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Inlay tutorial


Jim Kelso

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Whilst looking forward to Ford's nashiji, I'll post a bit of my own on a shibuichi(85%copper/15%silver) vase.

This as cast surface shows the graining to maximum advantage. Any project where you want this effect must be thinned(rolling or forging) as little as possible. On this piece you can see(along with the dust particles :D ) areas of general finer grain and areas of larger crystaline formations, some of which can be seen in the field above the peony.

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Guest ford hallam

these two images (of the same piece of metal) will hopefully illustrate what I'm describing.

 

Actually Jim, the effect you see on your cast shibuichi vase is called "kesho" in Japanese. It's the dendritic structure that invariably occurs in "as cast" objects. It's a result of the rapid cooling and consequent shrinking of the molten metal. If you recall, a while ago, Garret McCormack posted some images of an ingot he'd cast and then forged down to make a tsuba. I commented on exactly this aspect of his piece at the time. This dendritic structure can often be seen in cast ingots of practically any of the cuprous alloys and of course copper itself. Incidentally, the term "kesho" is also applied to the fairly large crystalline structure seen in Sentoku alloys.

 

Nashiji is a completely different phenomena, whereas dendritic structure is generally broken down in the forging process when making sheet metal, true nashiji always remains visible. If you are finding that you have to keep the processing of the cast metal to a minimum in order to retain the apparent nashiji effect then the chances are that the metal was held at liquidus too long and the silver molecules have dissipated too much.

 

The piece posted below was cast as a hamburger type pattie into hot water and was forged down from about 12mm. It is now a tad under 1mm.

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Hi,

It's amazing how much misinformation we get in college classrooms. When I was taking metal working in undergraduate, graduate and even post graduate courses I was always taught to quench the metal after heating to a bright red to anneal it for rolling. I often had trouble with the metal cracking. I also taught students the same thing. Fortunately I had a friend who was a professional goldsmith who made all of his gold sheet stock who had been through the apprentice system and had not studied art in college. He showed me how to not over heat the metal and to let it air cool slowly! I sure wish TCP existed back then but of course back then the only computers were the size of tractor trailers. Thanks to craftsmen like Jim and Ford those mistakes can be avoided. Thanks guys!

Dick

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Guest ford hallam

this is an example of the effect called Kesho. You'll notice some areas of quite distinct and large crystals and other areas, notably above the head of the dog, where the structure is so fine as too appear as if it is grained. Sorry about the poor quality of the image, yet another scanned photo :( .

 

Hi Dick,

 

my comment about air cooling in this instance was specifically for shibuichi alloys. There are actually some alloys that do need to be quenched while still relatively hot, though red hot is probably a little extreme. :D You can however, forge copper and fine silver while red hot. You do tend to get lots of blisters though! :D

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Aloha Ford, Jim et al

 

Just taking a quick break to check on my query. Fascinating stuff. It actually answers questions on many levels.

Earlier attemps at alloy casting produced what appeared to be very large crystals (1-5mm). The literature indicates that this all needed to be broken up by forging.

My wife took some scanning electron micrographs which showed a very interesting "beehive?" structure. (It is difficult to understand how the alloy can hold together cohesively, yet distinctly through all the compression and stretching.) Ford's explanation helps me understand what I was looking at. I thought this was bad, and considered recasting as Peter had. Ironically, as I better comprehend the "micro" I will need to train my eye to recognize the "macro". I guess patina trials will tell the tale. Keep good notes!

If anyone is interested, I can try to post the EM images.

 

mahalo

Karl

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Guest ford hallam

Aloha, Karl,

 

glad to have shed some light...I for one would very much like to see these images you mentioned. :D

 

Hi Jim,

 

You are absolutely right, the fine grainy structure you see on the "as cast"surface is very similar to what I consider to be true nashiji ( if I can be so specific ). My observations and research would lead me to see it as something slightly different from nashiji though. The fine graining on your vase, even though it is a shibuichi alloy has the same sort of grain appearance I've seen on other non-shibuichi castings.

 

Nashiji actually has a very specific microscopic structure quite distinct from fine "as cast" grain structure. I'll post some micro-pictographs tomorrow which will clearly illustrate the difference. As I mentioned previously, If the alloy is at liquidus too long the specific "moment" that nashiji can still be discerned is lost and the alloy loses it's unique characteristic. This is also why, if you remelt shibuichi you must always add at least half ( by volume) of new alloy ingredients. Otherwise you get a straight flat colour and no grain.

 

cheers, Ford :D

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Jim and Ford- thanks very much for those close-up photos and information. While the technical aspects of creating these alloys will probably not be retained in my head, I have a better idea of what I used to think of as just 'granulation', next time I see it in a museum or collection context.

