Pincheck

That’s very interesting work Jussi. I did something similar to try and figure out if a dimensional analysis of a sword could in any way be correlated to the approximate age. You hear a lot of people say koto sword were slim and graceful, and that Shinto swords were big and powerful and I wanted to know if there was any truth to that. So I tabulated the dimensions of about 200 swords and plotted various dimensions against age. This is arguably a slightly dubious idea with huge error bars, but what else do you do? My method of estimating ubu length on a suriage sword was to just measure the distance between the first and last ana (usually from the photos) and say that was how much it had been shortened by. It’s probably not very accurate as ana could be placed anywhere and there’s no guarantee that the last one is the original one. But again, what else do you do? Same with age, for mumei swords the estimated age could be out by a century or more. But what else do you do? I looked at nagassa (estimated ubu and extant), sori, kasane, mihaba, all plotted against age. The data came mostly from the web, notably Aoi Art’s comprehensive back catalogue of swords, but other sources as well. 200 swords isn’t many but it takes ages to trawl through it all, and frankly, I got bored of doing it. I can post the plots if anyone is interested. I thought the results were interesting, but in no way guaranteed to be accurate. It is what it is, and all that.

Not any more. https://www.aoijapan.com/regarding-sword-shipments-to-the-uk/

The UK market seems to be pretty difficult at the moment. The various government bans have made selling and importing difficult. I notice Aoi Art no longer ship to the UK. Many of the general militaria dealers aren’t very knowledgeable and there are very few specialists. It can definitely be a case of take what you can find. The To-Ken Society are definitely the best people to talk to. You occasionally see something turn up on sites like Sally Antiques or the militaria dealers but that can be a mine field, caveat emptor definitely applies. If you dip a toe in that water you need a high level of risk tolerance and/or a great deal of knowledge.

It looks like this is an exhibition on the evolution of the samurai as a myth in popular culture, they’re talking about films, video games, fashion, even Darth Vader gets a mention. I get the impression swords will only be a small part of the exhibit, and from the video I’d guess not a very throughly examined part either. I have to be in London in April anyway so I might as well go and find out.

I reckon so. The rate at which this oxide layer grows depends on the carbon level of the steel and you can bet that any other impurities or additives will also make a difference. It has to be said that nugui oil usually contains magnetite and other things designed to allow the polisher to darken the steel. Magnetite is just iron oxide and a thin enough layer will behave to same way. So some polishers may add this effect, thus disguising it’s natural development. Since this mechanism could (theoretically) pick out grains or veins in steel if they varied in composition compared to the neighbouring steel, I wonder if that is (one of) the ways in which chikei and maybe jie nie can appear.

Who knows then. I doubt it’s water ingress, I would expect that to flash off in days not years and it would probably provoke isolated rust spots which this has never shown. Micro-abrasion is possible but I doubt it could account for the profound change I’m seeing. It’s literally developed like a photograph, you honestly wouldn’t think it’s the same blade. I doubt it’s dried on camellia oil as I picked it up from the polisher only a few days after he said it was finished, which was a couple of weeks after he said he’d started it. Plus it would have to be like paint to obscure this hada. No, it hasn’t been lying in the sun. There are a few things I can think of that might cause the sort of change I’m seeing. High levels of phosphorus can lead to a layer of iron hydrogen phosphate hydrate forming on the surface of the steel which can be quite dark. That seems unlikely though as tamehagane is famously low in phosphorus. Hematite is formed during the forging process which unavoidably gets folded into the steel producing fine bands of impurities between the welds. Hematite can be anything from grey to black although I do not know if that colour changes in contact with air or moisture or if it will be straw coloured when freshly polished, although I rather think not. Probably the most likely is that high carbon steel is known to change colour on contact with air. A very thin layer of FeO, Fe3O4 and Fe2O3 forms on the surface of steel which causes it to go through several color changes due to the way it reflects light from the top and underside of the layer, in the same way an anti-reflective coating on a glass lens works. At 50nm thick it looks pale yellow, 70nm it’s straw, at 90nm it starts to look more brown, by 100nm it’s a blue gray, finally looking black by the time it gets to 150nm thick. My guess is there is a very thin layer of this stuff at varying thicknesses depending on the grain boundaries in the steel which is picking out and highlight the hada as it grows.

