Ford Hallam

Glen With reference to the paper by Shinya Isogawa, you didn't say specifically which paper but as there is only one of his research papers available on-line in English, I'm assuming it's this one? https://www.jstage.jst.go.jp/article/isijinternational/54/5/54_1123/_html There seems to be no mention of Edo period casting in this paper nor are the following points you say are derived from the paper in evidence. Is there perhaps another version you've found that does offer these suggestions? I only ask because if they are supported by archeological evidence I'd suggest that while not quite 'the smoking gun' it comes pretty close. I'd also add that melting cast iron is impossible "at a relatively low temperature" . Typically 1200 degrees C is needed to do the job, this is really at about the limits of a bellows fed charcoal fire. The Chinese, of course were producing vast quantities of cast iron more than 2500 years earlier but this utilised blast furnaces, was a huge government run industrial operation involving around 3000 men, according to existing official documents. The point being that casting iron is not a quick nor simple process. The "widely available, distributed cast-iron ingots" you cite we in all likelihood import from the mainland. This trade is well documented in pre-Edo times. This aspect and the broader issue of casting technology is amply covered in Prof. Gina Barnes' superb 'Archaeology of East Asia'. Prof. Barnes has been kind enough to assist me and guide my own research. And simply filing a cast surface to apply nunome-zogan will simply not work. Ford

Glen, sorry, yes I ought to have been clearer. While it seems the 'go to' approach, being evidently the more efficient method, of drilling and chiselling etc. was used in most usual situations, where the cuts were required to be exceptionally fine it does appear that a wire with an abrasive, possibly garnet powder and oil, was employed. In fact one of the 'tools' listed in the tool descriptions in the Soken Kisho is exactly that, a length of fine iron wire. Presumably for this purpose. I would add though, that we might regard this extra fine method as being quite specialist and not exactly standard workshop practice. Even today with modern saw-blades I'd struggle to cut a 5mm plate with a 0.25mm blade. I'd imagine that using a more pliable and less brittle wire may in fact be a more reliable and less frustrating way to cut those fine lines.

Hi Brian sadly no, all we have to examine are fairly rare survivors from the very late Edo and Meiji periods. Some of Kano Natsuo's tools, for example, are held by the Crafts museum in Tokyo, part of the University of arts. there's a good metalwork museum in Niigata, but again Meiji period kit. The odd few chisels exist here and there but nothing very early. A few (4) belonging to Noritsuke The Soken Kisho offers a few rough illustrations and and some lists of tools, although some a bit hard to accurately imagine. Suki-tagane - open-work chisel ie; sukashi chisel me-tagane - woman chisel...no idea! otoko chisel - man chisel...again! natsume tagane - tea caddy chisel, maybe with an edge that is shaped like a natsume lid? I've made one like that and use it quite a bit, cant be sure it's the same thing though. shibu tagane - four sided chisel...your guess is as good as mine Different sized files were in use; Oyasuri, koyasuri , chuyasuri large, small medium, hira and maru, flat and round, hangetsu-yasuri half-round file, sumi-yasuri corner file? and natsume yasuri. There was a shitodome file, itome, hausu, uroko and koke files; fine line file, thin blade file, fish scale file and moss file. It's the same with the European goldsmithing tradition, how we work today is different in almost every respect to how work was made even 200 years ago, never mind 500. This is something I've been exploring in my own goldsmithing practice in recent years.

