Hotarude: Rice-Grain Porcelain That Glows When Held to Light

Hotarude is a technique in which small holes are cut through a porcelain body, then filled with clear glaze and fired. Where each hole was, the fired piece holds glass. Held up to a light, those points alone come up bright. The name borrows the light of the firefly, hotaru. In English the technique is usually called rice-grain porcelain.

How hotarude differs from openwork

Hotarude is often confused with openwork carving. There is only one difference.

Hotarude grew out of openwork carving. Because the glaze seals the holes, the piece can take water or tea. Openwork left as it is cannot hold liquid.

How hotarude is made

There are four stages to making hotarude.

• 1. Form it and let it dry　The shape is thrown or moulded, then dried. Some work is cut while the clay is still damp, but where there are many holes the maker waits until it is dry and uses a drill-like tool. Damp clay moves, and fine holes cannot be kept even.
• 2. Cut the holes　They run 0.5 to 2mm. Any larger and the glaze will not bridge them at the next stage. The same applies to a thick body: if the cut is wide, the glaze cannot cover it and the hole stays open.
• 3. Fill the holes with clear glaze　This calls for a viscous glaze that will not run. A thin, watery glaze slides off during firing and leaves the holes open.
• 4. Fire it high　Porcelain is fired at 1,200 to 1,300°C. At that heat the glaze turns to glass, and each filled hole becomes a window that light passes through.

Why hotarude is rare

Hotarude loses a great deal of material, and it takes time.

• Every hole weakens the body　The holes go all the way through. The more of them there are, the more likely the piece is to crack while drying or firing.
• A glaze that runs leaves holes open　Even a glaze chosen for viscosity will move with temperature and thickness. One hole left unfilled and the piece cannot be used.
• You find out at the very end　There is no way to know whether the holes closed until the kiln is opened.

The labour and the loss rate do not add up, and few makers work this way today. Coming across hotarude in a shop is genuinely uncommon.

Where hotarude came from

Hotarude did not begin in Japan.

In Japan it appears above all on the porcelain of Hizen, and Arita in particular. Arita ware was the first porcelain fired in the country, and the region had the skill to make a thin white body. The conditions hotarude needs were already in place there.

What to look at when choosing and using hotarude

• Hold it to the light　This is the only way to look at it. Not the shop lighting, but a window or a lamp. That is where you see whether the holes line up and whether any were left unfilled.
• Run a finger over it　The filled points sometimes dip very slightly. If nothing catches or feels rough, they closed cleanly.
• Think about where it will sit　The quality only shows where there is light. On a table, near a window; on a shelf, with a lamp behind it.
• Wash it as you would porcelain　The holes are sealed, so no water gets in. It needs none of the sealing described in caring for stoneware.

Related reading

The body and the glaze

• Japanese Porcelain: Made from Stone, Not Clay
• Stoneware vs Porcelain: How to Tell Them Apart
• Japanese Pottery Glazes: The Main Types Explained

Other decorating techniques

• Five Decorating Techniques on Japanese Pottery
• Sometsuke: Blue and White Porcelain, Explained
• Shita-etsuke: Underglaze Painting and Why It Never Fades

Where hotarude is found

• Arita Ware: Japan's First Porcelain, 400 Years On
• Kutani Ware: Japan's Boldest Ceramic Painting
• Kyo Ware and Kiyomizu Ware: Kyoto's Refined Ceramics

Pieces available at Nokaze

• Arita Porcelain | Hand-Painted Japanese White Porcelain