JAIC 1980, Volume 19, Number 2, Article 7 (pp. 106 to 111)
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Journal of the American Institute for Conservation
JAIC 1980, Volume 19, Number 2, Article 7 (pp. 106 to 111)


Heather Lechtman

Ars Orientalis Vol. 11 (1979), Memorial Volume to Rutherford John Gettens, guesteditorsElisabeth WestFitzHugh, W. T.Chase, ThomasLawton, JohnWinter, Lynda A.Zycherman, Freer Gallery of Art,Washington D. C.328 pp.

This is a splendid volume. John Gettens would have loved it, and it is a fine tribute to him. The contributed articles have been grouped into three categories: Paintings, pigments and lacquer (4 articles); Ceramics and glass (3 articles); and Metals (8 articles). All, of course, deal with objects from the Orient, primarily from eastern Asia but occasionally from Persia and other Islamic nations. Only 2 of the 15 articles have to do with conservation and preservation; the volume is primarily concerned with analyses of the materials comprising certain sets of artifacts and with the technical history of manufacture of such objects. The editors have conveniently assembled at the front of the volume abstracts of all the articles so that the reader can refer to these before delving further into the text. The book is handsomely printed and generously illustrated (in black and white) and is a bargain ($30.00) given the cost of publication these days.

The quality of the papers in this volume is uniformly high, and most describe the results of many years of research. Rather than present a brief, and, perforce, superficial summary of each article, I prefer to select for discussion a few from the two classes of materials on which Gettens concentrated his own investigations: pigment and metals.

The volume contains two articles on Japanese pigments, and they complement each other well. “Pigments Used in Japanese Paintings from the Protohistoric Period through the 19th Century,” by Kazuo Yamasaki and Yoshimichi Emoto presents an interesting review of pigments used on many kinds of object—tomb and wall paintings, screens and sliding doors, lacquer ware, scrolls—throughout the prehistoric and historic periods (roughly from the 7th c. B.C. to the 17th c. A.D.). Changes in the materials of grounds and pigments are discussed chronologically, and an excellent summary is provided of the characteristics of Japanese pigments, grouped by color. Two of the most interesting shifts in the use of certain pigments that have been found by the authors through their technical examinations occurred in the whites and blues. Until the 15th century, clay was always used as the white pigment for paintings. Between the 15th and 16th centuries, powdered oyster shell took the place of clay and continued to be used throughout the Momoyama and Edo periods until today (although the authors do not explain the reasons for this remarkable change). In fact, Japan seems to be the only country that has used oyster shell as a white pigment. The authors have also found that in small, precious paintings such as the hand scrolls of the 8th and 12th centuries (including the famous Tale of Genji) more expensive pigments were used such as lead white and organic coloring materials (e.g. gamboge). As for the blues, azurite has been used most often throughout Japanese history as the primary blue pigment except for a peculiar shift that occurred between the 9th and 11th centuries. At this time, a blue was achieved by dyeing yellow ochre with indigo. After the 12th century, azurite resumed its importance. Apparently the authors cannot account for this peculiar change, but they discovered it through technical studies. It is not mentioned in any of the documents of the period concerning pigments.

An interesting observation made by the authors is that the hanging scrolls and folding screen paintings of the Edo period (17th c.) that are known for their elegance and sumptuous use of materials have not yet been studied technically in Japan, yet there is a rich literature of 17th c. Japanese books on Edo painting techniques. Thus an article by Gettens, published in 1976, and Elisabeth West FitzHugh's contribution in the present volume, “A Pigment Census of Japanese Ukiyo-e Paintings in the Feer Gallery of Art,” constitute two important sources of information for this period. The FitzHugh article presents a detailed study of pigments used in Ukiyo-e paintings (paintings depicting the everyday life of ordinary people) which first appeared in the late 16th c. in the Momoyama period and continued into the very early years of the 19th c., the Meiji period. But this class of paintings is usually considered one of the schools of the Edo period when they were most abundantly produced. Ms. FitzHugh's study is particularly interesting because it pinpoints the palettes of several of the most famous of Japanese painters and print makers who produced Ukiyo-e—Hiroshige, Hokusai, Matabei. Shell white, vermilion, red lead, an organic yellow, and azurite were widely used by artists throughout this time span. By the 19th c., however, artists such as Hokusai used colors more sparingly than some of the earlier painters; thus a change in aesthetic style is reflected in their technical style which incorporated the more modest palette of the later years of Ukiyo-e works. The author presents an extremely valuable table of the pigments identified in 151 Ukiyo-e paintings studied at the Freer Gallery together with the analytical methods used in each identification.