Hi Roger In fact inlaying patches of the same iron into a plate was pretty much the standard approach to creating relief on a tsuba black. I see evidence of this every month when removing rust and corrosion which serves to 'etch' the ground and making the edges of the inlay easily visible. Generally speaking a larger and more simply shaped patch is inset and then the exact form outlined and carved out. This means the seams are not exactly around the raised form and can more effectively be worked tight. It also means the raised form can be carved and adjusted more freely. The ferrous material Edo tsuba-ko used was, almost without exception and always with inlaid work, a finely processed wrought iron. This is quite soft and carving and inlay is quite simple, if one has properly shaped chisels and punches and knows how to use them effectively. The depth of the cavity required for these inlay patches depends on the size of the piece and around 1mm is enough to secure an inlay so that it can withstand subsequent chiselling etc. This is a little film clip of a piece I was working on a few evenings ago. The base of the tree and its roots were carved out of just such an inlaid patch that extends beyond the outline of the tree itself. regards Ford

Roger, in answer to your question; the modern jeweller's piercing saw and its very thin blade only became available in Europe in the late 19th century. I imagine its use may have been introduced to Japanese craftsman sometime in the very late 19th century. We start to see obvious saw pierced-work, in things like finely fretted incense burner lids etc, at the start of the 20th century. Prior to this time tsuba and the like were drilled, chiselled and filed out. I would add that as piercing saw blades are easily breakable and I imagine were not exactly cheap back then, probably imported initially too) their use in cutting out iron plate would possibly not been seen as all that attractive or economical. I've not seen any evidence of Japanese manufacture of blades at that time but I wouldn't be surprised if they rapidly developed a process fro making blades, even in individual studios....more repetitive work for apprentices! We take it for granted today that using a saw is the most sensible approach but I have some doubts. In fact I've seen film footage ( from the 70's ) of the late National Living Treasure 1965, Tahei Yonemitsu who was a Higo craftsman, where he is clearly filing out an opening in a tsuba blank that was created by 'chain drilling' ie; a series of small holes drilled in a line to allow a patch of metal to be more easily broken out of the plate. The refined by chiselling and filing would then follow. So my feeling is that traditionally trained tsuba-ko didn't adopt the piercing saw. I'm hoping sometime to make a sukashi piece by proper traditional methods for a film to see exactly how that approach works and what it's advantages might be. Those Saotome tsuba btw, often have every other spoke as an 'inlaid' strip of iron, thus creating the illusion of a more tightly pierced pattern regards Ford

Glen I will direct this post to you directly It seems to me that your defence of your theory is becoming somewhat desperate, not to mention distasteful. You have tried to insert a sneaky sleight of hand by suggesting that any criticism or non-acceptance of your theory represents an opposing theory. This is, of course, quite absurd. YOU have proposed a theory, that ferrous tsuba were cast in the Edo period. Therefore the onus is entirely on you to provide convincing evidence and rationale to support your assertion. To my mind you have singularly failed to do so, I have merely offered a few (there are many more objections I could cite) criticisms and pointed out what I regard as very tenuous suppositions. There is no opposing camp of 'non "believers' in Edo ferrous tsuba casting'. Your attempt to frame this 'exploration' in this way is disingenuous and divisive. One can't effectively 'prove' a negative proposition, but the proposer of a positive assertion; ie; YOU, must provide coherent and verifiable evidence if you expect your proposition to be treated as reasonable. Here-say, assumptions, and suppositions do not a valid argument make. And ad hominem attacks against myself only serve to undermine your credibility. You accuse me of attempting to demean the reputations of dead men. That's a disgusting low to stoop to in the defence of your argument! I made perfectly respectful criticisms of specific points, perfectly reasonable and usual in the reading and analysis of any work, by a living or deceased person. But I waste my time here wading through your Gish Gallop. I have no further interest in engaging in such an ugly and poorly informed discussion. My regards to all and thank you for bearing with me. Ford

