Sometsuke: How Japan's Cobalt-Blue Porcelain Found Its Voice
Sometsuke (染付) is the Japanese name for cobalt-blue underglaze decoration on white porcelain — the technique that gave Japan its first true porcelain language and still defines the look most people picture when they think of Japanese blue-and-white. The word literally reads "dye-attaching": cobalt pigment is brushed onto a bisque-fired body, then sealed under a clear glaze and fired again at high temperature. Only after that final firing does the blue appear. This guide covers what sometsuke is, where it came from, four sub-styles worth recognizing, and how to judge quality in hand.
What "Sometsuke" Actually Means
The characters 染付 (some-tsuke) come from someru, to dye, and tsukeru, to attach. In ceramic vocabulary the term refers specifically to underglaze cobalt-blue decoration on porcelain. A hand-painted blue motif applied over the glaze, after the main firing, is not sometsuke; it is overglaze enamel work (上絵付け, uwa-etsuke).
The pigment itself is called gosu (呉須). Raw and unfired, gosu looks grey or black — the brilliant blue is a chemical event, not a color choice. During the high-temperature firing (around 1,300°C), cobalt oxide reacts inside the clear feldspathic glaze and shifts into the deep blue we recognize. The painter is, in effect, drawing in the dark and trusting the kiln to translate.
Atomic fact: Sometsuke = cobalt pigment (gosu) painted on bisque-fired porcelain, covered in clear glaze, and fired once at high temperature (~1,300°C). The blue color appears only after firing.
Where Sometsuke Came From
Chinese cobalt-blue porcelain — qinghua (青花) — was already a centuries-old tradition by the time it reached Japan, and the link ran through Korea. According to long-standing tradition, the Korean potter Yi Sam-pyeong (李参平, also known as Kanagae Sanbee, d. 1655) discovered porcelain stone at Izumiyama in Arita, former Hizen Province, in the early 1600s. That find gave Japan the raw material it had been missing: a white, plastic, high-firing kaolin clay.
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
The geography is tighter than people expect. Arita, Imari, and Hasami all sit within roughly thirty kilometers of one another, straddling the Saga–Nagasaki prefectural border. Arita (Saga) is where the kilns were and where the porcelain was made. Imari (Saga) is the port from which the boats left — which is why European collectors called the ware "Imari" even though almost none of it was made there. Hasami (Nagasaki) developed in parallel as the everyday-tableware partner to Arita's higher-end production. That division of labor has held for four hundred years.
For a wider map see Japan's Pottery Regions; for why this technique only works on porcelain, see Stoneware vs Porcelain.
Four Sub-Styles to Recognize
1. Old Imari / Ko-Imari Sometsuke
Ko-Imari (古伊万里, "Old Imari") covers the export-era pieces shipped through Imari port from the mid-17th century onward. The pure sometsuke pieces — without overglaze red and gold — tend to be more restrained: dense underglaze-blue painting of phoenixes, peonies, karako children, or compartmentalized landscape panels copied from Chinese Kraak porcelain and then domesticated. Brushwork is confident but not always perfectly even, and the porcelain body often shows the gritty unglazed footring that Edo-period Arita is known for. An antique Ko-Imari lidded bowl is a good place to see this idiom up close — our Arita Ko-Imari Lidded Bowl is a working example.
2. Nabeshima Sometsuke
Nabeshima ware (鍋島焼) was the official ware of the Nabeshima Lords of the Saga Domain, produced from the late 17th century into the 19th, with its finest period in the first half of the 18th century. It was never exported during that era. Nabeshima sometsuke is the opposite of Ko-Imari's busy export look: formal, precisely drawn, with carefully spaced motifs that read more like court painting than tableware decoration. The footring is comb-toothed and the body is glassily white. If you see a piece of Japanese sometsuke that feels almost too composed, Nabeshima is the lineage it is quoting.
3. Modern Hasami Sometsuke (Everyday)
Modern Hasami sometsuke is the workhorse tradition — rice bowls, soba choko, side plates, furin wind chimes. The motifs are looser and the brushwork is faster, often with a confident shorthand that comes from generations of repetition. This is where most home cooks meet Japanese blue-and-white. A clean example: the Arita-Hasami Faceted Sometsuke Karakusa Bowl or the Arita Hakuji Stripe Sometsuke Furin.
4. Karakusa (Arabesque)
Karakusa (唐草, "Tang grass") is technically a motif rather than a style, but it is so common in Japanese sometsuke that it functions as a category. The pattern — a continuous flowing vine — came from the Silk Road via Tang-dynasty China and was already abstracted into Japanese decorative vocabulary long before porcelain arrived. On sometsuke it appears everywhere: as a rim band, as an all-over field, as the friendly green-grocer's furoshiki print. A scrolling karakusa drawn with a single confident brush is one of the truest tests of a sometsuke painter's hand.
Atomic fact: The classical sub-styles of Japanese sometsuke — Shoki-Imari, Ko-Imari sometsuke, Nabeshima, modern Hasami daily-ware, and karakusa-pattern work — all share the same cobalt-on-bisque-under-clear-glaze technique. The differences are compositional, not chemical.