John Gettens' last and perhaps most impressive publication was The Freer Chinese Bronzes, volume 2 of which, under his sole authorship, is devoted to technical studies of the Chinese bronze ceremonial vessels at the Freer Gallery. As the editors of Ars Orientalis 11 point out, “John Gettens' first published paper dealt with the restoration of bronzes from Iraq; it signalled the beginning of a lifetime interest in ancient bronzes, their fabrication, corrosion and treatment. The catalogue of the Chinese bronze ceremonial vessels in the Freer Gallery… represents the culmination of this aspect of his work” (p. viii). Though Gettens and other scholars—such as Noel Barnard and Cyril Stanley Smith—revolutionized our interpretation of the technological events surrounding the production of Chinese bronzes, fundamental questions remain that will be solved through a combination of technical studies and excavation of bronze foundry sites in China of Shang (1750–1100 B.C.) and Chou (1100–256 B.C) dates.

Barbara W. Keyser's article in the present volume, “Decor Replication in Two Late Chou Bronze Chien,” is an excellent case in point. She discusses the attention scholars have begun to pay to delineating the changes in casting techniques that accompanied the stylistic changes we see between Shang and Chou times. One of her interests is to explore the ways in which Chou founders extended certain aspects of Shang technical tradition while introducing new ways of dealing with ceramic molds and molten metal. The two late Chou (6th–5th c. B.C.) chien described in this article constitute an almost identical pair of vessels, important because they can be securely dated from their inscriptions and, “from the technical point of view, [they] provide an unusually clear opportunity to study the techniques by which late Chou founders used identical decor modules to construct the patterns and/or molds for casting a series of vessels” (p. 127). Most of this study is concerned with a) the identification of modular elements that were used by Chou founders to reproduce design motifs on a given vessel or on different vessels and b) an analysis of whether such designs were executed directly on a pattern or model of the vessel or whether they were incorporated, in the negative, on the surface of the ceramic mold into which the molten bronze was poured. The latter question has been a major issue among all scholars who have examined Chinese bronze castings.

In addition to the minutely detailed and impressive technical study of the two chien, the author has also brought to bear on her analysis the findings published by Chang Han, one of the principal excavators of the late Chou foundry site of Hou-ma (Southern Shansi), where Ms. Keyser believes the chien were manufactured. Hou-ma represents for late Chou studies what An-yang has meant for studies of Shang bronzes, both sites having yielded mold fragments used in production of bronzes at each foundry. The author explains that one modification of Chou casting technique, as compared with Shang practice, is a shift from placing decor primarily on the pattern and incising only details into the mold surface to decorating the mold surface directly. One factor that aided this change was the fineness of the mold material used at Hou-ma—in contrast with the coarser fabric at An-yang—which made possible the repeated transfer of subtle modelling from master pattern blocks without loss of detail. Taking all the evidence into careful consideration, her findings concerning this pair of chien are: 1) 2 complete molds were used to produce the vessels (not the same mold); 2) the decorative motifs were placed all around the vessels before the vertical mold divisions were made; 3) flat master pattern blocks were probably used to impress the motifs on strips of clay that were then set directly into the mold surfaces. Thus, of the two possible methods of manufacture that could have produced the chien, the author ultimately opts for direct decoration in the negative of the mold surfaces. “No simple pattern ever existed. The bronze caster did not start with a pattern … of the finished bronze, but rather began with the molds. … ‘Sectionalism’ occurs not in the mold itself, but in the decor replication techniques employed” (p. 161). Ms. Keyser is to be congratulated not only for a fascinating article but on having included in it the only map of the areas she discusses to be found in the entire volume! Authors and editors alike have been meticulous about preparing for the reader glossaries of technical terms in English, Chinese, and Japanese, but no one except Barbara Keyser deemed it necessary to show the reader where, geographically, sites, cities, provinces and people are located.