I have a sword of unknown origin. For background, it's mumei, o suriage but still quite long with a 686mm nagasa, it has a noticeably narrow shinogi-ji, little hira niku. No idea what it is or even approximate age, but I like it a lot. Anyway, when I first got it it was in poor shape. It was in gunto mounts of better than average quality with a defaced silver mon. Well out of polish with quite a bit of damage, but something about caught my eye. Whoever the polisher was back in the day, he did a marvellous job as the lines were so crisp you could shave with them. I thought it worth the effort to save so I sent it away for polishing. Prior to the polish, there wasn't much you could say about it other than it had no discernible hada and had a laser straight suguha, but the steel was dark grey, almost black. Immediately post polish, it had no discernible hada and a laser straight suguha but the steel was light straw colored, almost yellow. Fast forward a few years and the steel has gone dark grey again, almost black and now it has a pronounced ko-itame hada, which reminds me of sand, with a few patches of coarser hada and some that even looks like massame hada. It also developed some shirakke utsuri and jie nie. The change is quite remarkable and I was wondering if that is normal? I don't do anything to it, other than the occasional wipe with clove oil (not oil of cloves, the nihonto specific clove scented mineral oil). Pre-polish https://i.ibb.co/G3sBXXRJ/Prea-IMG-0703.jpg https://i.ibb.co/9mnsjgzP/Prea-PICT0013.jpg https://i.ibb.co/yFqh5FGQ/Pre-IMG-0700.jpg Immediately post-polish https://i.ibb.co/NnxW1K6v/Post-IMG-0730.jpg https://i.ibb.co/4wBhSwVx/Post-PICT0036.jpg 3 years later https://i.ibb.co/1f2tjMc3/Full-Length2.jpg https://i.ibb.co/Ng7WJ3fW/IMG-1579.jpg https://i.ibb.co/nMJw1wmS/Devimage14.jpg https://i.ibb.co/0VMX42qN/Devimage20.jpg[ https://i.ibb.co/cKRwtGTF/Dev-IMG-1564c.jpg https://i.ibb.co/39TXw6XM/Dev-IMG-1566.jpg Edit: Unfortunately, it looks like imgbb has compressed all the detail out of the photos which rather ruins this post. Not sure if there's a way to fix that.

I’m not sure if I’ve posted this in the right section but the link below seems a little fishy to me. I’m no expert but the tassel appears to be a company grade officer, not an admiral. It claims the blade is signed by Yoshindo Yoshihara. The only Yoshihara I know of didn’t start making swords until 1965 and this sword is supposed to have been surrendered in 1945. It doesn’t look much like that Yoshindo Yoshihara’s work to me either, looks more like an oil quenched Gunto blade, but maybe there was a ww2 era Yoshihara I don’t know about? What do you guys think? https://www.michaeldlong.com/product/Japanese-ww2-naval-katana-surrendered-by-admiral-fukudome/

I can’t imagine why someone would go to the trouble of carving a kiku mon and then not sign it, but anything is possible. It could be that someone has removed what they thought was a gimei signature and repatinated the nakago. It looks like there might be a slight divot, a different texture and maybe a change in colour where a signature might have been. But that is pure speculation. Whatever it is, I like it.

Thanks guys. I naively thought the outer leaves were lily pads, not sure what the other ones are. Aoi leaves make more sense I suppose. It’s not big, only 75mm across, and correct me if I’m wrong but I was under the impression that a lot of the more functional tsuba were a bit bigger than that, so I’m guessing later (maybe edo) rather than earlier (muromachi or before). But I really do know nothing about tsuba. I got it for a sword I used for Iaido, back when my knees still worked.

I’ve had this tsuba for about 35 years but I know absolutely nothing about it. I was wondering if anyone had any thoughts? It has no markings, it’s the same design on both sides, it’s made of iron with some kind of yellow metal inlay. Any comments would be very much appreciated.

ChatGPT keeps the chat history in its contextual memory so you could feed it information and then ask it questions about what you’ve told it. That history is gone when you start a new chat though. But you can train a custom GPT and save it so other can use it. There are input limits though, I think I read something like 32k tokens, a token is a word fragment like “ing” or “tion”. AI is generally good at things that are incontrovertible mathematical facts, like computer code, and really bad at woolly opinion based things with vague and inconsistent descriptions, like kantei.

After a lot of trial and error (mostly error) I finally got some decent photos of my katana. I have no idea how old it is, or what school it might be, but I like it.

Not that it adds much to the discussion but I also have a showato katana signed Hoshiya Yoshinaga that looks a lot like yours. https://i.ibb.co/9gXS1mM/IMG-1203.jpg https://i.ibb.co/t8QxkRY/IMG-1204.jpg