%), while some of the material is coming out of the TATARA as cast iron with more than 2% of carbon. The low-carbon TAMAHAGANE is mostly used for making SHINGANE, while cast iron is processed in OROSHIGANE furnaces to increase the carbon content of iron/steel. Other qualities are selected and sold on the basis of purity and hardness, but without material analysis. As Jacques stated, carbon content in the cutting edges of Japanese swords changed over time. One approach to find the optimum steel may be the fact that carbon content in steel has a peak at 0.78%. At that point, carbon is fully solved in the steel matrix without forming carbides. This leads to a very fine structure and very high hardness which can go up to HRC 67. A higher carbon content does not result in higher hardness. Before the upcoming scientific research in the industrial era, there was no knowledge about chemistry and metallurgy, but there was experience. Steel can be "felt" when working with it, and making small samples, hardening and tempering them, and watch how they 'behave' in bending or breaking tests tells a swordsmith all that is necessary to know.

M, please sign all posts with a first name plus an initial so we could address you politely. It is a rule here on NMB. Your own assessment is quite on the spot. While the blade looks authentic, It is probably a very late blade, maybe later than MEIJI JIDAI, and it is in bad condition. In addition to that, it has a very simple KOSHIRAE in my opinion. But all comes down to the price you paid. If it was really cheap, you could possibly recoup your money in a resale.

Avoiding grease or fatty substances on copper alloys will help prevent green corrosion.