An oshigata is a drawing of a sword, focusing on its hamon and shape. They have been used since before the advent of photography to record and document swords for reference. They can also serve as a fingerprint of sorts by focusing on the nakago which is transferred to the paper by rubbing.
A few heads up in this area are worth noting.
There are various styles of oshigata, from highly accurate to approximations. In old books, often times very little attempt is made to record the chisel strokes of a signature. Instead, it seems that an outline of the nakago was made and then the signature written in directly by the artist. These end up being only approximations. They tell us some good information about what this blade was but make it impossible to use for measuring authenticity in the modern age.
Note on the Sadamune on the left (via Markus Sesko): The comment for the blade on the left in that pic reads: “Matsudaira Ukyō dono ni kore ari Takagi” (松平右京殿ニ有之髙木) – “Owned by Matsudaira Ukyō, Takagi”. Ukyō was Matsudaira Terusada (松平輝貞, 1665-1747), daimyō of the Takasaki fief of Kōzuke province.
So the blade might be Takagi Sadamune as an attribution…
Oshigata is an artistic skill so it’s limited by the vision and execution of the artist. Earlier Jubi oshigata are often almost freehand drawings with no detail whatsoever.
Older NBTHK oshigata on high level swords show the limitation of the oshigata artist considerably compared to modern ones. The older ones from the 60s and 70s mostly hint at the activities in Masamune while the newer ones take pain to illustrate the marvelous nie and ko-nie and all activities in detail. Furthermore the yellowing of paper on the older oshigata makes it difficult now to capture whatever detail is actually there as the ink fades and the yellow paper darkens, converging together into a muddy hue.
Contrast this oshigata to what the NBTHK produced in the most recent Juyo shinsa.
Without a little bit of context, it is impossible to consider that the above three swords are related. The discrepancies are almost all due to the execution of the artist in producing these oshigata.
In modern NBTHK oshigata, effort is also made now to capture utsuri as well as hataraki in the jihada. Occasionally an artist will draw in portions of the jihada if the patterns are significantly important or if they stand out with significant hataraki such as with Norishige. The following tanto is not hitatsura but features very strong glowing chikei following its matsukawa hada.
The primary trap revolves around mistaking the oshigata for the sword. An oshigata is an artist’s impression of the sword. It is limited by his skill, handicaps, biases and execution. At the least case, an oshigata shown online is:
- an electronic capture of…
- a physical drawing of…
- a mental concept of…
- an image projected on the retinas of…
- an artist looking at a sword, possibly in imperfect light.
So in a way, it’s like the “game of telephone” where at each stage some distortions are introduced, either intentionally or mistakenly or even without knowing, that reduce the fidelity of the final product.
A case in point to warn about deciding too much on the oshigata… I once rejected a sword once out of fear of wasting the owner’s time after consulting the oshigata. The oshigata told me the boshi was thin and so I thought, the sword was going to be a poor purchase. The owner made an effort to show me the sword anyway, and to my surprise, the boshi was thick, and healthy and perfect in every way. I bought the sword immediately, and furthermore it went on to pass Tokubetsu Juyo. Had I confined myself to a decision based on this oshigata I would have made a severe error and passed up a great sword.
The converse applies of course.
The Trap of Bias
If the oshigata is drawn by the vendor, then the vendor may have… let’s call it… an overly positive conception of the item he’s drawing. Not always, but it’s something to be on the lookout for. In which case, everything they draw is somewhat embellished and everything looks like a Kokuho once the work is done, and weak points are consistently glossed over. It’s works out like an instagram filter for swords. Everything looks cool and great, no matter how blah the reality was.
The Trap of Skill
due to skill limitations, what an artist is capable of generating with his hands, do not match the reality of the item. In this case weak points could be missed or strong points lost. The oshigata becomes a vague echo of the item. What it actually looks like is a random walk some distance from what the oshigata says.
The Trap of Handicap
In the case of getting old, we all will lose our vision. What was crisp and clear may start becoming muddy. It’s very difficult to subjectively divorce oneself from the internal monolog fed to us by our own brains. In this case there is no solution other than to know your limitations as an artist. Or, to know the limitations of the artist in question and that they just may not physically see something properly anymore when they document it. That said a lot of old experts seem to have no problem in producing excellent oshigata. But eventually, we all have physical limits from age that cannot be beaten and glasses are no substitute for young eyes.
The Trap of Execution
In the case of everything else being fine, someone can still just phone it in in a half assed way. This can be due to time constraints, or lack of trying, or lack of care. In this case the artist could do better, but for some reason, doesn’t.
Another thing to consider is that the state of polish may change between the time of execution of the oshigata and when you get to see the sword. This polish change could improve the sword or could worsen it. A sword could haze over and become rusty or a very old oshigata could in fact be a much healthier version of what you see now in the sword. Or activity could pop out that was hidden from abuse and years of uchiko grinding.
Because of all of the above, one always has to look at an oshigata as an informed opinion. It’s a starting point for telling you what to look at in a sword, but don’t be surprised if you see discrepancies or an item turns out to be better, or worse than was described in an oshigata. The context does matter, factor in the ancient oshigata as vague documentary interpretations of the subject matter, and early NBTHK oshigata as crude representations that lack some detail. From those expect the reality is probably often to be better than what you see in the pictures.