So....if we, just for a moment, accept that somehow the Japanese craftsmen managed this remarkable technological feat of casting small, around 200g, and thin complex forms and managed somehow to cast repeats of these models why then, are really poor quality dodgy tsuba the only such cast artefacts we can examine. Surely such an amazing accomplishment would have been used for more useful and interesting object manufacture also? Why are there no other Edo period cast iron artefacts of similar scale and detail/complexity around for us to examine? I was also amused to see M. Joly being wheeled out as 'evidence'. He never visited Japan, had no direct experience with Japanese craftsmen and gleaned all of his understanding of tosogu from his Japanese dealer suppliers. Hardly a verifiable source for any technological clams I'd suggest, not that M. Joly provides any sources for his comments with regard to these spurious castings, he simply asserts. Also, suggesting that there are numerous cast tsuba in Western museums, with verifiable provenance, hardly advances the case either because in every case of these verifiable donations to these museums, for the most part, post date the end of the Edo period, 1867. So, specifically, which tsuba were donated to these museums prior to this date? And let's remember that Western museums themselves were still in their infancy at that time too, so hardly the reliable and properly documented archives we expect our present institutions to be today. It's probably worth considering that at that time the Japanese dealers and collectors themselves were only really beginning to look at tosugu in a more unified way and trying to put together a history of sorts. It was at this time some many of the labels we take for granted were invented. Kamakura tsuba, we don't know where they were made really, the name is just a loose association with the carved lacquer work, no more. We cant say for sure where or precisely when even Owari guards were made. Can it be shown that Owari was even a term used for those guards in the Edo period? Onin tsuba, absolutely no evidence that the brass inlay was done in the Onin period. Just a fanciful invention! Musashi's remarkable output of tosogu, can anyone show how any of these now papered pieces have been authenticated....I don't think so. Nobuie tsuba, two makers....one signs fat one thin, one first generation one second generation. How do we decide....flip a coin! we don't know their real names, were they lived or even when they lived. Shingen tsuba, the hilarious suggestion that Takeda Shingen used to weave them while waiting to go into battle, like an old lady knitting while waiting for a bus! and yet this drivel is repeated ad nausium every time one of them is up for sale. Is there even one shred of evidence to link the things to Takeda Shingen....I dont think so, but the fairytale will persist. I could go on and on....and such is the dogma we accept without challenge. So I suppose if someone wants to invent a 'hidden' Edo period casting technology to validate crap fake tsuba what's the harm? It's no wonder serious art historians avoid the whole subject entirely. It's hard enough to tease out the truth from history, it's made impossible if we keep dumping more mud into the water though.