 

-D

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Thanks Jim, & Ford for this facinating look at this subject - I am only just beginning this process, but I can appreciate the subtlety. Karl, I'd also like to see the EMphotos you spoke of. I just got my copy of Untracht's book in the mail yesterday- it's helping me relate more to some of this.

Thanks again to all of you,

Magnus

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Aloha Ford,

 

Apologies for any delays; I had to wait the brains of this outfit (my wife Tina) to set me up.

These images are of my first "mix"; 40% silver/ 60% copper derived from sterling scraps (I know, I know) and copper electrical wire. It was melted in a Kerr electro-furnace and poured into a carbonized, stand up ingot mold. The first image is a scanning electron micrograph of the as cast surface. The second shows a backscattered electron image with the silver as the brighter matrix and the darker copper as islands.

I am going to make a leap of intuition and guess that the principle of nashiji is that the copper reacts to patinas while the silver does not. The more silver added, the smaller (or less) copper exposed, the more delicate or ghost like the effect and vice versa.

Thanks for taking the time to go through this.

 

mahalo

Karlpost-1054-1175334899.jpg post-1054-1175334924.jpg

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Guest ford hallam

Hi there Karl,

 

those are fantastic pictures, especially the "stonewall" image. It shows perfectly what I was trying to describe. The other image show a wonderful degree of detail of the copper aggregates, you mentioned that this is the "as cast surface, I would suggest that the slightly "fern-like' copper structures are varieties of dendritic structure we were discussing earlier. The structure we can see very nicely on the right hand image is known as "Hyper-eutectic", it refers specifically to the silver eutectic network surrounding the copper particles.

 

Interestingly you can see tiny voids in the example on the left, the black bits. These are potential fracture points. When melting pure copper or silver it is vital to maintain a reduced ( ie; oxygen free ) atmosphere. Both these metals have a propensity to absorb a lot of oxygen when molten. The oxygen forms oxides within the alloy as well as resulting in these tiny voids of trapped gas. This is probably the most common cause of flaws in these alloys. This is one of the reasons that I often follow the old method of casting my ingots into boiling water, it limits the absorption of oxygen into the surface as the metal cools and solidifies. I also pack a layer of charcoal on top of the metal in the crucible, this tends to absorb any free oxygen that may sneak in. :D

 

Your intuition is spot on with regard to the colouring of these alloys too. It's actually cuprite that forms on the copper ( Cu2O ) while the silver remains unchanged. Actually there are ways to get the silver to colour too, this extends the possibilities a bit. It is also why shibuichi changes colour over time, more so than most other traditional alloys. There is still another very specific process that must be applied to finally achieve the characteristic velvety finish often seen on the best pieces. This is quite a complicated thing to explain, though less so to actually do. I will describe this in detail on my site in a little while. One of those images of yours would be helpful in describing the process actually :(

 

Cheers, Ford :D

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Aloha Ford,

 

Once more, you have lifted the veil of ignorance. I often wondered why the ancient method of water casting produced what is described as a purer form. Gene Pijanowski has told me that it takes some practice to get all the variables right.

The images are courtesy of my wife Tina. She has helped out authors such as Tim McCreight in the past. I'm sure something can be worked out.

Your sharing spirit is beyond generous. I hope you don't use up that bag of knowledge (allusion to Hotei). Save some for that future publication. We will all get it anyway.

 

mahalo

Karl

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Guest ford hallam

These are some microphotographs of classic eutectic structure (Nashiji) in Shibuichi. These images were produced by Dr Masahiro Kitada of the Hitachi Central Laboratory Co. the two images on the right, in B&W, are of antique pieces. All 3 micro-photographs are to the same scale.

The first image ( from the left ) is of an unworked, as cast,plate. The second, is of a low silver worked sheet and the last, a high silver worked sheet.

The similarity with the image I posted earlier, of a piece of plate I made and patinated, and the last image here is obvious.

 

And Aloha Karl,

 

You are more than welcome, I'm always happy to pass on what I can to anyone who knows what to ask? I hope what I've written will be of help, both to you and anyone elso who is intrigued enough to begin working with these facinating compostitions. Of course, the technical aspect is only just the very beginning, it's really what you do with the stuff that is the really exciting part. :D

 

you know how to reach me if I can be of any further help. I think my sack will be OK :D

 

regards, Ford

 

p.s. I seem to remember my teacher, Izumi Koshiro, mentioning that he remembered instructing both Hiroko and Jean Pijanowski many years ago. I'd be interested to hear if Mr Pijanowski remembers.

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Guest ford hallam

These two images show a micro-photograph of a plate of shibuichi which was carved and inlaid by the Meiji period Imperial artist, Unno Shomin. The structure is a classic, worked, eutectic surface, and is subtly frosted. The apparent matt ( frosted ) surface is an aspect of this phenomena. The colour image is a more recognisable view of this panel by Shomin. The panel is in the Museum of Tokyo National University of Fine Arts & Music.

