Sometsuke: How Japan's Cobalt-Blue Porcelain Found Its Voice
6 min readSometsuke (染付) is Japanese underglaze-blue decoration, strongly associated with blue-and-white porcelain. Cobalt-bearing pigment is applied beneath a glaze, and firing develops the finished colour. This guide follows its Japanese history and offers ways to appreciate brushwork, colour and composition without treating appearance as an authentication test.
What "Sometsuke" Actually Means
The name combines characters associated with dyeing and applying. Sometsuke refers to underglaze-blue decoration; it is especially familiar on porcelain but the term is also used in accounts of pottery. Blue painted over a fired glaze belongs to a different decorative process.
The pigment is called gosu (呉須). Its fired appearance depends on the pigment recipe, body, glaze, application and firing conditions. Raw pigment often looks quite different from its finished blue.
In sometsuke, cobalt-bearing decoration lies beneath the glaze. A particular firing temperature or shade of blue is not universal.
Where Sometsuke Came From
Japanese porcelain developed in the early seventeenth century with an important contribution from Korean potters. The Yi Sam-pyeong (李参平, Kanagae Sanbee) discovery story belongs to a longstanding founding tradition. Arita’s history museum distinguishes that tradition from the archaeological chronology, generally describing the beginnings in the 1610s. Porcelain stone is not simply pure kaolin.
The earliest Japanese porcelains that followed are called Shoki-Imari (初期伊万里, "Early Imari") — small, sparsely painted underglaze-blue pieces for the domestic market in the first half of the 17th century, the founding generation of Japanese sometsuke. Historians today treat the Yi Sam-pyeong narrative as tradition rather than settled fact, but he is still honored as the founding figure at Sueyama Shrine in Arita.
The Arita–Imari–Hasami Corridor
Arita and Imari in Saga and Hasami in Nagasaki are closely connected names in the history of Hizen ceramics. Imari was an important shipping port, while kiln production developed in several areas. Their products, markets and division of work changed over time; Arita was not exclusively luxury production and Hasami was not permanently its everyday counterpart.
For regional context see Japan's Pottery Regions; for ceramic bodies see Stoneware vs Porcelain.
Four ways to explore sometsuke
1. Old Imari / Ko-Imari Sometsuke
Ko-Imari (古伊万里, “Old Imari”) refers broadly to older Imari porcelain and is not limited to export pieces. Blue-and-white examples include varied domestic and export designs. A contemporary bowl in this idiom is not thereby an antique: the Ko-Imari-style lidded bowl should be read through its individual production and condition record.
2. Nabeshima Sometsuke
Nabeshima ware was produced under the patronage of the Saga domain, notably for official gifts. Its best-known designs can show disciplined spacing, precise outlines and carefully treated feet. Those visual features help explain the style; they do not authenticate an object that resembles it.
3. Modern Hasami Sometsuke (Everyday)
Modern Hasami production includes a broad range of everyday tableware and decorative objects, with different painting and manufacturing methods. The Arita-Hasami Faceted Sometsuke Karakusa Bowl and Arita Hakuji Stripe Sometsuke Furin offer contemporary examples; check each listing for its particular attribution and process.
4. Karakusa (Arabesque)
Karakusa (唐草) is a scrolling plant motif, not a body type or historical period. It appears in many materials and traditions. On sometsuke it may form a rim band or cover a whole surface, bringing rhythm through the balance of painted lines and white space.
These examples mix historical periods, production traditions and motifs. They are useful viewing angles rather than a standard classification into four or five exclusive sub-styles.
The Pine-Bamboo-Plum Vocabulary
Shōchikubai (松竹梅)—pine, bamboo and plum—is an auspicious grouping associated with endurance and renewal. Our Arita Sometsuke Shōchikubai Oval Platter offers one example. Other motifs include chrysanthemums, waves and cranes. Blue-and-white can feel visually refreshing at a summer table; see Japanese summer cooling and ryō o toru for the seasonal context.
Cobalt blue in glass — a different craft
Blue glass and ceramic gosu can share cobalt as a colourant, but Edo Kiriko is cut glass, not sometsuke. In coloured cased glass, cuts through an outer colour layer reveal the glass beneath. Recipes and construction differ from underglaze painting on ceramics.
Looking closely at sometsuke
Look for what you enjoy and ask how it was made. None of the following observations alone proves age, origin, hand-painting or market value.
Line Strength
Follow the outline and notice changes in width, rhythm and spacing. Skilled handwork can be very regular, while printing can reproduce irregular marks. If the production method affects your choice, ask for a clear process description rather than deciding from line uniformity alone.
Blue Evenness and Depth
The pigment maker Fukaumi’s firing comparisons show that gosu colour changes with the recipe and firing conditions. Greyish or uneven blue is not automatically cheap pigment or underfiring. Nor must a good blue appear a measured millimetre below the surface.
The white ground
Notice how the body and glaze colour work with the blue. A cool white, grey cast or warmer ground may be part of the intended effect. An exposed foot offers another view, but colour alone does not identify the clay source or date.
Dami Gradation
Dami (濃み) fills outlined areas with gosu using a loaded brush. Look at how the wash relates to the outline and to the composition. Pooling and gradation can be deliberate effects, so one ideal of perfectly even colour should not stand in for the maker’s intention.
Line, colour, ground and painted washes offer ways to appreciate a piece. For attribution and production method, look for documentation as well as visual evidence.
A Tradition That Kept Walking
The relationship between blue pigment, glaze and white space connects early examples with contemporary work. Materials, processes and firing schedules have also changed, while makers continue to reinterpret inherited motifs.
Frequently Asked Questions
Is sometsuke the same as blue and white porcelain?
Blue-and-white porcelain is its best-known setting. Sometsuke is the Japanese term for underglaze-blue decoration and can also appear in descriptions of pottery; it is not a certificate of porcelain material.
Why does the blue look slightly different on older vs. modern sometsuke?
Historical natural cobalt ores and modern pigment recipes can contain different proportions of colouring components. Contemporary makers also formulate varied blues. Pigment, body, glaze and firing all affect colour, so a muted blue does not by itself establish age.
Can sometsuke be made on stoneware?
Yes, the term is also used in discussions of pottery decoration. The Hatakeyama Museum’s account of Kenzan’s pottery, for example, includes sometsuke among his decorative methods. See our Stoneware vs Porcelain guide for the separate question of ceramic body.
Is sometsuke dishwasher and microwave safe?
Check the individual product’s appliance instructions and condition. Cobalt is a metallic element used in ceramic colourants; that is different from a metallic gold or silver decorative layer. Neither blue colour nor an underglaze position certifies appliance safety. See our Japanese porcelain care guide.
What does underglaze really mean?
Underglaze decoration is applied before the covering glaze is fired. The glaze protects the design, but glaze and body can still abrade, chip or deteriorate. “Underglaze” does not mean immune to wear.
Editor's Note
This is volume 01 of Color of Utsuwa, our series on colour and surface in Japanese ceramics. Related studies explore hakuji white porcelain and celadon (seiji). For lacquerware, see Urushi Studies vol.01 — Wajima-nuri.
