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UltravioletPhotography

Chinese Cloisonné Artifacts - a VIS/UV comparison


igoriginal

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A brief overview, and some abridged history

 

In recent months, I've been hard at work with experimenting along "roads less traveled", with regards to VIS/UV comparative imaging. That is to say, applying creative thinking in selecting subjects which are non-conventional in such a process. (I can take VIS/UV comparative photos of only so many flowers, until my interest begins to stagnate and waver).

 

While in the process of this redoubled effort in getting my creative juices flowing again, I was hit with a pang of inspiration to turn my UV/VIS pursuits towards various artifacts and trinkets which I have been collecting over the years.

 

In this case, what we have here are a few colorful specimens of Chinese cloisonné artifacts.

 

For those who are uninformed on the art of cloisonné-making, it originated as an ancient craftsman practice of externally decorating a metalworking object with a faceted, multi-colored overlay (usually used on pottery, jars, jewelry, weapon hilts, goblets, and other trinkets) that dates as far back as the Byzantine Empire period (the Eastern-divided half of the prior greater Greco-Roman Empire, a period which began at around 330 C.E. and ended around the middle 1400's).

 

The reason that the terminology for this art-form is derived from the French word - "cloison" (which means "partition" or "divider") - is because this skill-set involves an arduous and tedious process of bonding (and in more modern times, soldering) a intricate pattern of metal filaments (which form shallow compartments) onto the metal-worked object, to then be used as the borders between later adding multi-colored enamel material (soft and pliable, at first); ultimately with the goal of designing fanciful facets separated by the filament lines. This is finalized by kiln-baking the finished object to harden the added components so that the resulting work is one solid object which in many cases is reminiscent of a "stain-glass window."

 

The initially soft and workable translucent enamel composite material for filling in those gaps between the dividing filaments was often a clay-like blend created by mixing metal-oxide powders of varying colors (grinded away from raw ores) with silicate-based powders (pounded and grinded away by using sand), then further mixing into a glue-like resin material. When cured in high enough heat, the finished product becomes hardened, semi-lustrous, smooth, and permanently fixed in place.

 

(NOTE: Byzantine-era designs implemented facets of gemstones, in some cases, rather than the more common use of enamel, especially when it was dedicated towards those of nobility/royal status, upper-level clergy, or of prominant political hierarchy.)

 

The underlying metal shape of the workable object, itself (before the cloisonné artwork was added to its surface), was often of "gilded" metalworking properties, created by physically pounding a more stable base metal (commonly an alloy of cropper such as bronze) with a softer and more lustrous metal (thin gold leaf, for instance), which resulted in a gilt-metal work. This especially became the more prevailing common tradition of the cloisonné-making process of medieval-era Chinese culture, once this skill-set was spread by traveling merchants beyond the Roman empire and onward into the Persian territories as well as the greater Indo-Asian subcontinent.

 

Cloisonné metalworking still remains popular, today (especially in the Orient as well as in the Middle East), although the thin layer of gold alloy (or silver, or a mixture of the two, plus other metals) is now electroplated instead of mechanically pounded into the base metal, given that such a modernized process is obviously more efficient for mass-production industry.

 

 

The quick test (my very first one)

 

When I was hit with the inspiration to turn my VIS/UV comparative photography towards some of my ongoing collection of such metalwork, I was in for some startling results!

 

While I knew that the comparison imagery would be a fascinating experiment, I never imagined that the types of colored metal-oxide powders used in the creation of the glass/metal-conposite facets would yield such wildly varying UV-absorptive and UV-reflective properties!

 

Apparently, some metal-oxide/glass-mixed enamel substrates absorb a lot of UV, others reflect a lot of UV, and others still exhibit a varying level of both. This is very surprising, indeed, and it is quite stunning!

 

 

Equipment used

 

~ Camera: Panasonic Lumix GF3; Full-spectrum-modified; Use of additional loop-based viewfinder/eyepiece accessory attached to the rear LCD screen, to help with magnified and detailed focusing while eliminating stray light.

 

~ Lens: Custom-made 20mm F/4 UV-capable lens (becoming 40mm F/4, on the 2x crop-sensor of a Micro-4/3 camera).

 

~ Optical filters(s): 1.5mm-thick ZWB1 (UV-pass), 2.5mm-thick BG39 (IR-block).

 

~ Flash: Vivitar HV285; Full-spectrum-modified. Used off-camera, no electronic contact with camera body (by hand, manually), through the process of multiple-flash actuations from various angles during long exposure (for UV-only image), in order to illuminate the subject more consistently and reduce strong shadows.

