The Beauty of Gosu Blue Satsuma

What is Gosu?

Gosu (呉須) is the Japanese term for traditional cobalt-based blue pigments and enamels.  Japanese use of the term gosu may indicate either the pigment itself, overglaze glassy enamels made using this pigment, underglaze use of the same pigment (ie, as in sometsuke blue-on-white porcelain) or even sometsuke ware itself.  However, in regard to Satsuma ware, the term gosu always means overglaze glassy enamels made using this pigment. Other uses of the term gosu are discussed in the site’s Illustrated Glossary.

However, gosu pigment can be combined with a variety of other earth materials to produce blue overglaze enamels. It is these blue overglaze enamels which characterise gosu blue Satsuma wares.  Gosu blue Satsuma was sometimes called “Imperial Satsuma” by Europeans in the late 19th century. Takamatsu (1878) gives a formula for a glassy blue enamel used on Kutani ware as also including shiratama (powdered clear lead glass) and tonotsuchi (white lead oxide) in addition to what was probably hanakonjo, said to be a mixture of crude cobalt oxides, clays and alkalies.[2]

Gosu blue enamel is analogous to the European pigment “smalt”, which is deep blue coloured potassium glass prepared by including a cobalt compound, typically cobalt oxide or cobalt carbonate, in a glass melt. Cobalt is a very intense colouring agent and very little is required to produce a noticeable colour in the glass. When ground, smalt was used as an artist’s blue pigment, primarily from the 15th to the 18th centuries.  Takamatsu equates hanakonjo enamel with smalt (pp 23, 29), as does Andacht.[3]

Unfortunately, there is no unanimity amongst either scholars or collectors on these questions. As far as is known, there is no scholarly work on dating gosu blue Satsuma. 

Sandra Andacht’s Treasury of Satsuma (1981) labels the many fine examples of gosu blue Satsuma shown in that book as all dating between 1795 and 1872 (ie late Edo and the very beginning of Meiji). Andacht dates the beginning of this period to early in the Kansei era (1789-1801), following the introduction to Satsuma province of existing Kyoto techniques for decorating earthenware with overglaze enamels (pp 37-38).  According to Andacht, the end of this gosu blue period was based on the introduction of European industrially refined cobalt oxide to Arita in 1869 by German chemist Gottfried Wagener (p 39). Being a cheaper product than gosu, this alternative “cobalt blue” pigment rapidly spread throughout Japan, particularly in the case of the underglaze blue used for decorating porcelain, such as Arita and Imari wares.

Hazel Gorham’s Japanese and Oriental Ceramics (1971), puts a similar view, suggesting that nishikide (brocade) and kin nishikide (gold brocade) Satsuma was being produced from late in the 18^th century (pp 80-81).

However, many collectors and some later writers hold the view that the majority of gosu blue Satsuma production falls in a much smaller and later window (say 1850-70). Some collectors have extended this small production window to approximately 1850 -1900.  While not denying that earlier nishikide and kin nishikide Satsuma wares were produced, it is considered that the great majority of pieces (including the very great majority of pieces available to Western collectors) were produced AFTER the time when Japan began to export large quantities of ceramics to the prime Western markets, ie from 1870. Gisela Jahn’s Meiji Ceramics (2004) states that the two largest kilns in Satsuma province (those of Chin Jukan and Boku Seikan) both expanded “enormously” after the rapid growth of the export trade at the beginning of Meiji (p 107).

Indeed, there seems to be good reason to hold the view that many gosu blue pieces were produced during the period 1870-1900 (or even slightly later). As the Gotheborg website says: “Some prefer a later date (say mid to late Meiji, the hey-day of Japanese export ceramics, at least by quantity).” There seems no reason to believe that export of gosu blue Satsuma would do anything else but mirror the rises and falls in export of other types of Satsuma ware, providing that gosu was still in use and remained readily available.

Some degree of corroborating evidence is provided by the many examples of gosu blue Satsuma with raised gold slip outlining (moriage technique), which became very popular on Kyo Satsuma during the period 1880-1900. In addition, many gosu blue Satsuma pieces are signed by the artist (sometimes also with an impressed mark from the potter). The fashion for such marks really only got going on Kyo Satsuma in the 1880s.

The most recent substantial English book on Satsuma, Louis Lawrence’s Satsuma, The Romance of Japan (2011), goes even further. In writing on Satsuma “with heavy enamelling”, Lawrence says “I have heard them referred to as ‘imperial’, ‘Gosu’, ‘early’ and ‘Edo’ Satsuma. … They are not early pieces made in the Edo period or even the early Meiji period; they date between the 1880s and the late 1920s” (p 134). He also gives a dated example from the Yokohama workshop of Hododa with an original label indicating that it was made for exhibition circa 1900.

In conclusion, it is considered that most pieces of gosu blue Satsuma were made between 1870 and 1900. A minority may predate this period and some may postdate it, particularly if made in Kagoshima.

Other Characteristics of Gosu Blue Satsuma

It is difficult to say why gosu blue Satsuma is so attractive to collectors. It certainly has to do with the hard-to-define glassy grey/blue hue, which is immediately distinguishable from the dark, even-toned blue of industrial cobalt pigment.

In addition, the overall quality of gosu blue Satsuma is undoubtedly higher than the majority of Satsuma wares from Kyoto and other mainland centres. While Kyoto (in particular) and the other mainland production centres (eg Osaka, Kobe, Tokyo and Yokohama) certainly produced some outstanding pieces, they also produced vast quantities of export ceramics of poor and very poor quality. This does not seem to be the case with the Kagoshima potters and decorators. Also, there are definitely fewer gosu blue pieces available.

Another key aspect of the beauty of gosu blue Satsuma is the style of decoration. Gosu blue was generally used with traditional designs, such as brocades (nishikide), bird and flowers (kacho-ga) and various floral motifs. Geisha, family scenes, landscapes, Samurai, mythological heroes, rakan and the like, rarely appear (if at all) on gosu blue Satsuma. Many collectors prefer the more traditional motifs, as they are more related to Japanese design. Commonly, there is more “white space” on gosu blue Satsuma, which allows the design to stand out in contrast to the very pleasing crackled ivory ground.

There are a number of major shifts in decoration style in Satsuma in the late 19th century, the early 20^th century and the years before the second World War. However, most (if not all) of these took place in Kyoto, Yokohama and other mainland centres of Satsuma production, rather than in Kagoshima. These various styles of decoration, as an assistance to dating Satsuma wares, are addressed in How Old Is It? Clues on Dating Satsuma Wares.

A Final Word

Any conclusions regarding the dating of gosu blue Satsuma, particularly after the rise in popularity of imported industrial cobalt oxide pigment, must consider the source of the blue colouration.

Did some producers of Satsuma ware, particularly in Kagoshima, maintain access to a native Japanese source of gosu cobalt? Or, did they continue to import the more expensive and difficult to use Chinese gosu pigment?

Perhaps a third alternative is that blue enamels were produced using blue copper carbonate (ie azurite, known as konjo), instead of cobalt smalt (ie hanakonjo).

This site considers that it stands to reason that blue glazes used in the period after 1870 could only have been produced from two key blue minerals – ie konjo and hanakonjo. If it was the cobalt-based hanakonjo, then this could have only come from three sources – those of native Japanese origin, continued imports from China or (conceivably) a clever use of the imported industrial cobalt oxide (with other components) to produce the desired colour and clarity.