Ceramics is a craft that relies not only on the aesthetic sense and manual dexterity of the maker, but also on the dynamism of chemistry to bring it to completion.
In the world of painting and calligraphy, what you draw becomes the work of art, but in the case of ceramics, the work is not yet completed even though the clay is shaped, painted and glazed. The work must go through a final process of firing. This firing process chemically alters the clay, paint and glaze, giving the craft of ceramics an ineffable depth.
The transformation of the trait of shape and quality through firing must have been a headache for makers long ago, as it lay beyond their calculations.
However, through repeated trial and error, the process of transformation, which was thought to be accidental, gradually accumulated as data, and ceramics evolved into a craft whose creators could, to some extent, envision the finished form.

For example, vessels painted in blue called seika, which developed during the Yuan dynasty in China, were also made with skillful use of chemical transformation.
One seika piece is completed by painting the shaped clay with gosu paint (zaffer – a pigment containing cobalt oxide), applying a transparent glaze and firing at a high temperature of around 1,300°C. The “before and after” of the dark charcoal grey gosu paint, which develops a blue colour through firing, is quite dramatic.
The name of the first artisan who noticed this transformation is not known, but they must have been astonished when they came across the bright blue colour for the first time as they removed works from the kiln.

Seika vessels blossomed in Japan in the 17th century.
They were introduced to the Kyūshū region when the feudal lords who accompanied TOYOTOMI Hideyoshi on his expedition to Korea brought back Korean potters, and became known in Japan as sometsuke.

The image shows a small dish es from the studio called koubo-zen in Arita, Saga Prefecture, known as the birthplace of sometsuke porcelain.
Made using Izumiyama porcelain stone from the local quarry, they have a rustic freshness reminiscent of vessels from the early days of sometsuke.

Sometsuke was the most advanced painted porcelain in the 17th century, but 400 years later it has become common tableware in Japan.
The reason it has remained so beloved over such a long period of time is, I believe, that the purity and gracefulness of the colour blue enhances the colours of the foodstuffs.
When you use sometsuke ware while thinking about the many years over which potters have passed down this particular technique, you can feel a special touch of elegance even on a familiar dining table.