 

 

Results

 

1. Medium azure-blue colored enamel facets in VISIBLE imaging exhibited a light lavender or light periwinkle color in UV-A imaging (neutral white-balanced).

 

2. Light rose-pink colored enamel facets in VISIBLE imaging also exhibited a very bright/off-white color (nearly fully UV-reflective) in UV-A imaging (neutral white-balanced).

 

3. Light cyan colored enamel facets in VISIBLE imaging exhibited a dark indigo color in UV-A imaging (neutral white-balanced).

 

4. Lime-green and dark red colored enamel facets in VISIBLE imaging exhibited nearly fully UV-absorptive properties (very dark, near black) in UV-A imaging (neutral white-balanced).

 

5. Black colored enamel facets in VISIBLE imaging exhibited a slightly more reflective (very dark grey) color in UV-A imaging (neutral white-balanced). The overall spectral response remains primarily UV-absorptive, however.

 

6. The gold-powdered electroplated paint layer (very likely a cheaply-sourced, low-quality gold mixed with another metals, such as copper and/or silver, and not a 24-karat gold) over the bronze base of the metalwork in VISIBLE imaging exhibited a generally neutral (grey) spectral response in UV-A imaging, demonstrating that it reflects an even amount of narrow-band activity ("flat" reflectance response) across the entire UV-A range. However, it appears to render some specular highlights in some places that are biased towards a yellow-greenish tint (seen as a subtle olive-colored hue), especially in spots where the flash from the UV-modified flash gun (a Vivitar 285HV) struck at highly-reflective angles.

 

 

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Very interesting--I notice that one of the floral(?) motifs on the left-hand vase has "nectar-guide" patterns appearing only in the UV! It would be interesting to reprocess this image pair into a GBU composite.

 

(I also notice that the varnish on the underlying table is rather UV-opaque.)

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Very interesting--I notice that one of the floral(?) motifs on the left-hand vase has "nectar-guide" patterns appearing only in the UV! It would be interesting to reprocess this image pair into a GBU composite.

 

(I also notice that the varnish on the underlying table is rather UV-opaque.)

 

That is interesting, isn't it? That the choice of enamel layering in the lotus flower ended up mimicking a suggested "nectar guide" pattern. I am certain that this was purely coincidental, of course, but it's amusing that it happened to fall into the hands of a person who decided to give it a UV/VIS test and is aware of such patterns in nature.

 

Of course, the actual chemistry responsible for this artificially-induced "nectar guide" (even though accidental and unintended of its "hidden" effects in UV photography) is due to the deliberate crafts-work of shifting the variability in the metal-oxide blending within the enamel substrate along the length of the petal, in order to elicit a subtle shift in the visible coloration of the petals. (If you look more closely, the center of the lotus flower is a visibly off-white with only a small hint of color, but there is a gradual shift towards stronger cyan colors as you move away from the center and towards the tips of the petals).

 

It really is humorous, though, how it turned out to unwittingly mimic a would-be "nectar guide" when viewed under a UV-only image. :D

 

By the way: That's not a table. That's a floor. But the varnish effects (highly UV-absorptive) are notable, just the same.

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Very pretty in both spectra! My grandmother has a lot of this around. I may experiment also.

 

These little trinkets really are a delight to the eyes, aren't they? And Ebay is actually littered with them, be it more dated (pre-modern) and prohibitively pricey specimens, or the more recent and cheaply mass-produced varieties. My own items are most likely leaning towards the latter. I date them to be about post 1940's, but pre-Chinese market-flooding era of today. Well, the items on the left and right are decades old. But the one in the center is a freshly-made and recent item. Even so, the process of making these probably hasn't changed much in the use of the basic materials (for the past century, that is). What has mostly changed is the technology implemented in their mass production.

 

However, there are such artifacts (true relics) that date back hundreds of years (in some cases, nearly a thousand years), and those pre-Industrial Revolution cloisonné works would be interesting to compare under a UV exposure, compared to these more modern offerings, because the materials used in their construction were undoubtably formulated in a significantly different manner than what I have in my possession. (I am even wondering if UV imaging can be used to determine their approximate era of design, because of this).

 

But, I am no cloisonné expert.

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Igor, welcome back & a good find.

Col

 

Thank you, my friend! Yes, it is nice to be back. I hope all is well with you, these days.

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Very interesting.

 

I really like seeing this kind of UV investigation.

 

Thanks, Andrea.

