Under the glaze: why the painting stays put

Updated 14 October 2026

Run a fingertip over the cat on one of our painted cups and you will feel glaze, not paint. The drawing is underneath, sealed in. That is what "underglaze" means, and it is the most common craft claim in our shop: the sellers of nine of our eleven pieces say their decoration sits under the glaze, and seven of those say a person painted it.

The order of the work

On an underglaze piece, the colour goes on before the glaze. The painter works on the shaped clay, then the whole piece is covered in a clear glaze and fired hot enough for that glaze to melt into a layer of glass. The picture ends up inside the glass rather than on top of it.

China's national heritage record for underglaze painting at Liling, in Hunan, sets out one well-documented version of the process:

1. The shaped body is fired once at 800 °C to strengthen it. 2. It is painted with underglaze colours, using a method called 双勾分水填色: a double outline, then washes of graded strength filled inside it. 3. Glaze is sprayed over the painting. 4. The piece is fired again at 1,350 to 1,410 °C.

Not every workshop follows those exact steps or temperatures. The order is what they share: paint, then glaze, then fire.

Jingdezhen's own history puts the start of this kind of painting in the Yuan dynasty, with blue-and-white. Cobalt was painted onto white porcelain under the glaze, "only one blue", in the words of that history, yet laid on in washes deep and light enough to read as many tones.

Under, in or on

There are two other places a painting can sit. Overglaze colour is painted onto a piece that has already been glazed and fired, then fixed in a second, cooler firing, so it rests on the surface. In-glaze colour is fired hot enough to sink partway into the softened glaze. A 2024 study in the journal 中国陶瓷 (China Ceramics) looked at decorated tableware and found exactly that layering: overglaze decoration on the surface, in-glaze partly sunk into the glaze, and underglaze on the body beneath it.

So the painting on an underglaze cup stays where it was put because the glaze covers it, and the spoon, the sponge and your lips touch the glass instead of the paint. None of our sellers claims overglaze or in-glaze decoration.

Painted by hand, so no two match

Underglaze painting can be printed or hand-done. On most of the pieces we carry, the studio says a person did it, and several say what that means for you:

The Bakery Cat cups: the studio says brush marks show and details differ from cup to cup.
The Brush-Painted Cat Cup: the studio says the drawing, brushwork and colour differ a little on every cup.
The Cat Relief Mug and the bakery cups: the studio says each picture is painted by a craftsperson and then fired above 1,000 °C, and that the depth of the painting varies.
The flower-rim cups: the studio says its panels are painted by hand under the glaze in contrasting colours.
The Strawberry Relief Cup: the studio paints its raised strawberries by hand under the glaze and says they will not fade.

Firing temperatures, where a studio gives one, are the studio's own figures. We have not measured them.

The pieces in this story

Brush-Painted Cat Cup
Bakery Cat Coffee Cups
Cat Relief Mug
Bakery Relief Cups and Toast Plate
Flower-Rim Cup and Saucer with Painted Animals
Strawberry Relief Cup
Speckled Cup and Saucer with Raised Painted Motifs

Under the glaze: why the painting stays put

The order of the work

Under, in or on

Painted by hand, so no two match

The pieces in this story

Sources

More from the journal