Dan I have to take exception with your suggestion that collecting is firstly about fun, specifically in this context. The real issue here is the pushing for acceptance of an unverifiable theory that cast iron tsuba were made, according to your suggestion, as early as the 1600's even. The problem is then that unknowing or unscrupulous sellers can take advantage of this area of vagueness and pass off fakes as somehow being legitimate Edo period artefacts. It's amusing that you took such pains to demonstrate so clearly that my "joke' about a samurai faxing Lincoln was impossible because according to one website you found there was no suitable cable available at the time. Yet in defence of you own thesis you're happy to posit all sort of alternative explanations to fill the gaps in your required evidence trail to support the casting of iron tsuba in Edo Japan. What if I claim that the unrecorded cable my 'theory' requires was actually a secret project operated by the Satsuma clan, in defiance of the Shogunate's laws, so that they could learn about the outside world. When the black ships arrived they realised that they couldn't trust intermediaries so they pushed ahead with their cable laying efforts, first to the Ryukyu's, then Hawaii. The goal was of course the trade delegation there, from whence a reliable communication route might be established with the US government more directly. All treasonous so naturally kept top secret with no incriminating evidence or records being kept. It's possible...gotta keep an open mind As for being considered 'a leading expert' or whatever, not my claim so please don't be so rude as to try and demean what I have achieved, it's a strawman argument at best. And if you're looking for a comparable specialist in the craft/technology of tosogu in Japan let me know when you find them please. Spoiler alert, you may be in for a disappointing let down. Anyway, everyone can believe what they like and spend their money on whatever they wish also. I would suggest, though, that a few hours perusing the numerous late 19th century and early 20th century published catalogues, huge tomes most of them, with thousands of pieces recorded in photographs, many surprisingly good images too, as well as any pile of pre 2000 auction catalogues searching for obvious cast iron tsuba might well be like searching for a needle in a haystack! If anyone is in the Dartmouth area anytime feel free to contact me in my studio at 17 Foss street and I'll give you free access to about 6 feet of such material to search through. I've not seen anything in the slightest way convincing yet, and my trained craftsman's eyes have been intimate with these sources for more than 30 years. Your milage may vary, as they say Actually there is one more quite relevant point to make; Throughout this thread various images of tsuba, some papered even, have been presented and various details in the surface highlighted as being 'evidence' of casting technology. The problem I have with this approach is that firstly it is based on a second hand 'imagined' idea of what tell tale marks might be left after casting work. Has anyone here, or anywhere for that matter, actually recreated a ferrous tsuba by the means suggested and can we see what the results actually look like. Obviously this is a hypothetical question, we have no clue what the supposed Edo period process of iron tsuba casting would produce. All we have is a patchwork of ideas cobbled together from various contemporary craft and jewellery sources. In contrast to that area of assessment who in this discussion actually knows have iron tsuba were made by hand? I don't just mean the basics, but the actual nitty gritty of taking forged plate to final carved and patinated form. What are the tell tale signs and details that those processes leave and how do our modern working methods differ from the Edo period? what do they look like? and how do they differ from these other imagined Edo period cast iron tsuba? Just as one very simple example of the dangers of uninformed supposition... Dr Lissenden saw clear evidence of a cast seam in the interstices of his scrolling Namban tsuba. I saw evidence of drilled holes and chiselling from each side leaving a little 'lip' where each chiselled surface met roughly in the middle. Why did I see that? Because I've done it myself and I easily recognised the same traces of workmanship. But if you don't fully appreciate that tsuba were not cut out with a saw blade but drilled and chiselled as routine then that possible interpretation is unavailable to you and you're forced to base your conclusion only on your limited understanding. Beginners mind is often woefully devoid of useful or relevant data in many situations. My consultant doctors would get short shrift from me if they went all 'Zen beginners mind' with me Anyway, once again I've written too much but its apparently all grist to the mill

and another thing The so called Nara moulds are, to my understanding at least, not remnants of casting moulds at all. A casting mould requires at least two interlocking halves AND runners, which are vents to allow the internal air, suddenly superheated (and expanding) by the introduction of very hot molten metal, to escape. What we see there are pretty common workshop relics, impressions made with clay of finished pieces as records. The finished piece is placed on a board, dusted with fine charcoal powder so that the clay will easily come away when dry, and left to harden. As for casting copper, no one did it! Copper can readily absorb 100% of its own volume when molten so that casting it into a closed mould or even ingot mould invariably produces an item with severe porosity (fine pin-holes in the body of the metal) and often completely friable and unusable. This is presumably why the Japanese developed their method of Yudowake, casting copper into water, as detailed in the Kodo-zuroku (1801). But even this process delivers ingots with porosity on the upper surface under the best of conditions. I've cast dozens of such ingots, but they all had to be thoroughly forged down to make a usable plate. There are quite a few such films on YT now, it seems I birthed a monster

Just as a Parthian shot; it'd be refreshing to see some references to proper history and technical books rather than the usual unverified internet fluff that is the usual fodder.