The article by W. T. Chase and Ursula Martius Franklin on “Early Chinese Black Mirrors and Pattern-Etched Weapons” is a state-of-the-art study and one which, again, builds upon early investigations (as early as 1934) by Gettens on the nature of the black, shiny surfaces characteristic of some Chou and Han (3rd c. B.C.–3rd c. A.D.) bronze mirrors. Chase and Franklin have taken the study of this peculiar black surface layer further than any previous investigators. Their article is a review of all pertinent literature on the subject, historical, art historical and technical, as well as a thorough discussion of their own technical findings.

It seems clear that from Middle Chou through Han times two types of mirror were produced, a shiny, “white” mirror of speculum metal (a copper-tin alloy containing ca. 25% Sn) and a black mirror, made of the same metal but whose surfaces were treated to turn them shiny black. Both black and non-black mirrors have been found in the same tombs, the black mirrors exhibiting unusual resistance to corrosion, whereas the others have developed the usual green corrosion products normal to high tin bronzes.

The authors have examined approximately 40 black mirrors over the course of many years. From these investigations, they present a picture of a “prototypical black mirror,”: 1) it is cast from an alloy containing ca. 70% Cu, 25% Sn, 5% Pb; 2) such a mirror was cast and cooled as were other, non-black mirrors and received no subsequent working or annealing; 3) after polishing, the surface of the mirror was sealed with a non-metallic layer that appears to be an amorphous silicate or mixed oxide containing iron and SiO2; 4) below the non-metallic layer the original bronze alloy is significantly altered, the α-phase replaced by an iron-containing compound while the δ-phase remains (the reverse of the usual manner in which tin bronzes corrode, the δ-phase being attacked and the α-phase left unaltered); 5) both the shiny surface layer and the altered zone beneath are enriched in tin and depleted in copper and both contain silicon and iron as major constituents; 6) the non-metallic surface layer is only lightly colored and transparent; the black coloration seems to arise from the altered zone seen through the transparent surface.

The authors deal with the possible uses for such black mirrors. For example, some documents cite their employ for collecting dew at night. Geographically, the black mirrors are often excavated within the ancient domain of Ch'u, and they spread throughout China during early Han times. All evidence leads to the conclusion that both shiny white and black mirrors were made and that the black color was intentional and is not the result of an unusual form of corrosion during burial.

To broaden their corpus of objects somewhat, the authors include a discussion of various types of late Chou pattern-etched bronze weapons. These were studied since they, too, exhibit intentional surface coloration produced by etching the bronze. In some of these cases, it is the δ-phase that has been attacked by corrosion mechanisms normal to such bronzes; in others the α-phase is altered in the same way as in the black mirrors.

The thorny question still remains as to just how the black, lustrous and apparently vitreous surface coatings were produced on these objects. One explanation suggested by the authors for production of the surface blackening (but not the glassy layer) is a prolonged etch in a reagent such as ferric chloride (prepared from rust with wine vinegar and salt). Ferric chloride will attack the α-phase of a high tin bronze and turn it brown. The authors realize, however, that only experimental attempts to reproduce the glassy surfaces they have so meticulously studied and characterized are likely to result in viable explanations for the phenomena we see. It may be that materials scientists studying the production of modern metallic glasses will turn their attention to this ancient metallic glass, especially since its ability to protect bronze in the presence of highly corrosive environments has been duly demonstrated during more than 2500 years.

The article ends with an attempt by the authors to relate the Chinese interest in surface treatments of bronzes to the overall cultural aesthetic of Late Chou and Han times. They point out that there was a significant change in that aesthetic from the late Shang and early Chou periods. “The early emphasis on size, forms which arise naturally from piece-mold casting, and surface decoration which emphasizes the mass and cast shapes of the vessel is replaced by an aesthetic of surface treatment and richness. The number of finishing techniques for metal increases greatly in scope and sophistication” (p. 256). Thanks are due to Chase and Franklin for putting their technical studies and the technological efforts of ancient Chinese metalworkers into some larger perspective. Not many of the articles in this volume do that.