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Aloha Ford,

 

More fantastic material. My head is spinning.

Answers lead to questions (don't they always?). Eutectic bond>mokume gane. Depth of strucure (is beauty more than skin deep?). Commercial suppliers; does their product meet an increasing sophistication of users?

I fear that I may have strayed us off Jim's tutorial on technique and into a materials discussion (Sorry Jim).

I briefly retire to digest this info and consider the practical applications.

 

mahalo

Karl

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Hello Karl,

 

Nashiji in shibuichi is a particular macro, as opposed to microscopic, grain structure that is sometimes visible with the naked eye on the surface of polished and patinated shibuichi. It occurs when the silver content has not entirely diffused throughout the copper matrix to form a true alloy. The copper molecules at this stage are still discrete clusters which are more or less evenly distributed. Think of raisins in a cake :D or think of the silver as mortar between the clumps of copper. When the alloy is finished "correctly" (?) it appears that the metal has a graininess to it. It is similar to the lacquer effect, just a bit finer. Nashi; are Japanese pears and they have a grainy patterning on the skin, Ji; means ground or surface.

 

Hope this helps.

 

Ford

 

This to me is the main point: that nashiji is a visual, human scale effect suggestive of pear skin. Surely, as Ford has shown, forging(or rolling) has an effect on the structure microscopically and hence, the appearance to the unaided eye. In a cast piece which has no need to be forged, the structure remains as cast. I would say that either way, if there is a graining, visible to the naked eye, reminiscent of a pear skin, then you have nashiji. The visual beauty of any given piece must be judged on it's particular merits. These are after all, visual works of art, and in my opinion should be judged as such, not on the basis of whether they conform to some process. Also, in my opinion, surprises and anomalies that don't conform to a general or particular set of standards should not necessarily be discounted out of hand. Human based standards are just that: someone making a judgment that their idea is correct. More important to me is the joy of discovery. Certainly standards have their place, but are they for our use, or we theirs.

 

I'm attaching two closer views of the vase shown earlier. One shows what I would certainly call nashiji in a fairly even distribution. The other shows nashiji along with the previously mentioned kesho dendrites. I magnified them to the point beyond which pixelation would start to confuse. I'm guessing that it's a 10-15 power magnification. I could figure that out but it's late. :D

 

 

I fear that I may have strayed us off Jim's tutorial on technique and into a materials discussion (Sorry Jim).

 

mahalo

Karl

 

No need to apologise. It's all part of the mix. Always something new and mysterious. :(

 

Jim

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Guest ford hallam

These two samples; the crow design is flat inlay while the other is raised, show 3 different shibuichi alloys. All the colours were patinated in the same solution. The darkest grey is 16% silver, the middle grey is 30% and the lightest, the crescent moon, is 60% silver. I imagine that Jim's waterfall will perhaps exhibit a similar tonal variation. What compositions are you using Jim?

 

The other image is of a few samples of various alloys in my "palette" tray. The odd one out has a very interesting structure which only became visible after patination. ( The pink/red and black one ) no silver in that one at all! :D it's one of my "unique" mixes! :D

 

Jim,

 

looking at these images you've posted it does indeed appear as though your vase exhibits nashiji. To be fair, I don't think it is for me to cast any sort of "final judgement" on the matter. Apologies if I seemed to suggest that your material was in some way "deficient". I was merely trying to express a certain degree of precision with regard to Japanese metalworking technology. Ultimately, if terms lose their precision then they become meaningless.

 

There was never any suggestion of dismissing anything out of hand. :( Your comment about works of art being judged on their merit, leads me to believe that somehow you think my remarks about the presence or absence of nashiji in your vase was somehow a criticism of its artistic qualities. That isn't what this thread was about at all. Sorry if you felt that way though. :(

 

at this rate this thread could become the definitive statement on Shibuichi on the web. :)

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Jim,

 

There was never any suggestion of dismissing anything out of hand. :D Your comment about works of art being judged on their merit, leads me to believe that somehow you think my remarks about the presence or absence of nashiji in your vase was somehow a criticism of its artistic qualities. That isn't what this thread was about at all. Sorry if you felt that way though. :D

 

My comments were intended more in a general sense, about finding a balance between precise technology and spontaneity.

 

I very much appreciate all the useful information. Thanks.

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Aloha one and all,

 

I want to thank Jim Kelso and Ford Hallam for a lively and informative discussion. mahalo nui loa

 

The process of discovery and understanding can be arduous; I watched (and participated) it happen many times in research labs I once worked in. The payoff is we all move forward. (Interesting, what a bunch of guys standing around a pit fire 300 or so years ago started.)

 

Lessons learned:

Don't stand around BSng with the next guy while your mix cooks to oblivion. Pay attention. Have purpose. Keep good notes.

Accept what the fire gods give you. Serendipity is part of the process.

 

mahalo

Karl

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