Brian, you're a very naughty man It seems my friend Jean has made a good job of holding up the practical side of the discussion, and I've previously written a shed load on the subject here too but some dead horses apparently won't stay dead For me the matter is relatively straightforward. I try to consider such possibilities as cast iron tsuba in as scientific way as possible. By which I mean I will examine the evidence. I'm not interested in possibilities, possible is not probable. As I taught my sons, It's possible there's an elephant in the backyard right now....but it's highly unlikely. Is there any compelling evidence that elephants even recently visited the yard? It seems to me that the the problem starts with 'tsuba' that are clearly produced by casting. Multiples even, which suggest a method of economical reproduction. These cast pieces are, almost without exception, pretty poor examples of the tsuba makers art. To be blunt I can't see why anyone would want one other than as a coaster or paperweight....my desk would not be so besmirched though . Here I'm in mind of our dearly missed friend Guido, he'd be appalled. So these things were cheap in a market of much finer wares, even the most simple handmade pieces. So who would buy them in a culture that valued craftsmanship and where one's status and culture was on show in what you wore and displayed... a world were tosugu were a fine art? Only the culturally ignorant (of Japanese artistic culture) , uneducated in Japanese value systems, beguiled by superficial trinkets and with money to spare would give these products more than a cursors glance, imo. So we have, as exhibit one, poorly cast copies of tsuba. But with no context, no certain way to establish when or where they were made. I've been studying tosogu for about 45 years now, and have a hefty library of the earlier tsuba collectors catalogues. These cast pieces seem to be conspicuous by their absence. It seems to me their appearance is relatively recent. Or old school collectors and scholars simply rejected them as the dross they are, regardless of age. Those who would argue for the possibility of Edo period manufacture have a mammoth task. Whether they were cast in the Edo period or not is not a simple yes or no, equal probability equation. In the absence of convincing or compelling evidence any theory is merely empty speculation. All the theorising in the world does not in any way advance the truth of an idea without some 'real world' verification. A line of text, a cast tsuba on a sword registered in a temple somewhere...a paragraph in the soken kisho or the Ci Yuan. Endless discussions on aspects of metalwork, Japanese iron casting blended with partial and irrelevant notions of modern lost wax casting and mould making, by theorists with no practical or relevant experience with which to even evaluate or critique their own imaginary technological histories reminds me of the old 'reductio ad absurdum'; "how many angles can dance on the head of a pin" . Dr Lissenden's explanation of a possible Edo casting procedure is unconvincing and far too simplistic so as a defence of the notion that is was possible it remains a fanciful idea at best. If we are to entertain this sort of speculative thinking we might just as convincingly 'demonstrate' that telephones could have been made in Edo period Japan too. I'll end by sharing this, sent to me by Greg Irvine, recently retired Senior curator at the V&A, so a serious scholar, The Samurai, as a class, were dissolved in 1867 The 'printing telegraph', the first fax, was invented in 1843 Abraham Lincoln was assassinated in 1865 so There was a 20 year window in which a Samurai could have faxed Abraham Lincoln.

Colin on my youtube channel, there's a link in my post now you'll find loads of films there btw.

Hi Colin In a recent film we made on old iron I discussed a very similar tsuba of my own, that I labelled Higo, Kumagai. In terms of style and details I think you'd see the similarities. That group might be worth looking at perhaps. At 21:24 regards Ford

Here you go, a copy of the original print. Double click for a full size image

Glen, I don't know that judging this particular style or school of work on the finesse of the blacksmithing is really all that meaningful. Clearly what some might see as poor forge-welding technique was of little concern to the early Akasaka masters or impacted on their popularity, those masters who are most revered by connoisseurs. This obviously visible method of construction, along with the weld openings, is in fact a kantei point for early Akasaka work. We might speculate why is apparent 'flaw' was accepted, fuel cost resulting in a very minimal amount of material preparation, I've made plate by consolidating tatara iron in just two folds myself. It sticks like s**t to a blanket!, a few more folds and it'd be good for a blade but the bare minimum seems perfectly adequate for tsuba of a particular aesthetic. In fact we might imagine further that the basic humbleness of the basic plate was appreciated precisely because it showed so readily it's lack of pretension. These are all well recognised and respectable aesthetic expressions in Japanese art. Japanese potters made perfectly refined tea bowl and cups yet it is the rough and irregular Kizaemon tea bowl, probably made as part of a batch of dozens or more by an anonymous Korean potter in a matter of minutes , that is revered as the Holy Grail of tea bowls in Japan. I suppose this all brings us back to a fundamental point of art appreciation and critique, that is that is ought to be considered in its own historical and social context to be fair or meaningful. Of course anyone is free to like or dislike whatever they choose, as you say; "to each their own", but I would suggest that to 'properly see' something made so long ago and far away we need to try and put aside our very different, modern, world views and tastes and to understand why it is as it is and what it conveys in its own terms.