The final article in Ars Orientalis 11, “The Techniques of the Japanese Tsuba-Maker” is a fitting closure to this tribute to John Gettens, for it emphasizes and reiterates the close association between the properties of materials and the forms dictated by cultural choice. As the authors Elaine I. Savage and Cyril Stanley Smith state, “The Japanese have been more sensitive than most peoples to the inner nature of materials and this underlies the distinctive character of their decorative art. The materials of the tea ceremony—ceramics, metal, stone, plaster, bamboo, lacquer and wood—all have subtle surface qualities that interact with and reinforce the overall aesthetic requirements of the form” (p. 291). Their article illustrates how these interactions are controlled and enhanced by the Japanese in producing tsuba (Japanese sword guards).

Most of the color and texture effects that are characteristic of tsuba result from the action of a suitable etchant upon the metal of which the sword guard is made. The latter may be a disc of forged iron or it may be a non-ferrous alloy such as brass orshibuichi (a copper-silver alloy). In many cases, the disc is inlaid with decorative features made of alloys of specific compositions chosen for the color and texture effects they develop when the final patination (etching) of the tsuba is performed. The authors discuss five such tsuba they have examined in detail. Because these tsuba had been severely damaged, they were available for technical study, including the removal of cross sections that could be analyzed metallographically. Since the authors took sections through portions of tsuba that carried metal inlays, we have our first clear picture of the ways in which grooves were made to receive inlays and how such inlays were secured. Rarely was solder or any other type of metallurgical join used. Grooves were carved into the base with very sharp chisels. Both the accuracy of fit between groove and inlay and lateral compression of the base metal at the sides of the grooves were responsible for securing the inlays, rather than any mechanical interlock. The photomicrographs illustrating these techniques are excellent.

In the case of forged iron tsuba, the decorative effects are not solely dependent upon the contrast between base metal and inlays. Some iron tsuba have no inlays whatever. The surface texture of the iron, known as mokume-hada, is achieved by revealing the distorted grain of the metal (the lamellae and lines of the forged structure) through deep etching. Chemical etching brings out local variations in color, roughness or level resulting from chemical inhomogeneity both in intentional constituents of the metal, such as carbon, and in impurities like nickel, copper, and arsenic.

As expected, most of the inlay on these tsuba was of a metal different from that of the ground. A totally unexpected finding was the use in some areas, on both the iron and non-ferrous tsuba, of relief inlay of the same metal as the base. This was apparently done to simplify the shaping of the inlay, but the fit was so perfect and the finishing so fine that there is no external hint of the presence of a joint. Several other inlay techniques were found which do utilize molten metal: sawari: a high tin-copper alloy, approximating speculum metal, which is melted into the grooves and then polished and ground flat; gomoku-zōgan: an irregular array of pieces of brass secured to the surface of an iron tsuba with a high zinc brazing solder; suemon-zōgan: large, well shaped areas of brass with relief design attached with soft solder to the surface of an iron tsuba.

One of the most beautiful and characteristically Japanese texture and color decorative techniques is exemplified on tsuba by guri-bori and non-ferrous mokume. Guri-bori consists of a stacked composite of alternating sheets of copper and shakudo (copper-gold alloy). The layers are joined with solder. By cutting grooves deeply and at varying angles through the stack, layers of different thickness and color are revealed. Mokume is also a composite of soldered sheets but the laminates are thinner than in guri-bori and are intentionally distorted into an irregular shape through which the smooth final surface is cut. The resulting pattern is often of irregular, never intersecting lines, like contour lines on a map.

Regardless of the kinds of metals used, the final treatment of Japanese metalwork consists of producing a patina by chemical attack. Except in the case of gold and sometimes silver, the colors one sees on tsuba result from thin layers of oxides, sulfides or other compounds produced by chemical reaction that modifies the reflection of light from the surface of the metal. As the authors point out, it takes great skill to give the many different alloys their properly balanced colors by the same, overall, final patination.

“The beauty of any work of art lies less in the materials and techniques that are used than in what is done with them. [Nevertheless] the symbolism and aesthetic overtones could not exist without a technical underside” (p. 327). This is surely the message brought home not only by these tours de force of Japanese craftsmen and by Elaine Savage and Cyril Stanley Smith but by this volume as a whole. It is certainly one of the assumptions that motivated John Gettens' research throughout his stimulating and productive career.

The following is a complete list of the articles in Ars Orientalis, Vol. 11 (1979).


Copyright 1980 American Institute of Historic and Artistic Works