Kinsai: Gold Fired Over the Glaze in Japanese Ceramics

Kinsai is decoration in which gold-bearing pigment is painted onto the glaze of an already fired piece, then fired a second time at a lower temperature. The gold band running round a rim, the fine gold tracing the outline of a pattern — almost all of it is made this way.

Kinsai is one form of overglaze enamel painting. Overglaze enamel painting is the name of a process — painting on top of the glaze and firing it on — and the work within that process which uses gold is called kinsai. The lavish style that covers a piece in kinsai is kinrande.

One more term sounds similar: kintsugi. That is a repair in which a broken piece is joined with lacquer and gold powder is dusted over the seam, and it never goes into a kiln. Both are gold on ceramics, but whether it was fired on or held in place with lacquer changes even how you handle the piece.

Kinsai, kinrande and kintsugi

When you see gold on a piece, this is how to tell what it is.

The gold powder used to finish kintsugi is made to be held to the piece by lacquer, and cannot be fired in a kiln. Kinsai pigment is made so that the heat of the kiln fuses it to the glazed surface. The gold may look the same, but passing through a kiln makes it a different material — remember that and the terms stop blurring.

Pieces that look gold but are not kinsai

Some pieces carry a dull metallic sheen over a black or brown ground. Most of these are not kinsai but a glaze high in metal content, fired to produce a metallic texture. No gold is used at all.

The way to tell is how the shine is distributed. Kinsai is painted or laid on as a pattern, so the shining areas have lines and outlines. A metallic colour produced by glaze spreads unevenly across the whole piece, its edges bleeding into the ground.

Three ways of firing gold onto a piece

The gold used in kinsai takes roughly three forms.

• Liquid gold　Gold dissolved into a liquid pigment. It comes out of the kiln mirror-bright without burnishing, and is the usual choice for a gold line at the rim
• Burnish gold　Liquid gold with gold powder added. It emerges from the kiln matte, and burnishing with fine sand or an agate tool brings up a quieter gold
• Gold leaf　Gold beaten into thin leaf, cut to the shape of the pattern and laid on the piece. Enamel work uses a thicker leaf so that it does not burn away

The firing temperature is set by the temperature of the original firing. The guideline given by makers of liquid gold is around 800°C for porcelain fired above 1,300°C, and 700–750°C for pottery fired in the 1,200s. The gold alone is fixed far below the heat the piece already survived.

Because gold fires at a lower temperature than other overglaze enamels, it is often applied last: the reds and greens go through the kiln first, then the piece returns for the gold alone. Every extra trip into the kiln adds labour and the risk of loss.

Yuri-kinsai: sealing gold beneath the glaze

Kinsai normally sits on top of the glaze, but there is a technique that reverses the order. It is called yuri-kinsai, gold decoration under the glaze.

Yoshita Minori of Komatsu in Ishikawa Prefecture was born into a kiln known for the red-enamel kinrande of Kutani ware. After deepening his family's overglaze and kinrande work, he turned to yuri-kinsai. A coloured glaze is fired to make the ground, gold leaf cut to the shape of the pattern is laid on and fired, and a clear glaze is then applied over the whole surface and fired again. On 12 July 2001 he was designated a Holder of an Important Intangible Cultural Property — a Living National Treasure — for yuri-kinsai.

Because the leaf lies beneath a film of clear glaze, the gold never reaches the surface. Gold seen through a layer of glaze is softer, a light that has settled rather than one that flashes.

What to look for in kinsai

• The quality of the shine　The mirror brightness of liquid gold, or the quiet glow of burnish gold. The same metal, entirely different impressions
• The waver of the line　A hand-painted gold line thickens and thins slightly as the brush enters and leaves. A perfectly even width usually means a transfer
• Contrast with the ground　Brilliant over white porcelain, and tightened, more restrained over a black or indigo ground

In Japan, gold has long been the final stroke in the enamelled work of Arita ware, Kutani ware and Kyo and Kiyomizu ware. Somenishiki, which layers colour and gold over indigo underglaze, is one example.

Living with kinsai

Gold resists air, water and sulphur, so it does not darken with time. What sits on the glaze, however, is an extremely thin film of it. It will not discolour, but it does wear away when rubbed.

• Never use a microwave　Gold is metal: it sparks, damaging both the gold and the piece
• Avoid the dishwasher　Hot jets and strong detergent thin the gold
• No abrasives or metal scourers　Wash by hand with a soft sponge and a neutral detergent
• Do not drag metal cutlery across it　Gold wears fastest exactly where a fork or knife lands

Pieces like yuri-kinsai, where the gold lies under the glaze, need far less worry about abrasion. It is still metal, though, so the microwave remains out. Everyday handling is covered in caring for Japanese ceramics.

Related reading

Painting on the glaze

• Uwa-etsuke: How Overglaze Enamel Painting Works
• Kinrande: Gold Fired Over Red Overglaze Enamel
• Akae: The Red Overglaze Enamel of Kutani and Arita
• What Is Somenishiki | Enamel Color Over Blue Underglaze, from Arita

Regions and repair

• Kutani Ware: Japan's Boldest Ceramic Painting
• Arita Ware: Japan's First Porcelain, 400 Years On
• Kintsugi: How to Repair Pottery With Gold (and Why)
• How to Care for Japanese Ceramics: A Practical Guide

Pieces available at Nokaze

• Japanese Blue and White Pottery | Hand-Painted Sometsuke