From my perspective I see absolutely nothing in this tsuba to suggest that it isn't a perfectly genuine Edo period (possibly early to mid Edo) tsuba made from hand wrought iron. The 'seams' are commonplace in hand wrought low carbon iron, as anyone who's processed tatatra produced type material can attest. There are lots of other more subtle textural effect in evidence in the iron that all evidence it being hand processed material and hand worked. Additionally, the tsuba appears to be an early-ish Akasaka piece. One characteristic of the first three or four generations of this school is precisely a three layered or sandwich construction. Supposedly the outer plates are more refined with the core less well worked. A bit like the kobuse style of sword construction. I think this is a very attractive and desirable example, the design is text book, and the workmanship essentially spot on. The overall condition is very good, it's a classic earlier Akasaka tsuba that would be a decent addition to any Akasaka collection.

It looks to me that the filler material that was used to secure the dragon and ken element to the nanako ji-ita is a matsuyani mixture. Essentially pine rosin and fire clay. It's very runny and sticky when hot/warm and rock hard when cold. I've encountered it many times when restoring Meiji period pieces that were constructed out of many components. When it was fresh it would have been much more tough and resilient but over time the remaining oils and resinous ingredients evaporate leaving the mixture characteristically dry and friable, like this. The use of matsuyani to stick decoration onto a kozuka is definitely not an Edo period norm I have to say I'm a little concerned about recent suggestions here on the NMB that vinegar, salt or other such potentially corrosive solutions be used in the cleaning of tosogu. Unless you know pretty well what you're dealing with in advance and know how to put it all right when you're done you may well be opening a can or worms/Pandora's box of trouble.

I've seen entries in various dairies of samurai doing tours of duty in Edo where they list monthly expenses etc. Two I can think of off hand were regarding a saya repair, to the urushi, and the other a rewrap. Rewraps were apparently needed yearly. The inference being that it simply wouldn't do to be wearing a sword as a retainer that wasn't kept in decent condition, and I'd suggest that'd include worn patina. A worn iron patina would also be vulnerable to fresh rust which could soil one's kimono too. So it seems reasonable to think that tsuba and other fitting would have been periodically touched up.

Hi Glen I can't claim any credit for correcting the Silver sulphate typo, I didn't see it at all I was only focussed on the black stuff Your explanation that silver sulphide forms a "network solid' is actually further helpful in going someway to explaining how this conversion actually migrates away from the source silver as on the tsuba you show. I wonder if this is a sort of flowing structure? It does actually come away from the iron ground very easily so It doesn't seem to be significantly bonded at that point of contact. The silver sulphide on the actual silver, on the other hand, is quite strongly bonded. I tend not to use any sort of abrasive methods it removing it, because of the delicacy of the work mostly, so I use a chemical solution to break down the sulphide that is very gentle in its action. I won't mention what it is for fear of unleashing DIY restoration armageddon.