 

Speaking of "investigative work", when I was creating this post, I had the intention to produce the info in a more "formal" structure (note the way I presented the information above, divided by sections, including a brief history of the subject, and also neatly itemizing the results in a numbered summary). However, I notice that this site does not have any options for non-living items to be presented as formal posts. There are existing options for flora, fauna, and other botanicals, of course. But perhaps we should consider adding a formal section for "non-biological objects" or something along those lines? (And perhaps also sub-categories, such as "trinkets / artifacts / relics", for instance?)

 

I can tell you this: I will now endeavor to work with doing VIS/UV comparisons of additional trinkets / artifacts / relics, and to post formal-like results on UVP on my finds. (Of course, in the meantime, I will be going through the "informal" zone to do this). Not just exclusively Chinese cloisonné, but artistically-worked pottery/jars/vases from other cultures, styles, eras, as well. I have a feeling that there are some startling finds to be made, there. And I even have a hunch that due to my initial experiment into this era, such testing can be used to reveal certain forensic attributes/properties that can be useful in some regards, perhaps? (To anyone visiting this site and going through its archives).

 

Anyway, just some thoughts from the top of my head. :rolleyes:

 

I hope that you have been doing well, by the way, and all is good on your end.

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Thanks, Igor. All is well. :)

 


 

Originally I had intended the Forensics section for this kind of thing.

But a non-botanical, formal section seems reasonable.

I'll put it on the list to look at this week.

 

You would need to add formal references about cloisonné. Preferably not from internet links. Although these days we have all become more lenient about Wikipedia links because they have worked hard to clean up things. And links to specialist groups or societies which have an online presence are sometimes OK too.

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Thanks, Igor. All is well. :)

 


 

Originally I had intended the Forensics section for this kind of thing.

But a non-botanical, formal section seems reasonable.

I'll put it on the list to look at this week.

 

You would need to add formal references about cloisonné. Preferably not from internet links. Although these days we have all become more lenient about Wikipedia links because they have worked hard to clean up things. And links to specialist groups or societies which have an online presence are sometimes OK too.

 

Thank you for your consideration on such a section proposal.

 

I have been building up a database of various resources on such matters. They are web-based, however, the links which I am gathering are in reference to actual scholarly consensus, rather than loosely-held and under-trained mere pop-culture opinions. I definitely agree that we have to maintain a certain level of scientific standards, whether it be in the areas of biological subjects, or non-biological subjects.

 

Thus, I wholeheartedly agree with you. Which is why I owe it to myself to more thoroughly educate myself on the areas of craftsmanship, such as metalworking, pottery, and other forms of man-made artisan creation. I started with cloisonné, because I felt that it presents a more immediately rewarding and stunning exploration through multi-spectral imaging, given the fact that the workmanship involves many facets of various color and mineral/chemical composition, hence more likely to elicit a striking comparison in various spectra. This is not to say that I will limit myself to only cloisonné pottery and similar works, but in the meantime to focus and concentrate on a narrow area before moving on to anything else. Even as I type this, I have more cloisonné specimens on the way. In addition, I will be consulting with some of the merchants which I purchase these from, so I can gain more insight as to what regions of the world they are made, who makes them, what variability is there in the process of creation, and so on. In other words, it would help to develop some form of a standard for "origin of creation" as well as "era (dating) of creation", to better catalog these works.

 

I suppose I shall see just how far my endeavor takes me. In the meantime, I'll be trying to set up for additional photo comparisons to post on here, as more items come in. (Although I also still have existing items in my collection that I have yet to photograph and present). I should probably also consider selling back the majority of my subjects, after taking comparison images of what I acquire, because it's not like I have infinite storage space or financial resources. :)

 

EDIT: Last but not least, I also just realized that in order to make a truly formal presentation, I should not be photographing more than one subject together in the same batch of comparison images, such as within this post. Meaning, that of the three subjects above, two of them (on the left and right) are from an older period (1940's-1960's, approximate dating), whereas the one at center is dated as more recent (within just a few years of creation). Meaning, just as our botanical posts are based on one specified subject at a time (we do not mix two or more species of flowers into a single botanical post), so should the same convention be followed with these non-biological subjects, as well (one item at a time). Otherwise, keyword searches would become unreliable and convoluted.

 

Hence, when the time comes (should you indeed decide to create the pertinent section), I will have to re-do this first post of mine.

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I would think it is OK to have a survey article and a survey photograph which includes a range of Cloisonné specimens. Given that this is not a specialist site for collectibles, there is probably no need to be overly detailed. But that would be your choice. Granted the botanical section is detailed but the genus/species of a plant lends itself to that categorization. And also that was a special interest of the founding members. "-)

 

I'd try for one general write-up. And then if you maintain the interest, you could produce write-ups for one specific object at a time. You have to see how these things go.

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