The Pine-Bamboo-Plum Vocabulary
Beyond karakusa, a few motif families turn up constantly. Shōchikubai (松竹梅) — pine, bamboo, plum — is the most beloved auspicious trio in Japanese decorative art, signifying endurance (pine), flexibility (bamboo), and renewal (plum-blossom in late winter). On a sometsuke platter the three plants are usually arranged as a single unified composition rather than three separate panels. Our Arita Sometsuke Shōchikubai Oval Platter is a representative everyday example. Other common motifs include goldfish (kingyo, a summer reference), chrysanthemum (kiku), seigaiha wave patterns, and the various crane-and-pine longevity sets.
Sometsuke on Glass — A Quick Note
Cobalt blue is not exclusive to porcelain. Edo Kiriko — the cut-glass tradition of Tokyo, formally designated a Traditional Craft by Japan's METI — uses cobalt-blue cased glass. Cobalt oxide is melted into the outer layer at around 1,350°C, a clear inner layer is fused inside, and the cutter carves through the colored skin to reveal the clear glass below. Different craft, related chemistry — the blue sits in the same family as the gosu of an Arita plate.
How to Identify Quality Sometsuke — A Buyer's Checklist
Holding a piece of sometsuke in your hands — at a fair, in a shop, on a kitchen counter — these are the four things worth checking.
Line Strength
Look at the outline brushwork. A confident sometsuke line varies subtly in width as the painter pivots the brush, never gets shaky, and never doubles back to correct. Mechanical, perfectly even lines usually indicate transfer-printing rather than hand-painting; that is not automatically a flaw, but it is a different category of object and should be priced differently.
Blue Evenness and Depth
Gosu fired well sits inside the glaze with depth — the blue should look like it is suspended a millimeter below the surface, not painted onto it. Patchy, flat, or grey-leaning blue often points to under-firing or to a thinner, lower-grade pigment. Hold the piece against natural daylight and tilt it; the best blues will shift slightly in tone as the angle changes.
Bisque Whiteness
The white ground is doing more work than people realize. A clean, slightly cool white amplifies the cobalt; a yellowish or grey body dulls it. On older Arita pieces a faint blue-grey body tint is normal and not a defect — it is the natural cast of Izumiyama porcelain stone. Check the unglazed footring: that is where the true body color is visible.
Dami Gradation
Dami (濃み) — sometimes dami-wake — is the technique of filling in painted outlines with a wash of diluted gosu to create graded shading. A specialist damishi traditionally handled this step, separate from the outline painter. Well-executed dami gives the blue a soft, watercolor-like body inside crisp outlines; poor dami pools at the edges and leaves dark tide-lines. Looking for clean, even dami is one of the fastest ways to read painter skill on a finished piece.
Atomic fact: Quality sometsuke is judged on four observable traits — line confidence, blue depth and evenness, bisque whiteness, and clean dami gradation inside outlined areas.
A Tradition That Kept Walking
Four hundred years on from Shoki-Imari, the technique has not been replaced. A Hasami rice bowl pulled from a contemporary kiln this season and an early-Edo Arita dish in a museum case are doing the same thing, with the same materials, in the same firing range. The difference is conversation: each generation has added a motif, refined a brush, or rethought the white space.
To see the breadth in one place, browse our Antique Imari & Arita collection, or look at the Fukagawa Seiji 1937 Sometsuke Tea Set for the high formal end of the lineage.
Frequently Asked Questions
Is sometsuke the same as "blue and white porcelain"?
Functionally yes. "Blue and white" covers the technique across China, Korea, Japan, and the European centers that later imitated it; "sometsuke" is the Japanese term, usually reserved for Japanese examples.
Why does the blue look different on antique vs. modern pieces?
Old gosu pigments were natural cobalt ores with iron and manganese impurities, giving older pieces a more variable, sometimes silvery or blackish blue. Modern gosu is refined and produces a cleaner, more uniform tone.
Can sometsuke be made on stoneware?
Cobalt underglaze decoration on stoneware exists in some folk-craft pottery, but is not called sometsuke in strict usage — the term is reserved for cobalt-on-white-porcelain. See our Stoneware vs Porcelain guide.
Is sometsuke dishwasher and microwave safe?
Modern fully-glazed sometsuke porcelain is generally microwave- and dishwasher-safe — no metal pigments sit under the glaze. Antique pieces and any piece with overglaze gold or red should be hand-washed.
What does "underglaze" really mean?
The decoration is applied to the bisque body, sealed under clear glaze, and fixed in the high-temperature firing. The glaze fuses over the pigment and locks it in — which is why sometsuke cannot wear off the way overglaze enamel can.
Editor's Note
This is volume 01 of Color of Utsuwa, our companion series to the main ZenKiln Journal exploring how single colors and surface finishes shape the visual language of Japanese ceramics. Next in the series: the soft white of hakuji, and the matte translucence of celadon (seiji). For our parallel series on lacquerware, see Urushi Studies vol.01 — Wajima-nuri.