Colin, those latest images are really far more revealing. I can see what you mean with respect to there perhaps being some indication of structure in the iron. If you'd like to send it to me, I'm in Dartmouth, I'll remove all of the rust/corrosion product safely, photograph at high magnification and resolution the resulting surface and then re-apply a suitable patina. I'll do this for free and post the images here so we can all see and learn more, and you'll get a much better tsuba back to boot. If you'd like to take up my offer message me for my studio address etc. And having read with interest the superbly detailed chemical and metallurgical discussions this thread has engendered I must add one last bit of info myself. As I think we've now established, and contrary to Bavarian school of metallurgy dogma , silver does indeed covert to a corrosion product, namely silver sulphide. What I'd like to add is some real world experience that is directly relevant to tosogu and may be of interest to fellow students of the art. As a restorer I must have worked on at least a couple of dozen of bronze vases that featured fine silver wire inlay. Typically the wire was around 0.5 mm in diameter and once inlaid it had been polished flat. These were mostly Meiji period pieces so around the time I worked on them perhaps 90 to 100 years old at most. Without exception the silver wire was black, unless someone had previously buggered around with them in which case the bronze patina was knackered too. Sometimes the black 'scale' (silver sulphide) had grown so thick that it'd started to flake off. This flaking happens because the silver sulphide is very brittle compared to the underlying silver. Changes in temperature and the resulting differing degrees of expansion and contraction of the silver and sulphide layer causes a break where they interface. The newly revealed fresh silver appears a dull white at this point and is quite rough in appearance, almost stony. It's quite a fiddly and time consuming process to restore a degree of polish to this corroded silver. With the silver sulphide removed what was once a smoothly polished surface now has a very clear groove in it that you can actually catch your finger nail in. Consider that the wire was 0.5 to begin with ( an average based on those pieces I've restored and had to re-inlay) , some thickness is lost in the inlay and polishing process so we can estimate perhaps a depth of around 0.35 remaining. this is in fact what I've measured myself when dealing with tiny fragments that have fallen out. What is remarkable is that the action of the hydrogen sulphide in the air in converting the pure silver (it's almost always fine/pure silver in Japanese inlay work) into silver sulphide has easily consumed half or more of the original silver in 100 years. Sometimes actually all of it. This is also why we find that gold nunome-zogan tends to survive more frequently than silver numome-zogan. Even on the same piece of work the silver will inevitably be more fugitive compared to the gold. This is a very real problem I've had to deal with countless times. Higo tsuba collectors will know this well too I suspect, tea inspired wabi-sabi aside those Jingo tsuba rarely have much silver left. Some applies to Hizen and Jakushi works. For reference the foil used in this type of Edo period nunome-zogan is generally around 0.02mm thick, that's about as thick as a sheet of standard 100 gsm printer paper or 20 microns thick. In the Jewellery industry the accepted standards for gold plating is 0.5 microns (or more) for standard plating and 2.5 microns for heavy (sometimes termed Vermeil, from the French term for mercury gilded bronze) plating. And 20 microns of fine/pure silver (jun gin) sometimes doesn't last 100 years on a tsuba whereas gold that thin can survive in wet acidic soil for thousands of years virtually untouched. Well, the gold survives, naturally, but any additional copper or silver in the alloy is inevitably attacked and is lost to the gold artefact. This leaching out of the non-gold elements is what causes that characteristic frosted rich fine gold appearance of ancient archeological gold.

I've been bothered by this muddying of the waters regarding corrosion and rusting. The actual physical and chemical process whereby iron and steels is converted into any of the corrosion products I listed as 'rusts' in my previous post is called, by real metallurgical scientists, the corrosion process. We can have our own, tsuba/tosogu specific understandings of patina etc. and personally I need to make that distinction sometimes because that's a big part of my own particular work. But : The action on the metal is 'the corrosion process' and the result of this process is 'the corrosion product' or rust. Sometimes this rust can be made into a stable and attractive finish we enjoy as patina.

I didn't suggest they were interchangeable at all. Nice summation of exactly what I wrote; "Corrosion in fact covers the damage caused by rust, and that's really what we're looking at here. It is perfectly correct to speak technically about a corroded steel structure and to distinguish it from a merely rusted one." On zinc and lead it'll be white. Silver is reduced to a black silver sulphide, as described below. The corrosion products that occur on iron and steels appears in a range of reddish, brown to black colours and is known as rust. Some of the blue and green corrosion products you refer to do contain some oxygen but those particular compounds are generally more complex than simple copper tin zinc lead alloys and oxygen. Copper chloride is a turquoise colour CuCl2, no oxidation involved. Copper Nitrate is a good royal blue, if it was only oxygen doing the work the result would be either black or brick red but the nitrogen changes things. Cu(NO3)2 Not all corrosion is in fact a result of oxidisation, as described above. Take silver as an example pertinent to tosogu, it's a silver sulphide Ag2S that forms on the surface and gradually consumes it. I ought to add that the broader topic of corrosion covers much more than only metals and involves many more complex process other than merely oxidisation. The scientific literature on rust lists (at least); 12 varieties of Iron oxides and hydroxides 3 varieties of iron carbonates 9 types of Iron chloride 12 Iron sulphates 4 Iron phosphates and 10 Iron carboxylates and cyanides. These all have their own particular colours and microscopic structures. The colours range from yellows, ochre, green, a wide range of browns through to red, greys and black. I believe it's the interplay of various specific 'rusts' like these, in a patina, that results in the characteristic colour and tone of certain Tanko school's tsuba. What has been especially interesting to me is that traditional tsuba patina recipes and those I've developed from the original sources reflect very well almost all of those varied and complex compounds we generally lump under the generic term 'rust'. Rust is so so much more than Iron oxides. Stable iron patina are invariably complex and multi layered compound structures produced by complex and sophisticated process that were developed over many generations through trial and error. If it just looks like crusty red iron oxide the patina is long gone. Well that'll teach me to throw in my tuppence worth... but as chance would have it I was in fact writing on exactly this topic of corrosion and ferrous patina last evening.

Alban, this is a superb piece, I can see why you love it.

thank you Brian, for your endorsement. in case my meaning was unclear due to my typing error; 'Despite apparent serious surface corrosion there is the evidence of laminar structure that would inevitably be present in hand wrought pre-industrial steel/iron.' ought to read Despite apparent serious surface corrosion where is the evidence of laminar structure that would inevitably be present in hand wrought pre-industrial steel/iron? Dan, I'd have to disagree with your suggestion that this is a rusted, not a corroded, piece of material. Corrosion in fact covers the damage caused by rust, and that's really what we're looking at here. It is perfectly correct to speak technically about a corroded steel structure and to distinguish it from a merely rusted one. Structures made from Corten steel, for example, rely on the formation of a rust coating to protect it from further rust penetration that would lead to corrosion and mechanical failure. Perhaps a simple and more familiar example might clarify; the patina we admire on ferrous tsuba are composed of rust, albeit in a fine and stable state. Once that stable rust patina is disrupted and 'goes live' it is actively rusting, and causing corrosion, ie; the degradation and breakdown of the metal's surface and eventually structure. As for the time it might take for a surface of steel or iron to exhibit the sort of texture this example shows that would depend entirely on the conditions it was kept in or subjected to. It's perfectly simple to recreate this degree of 'apparent' corrosion in a few months. Quicker if you were to use a little bit of electrical current to speed things up a bit. And for anyone who really wants to go down the rabbit hole of pre-industrial ferrous metal structure and the effects of time and corrosion etc. these four books are the most frequently thumbed on the subject in my library. There's about 1300 pages of solid material in there. regards all Ford IMG_0990.HEIC IMG_0992.HEIC

For what it's worth this is what I see... Despite apparent serious surface corrosion there is the evidence of laminar structure that would inevitably be present in hand wrought pre-industrial steel/iron. This sugests that the tsuba is made from an homogeneous plate of material, my intuition suggests mild steel. The second point, already implied by my first observation, it that the very evident pock-marked corrosion surface is absent from the inner walls of the sukashi. We also see still crisp edges around the seppa-dai and, for me, unconvincing tapering out of the texture in to the seppa-dai itself. The kozuka atari is a bit too curved too to be a reasonable fit alongside a kozuka back suggesting a lack of awareness of its realy practical function and meaning. My feeling is that this is a modern-ish hobby piece worked up to look older than it really is.