OSAKA--When the sun sets, signs made with a special tile material produced by an Osaka-based startup company help light up the night across Japan. 

The material, called Luna Ware, soaks up energy during the day and releases it at night, shining brightly.

Luna Ware is now used in emergency exit signs at station complexes in Tokyo’s subway system and on a building in Wakayama Prefecture. It is also used in stations and school signboards in Fukushima Prefecture.

Developed by Codomo Energy Co., Luna Ware is made by admixing glassy glaze with luminous pigment before the firing process.

The company said it can continue to glow at night for more than 12 hours after it has stocked up on sunlight or artificial illumination during the daytime.

The product does not rely on electricity, so it is eco-friendly and can glow even during a blackout. It is resistant to flood and fire disasters because its glow-in-the-dark features are not lost by exposure to water or flames.

It withstands wear, so it can be used in floor surfaces with heavy foot traffic.

The Luna Ware material produces illumination when it is crushed into pebble size and scattered on the ground. That is how it is used at tourist spots across Japan, including at Kyoto’s Daigoji temple, a UNESCO World Heritage site.

GAINED ATTENTION IN 2018 CAVE RESCUE

The Luna Ware also played a role in the 2018 rescue of 13 people, most of them boys, trapped inside a cave in Thailand, which held the world spellbound for more than two weeks.

A big pool of water created by heavy rains separated the boys in the back of the cave from its entrance. Rescuers in the dark had rough going.

Enter Yasunori Iwamoto, president of Codomo Energy, who offered to provide several hundred pieces of a Luna Ware product.

Divers wore some of them on their helmets and flippers to allow themselves to be located by their colleagues and dropped others onto the bottom of the pool so they would serve as guides, officials said.

IDEA CAME FROM PORCELAIN MAKING

Iwamoto, 59, started out as a builder who worked, among other things, on installing modular baths and remodeling houses and other structures.

He sometimes handled building materials that contain toxic chemicals. He thus developed a desire to realize lifestyles that are friendly to humans and the environment alike, for which purpose he founded Codomo Energy in 2004.

He named his company after “kodomo,” the Japanese for child(ren), out of a wish to safeguard young ones, who will be the main players of the next generation.

He began developing the Luna Ware after he learned about a product of Arita ware, traditional porcelain from Saga Prefecture, that used a luminous pigment. He thought about drawing on that technology to make a product for power-saving and disaster management purposes.

Plastic and other products that used luminous pigment were already available, but Iwamoto thought he would be able to make a brighter product.

He drew on Arita ware’s technology for coating porcelain with glaze and firing it to create a vitrified layer.

He thus created the Luna Ware, whose glow-in-the-dark features are semipermanent because it is made by admixing glaze with luminous pigment before the firing process so the pigment ends up vitrified and shielded from air and moisture.

Iwamoto released the first Luna Ware model for sale in 2009 and continued improving it.

He had three kilns installed at the back of the head office and made hundreds of trial products to study, again and again, at what temperatures, and for how many hours, the products should be fired to achieve improved features.

The current Luna Ware model was completed sometime around 2013 or 2014 at the end of a decade or so of development.

An emergency exit sign product using the Luna Ware has been certified by an institution registered with the Fire and Disaster Management Agency as satisfying its performance requirements.

PRODUCED IN FUKUSHIMA AS A SYMBOL

The company’s Luna Ware mass-production plant was set up, following the Fukushima nuclear disaster of 2011, in Kawauchi, Fukushima Prefecture, not far from the crippled Fukushima No. 1 nuclear power plant.

Iwamoto had no connections with the disaster-hit community, but he decided, partly at the urging of concerned officials, to help push rebuilding work by creating jobs there.

Fukushima Prefecture is a symbolic terrain where nuclear power, one of the conventional energy sources, revealed its own limitations. Iwamoto thought that making a power-free, luminous tile product there could help stimulate thoughts on energy sources of the future.

The Luna Ware, unfortunately, is somewhat expensive. An emergency exit sign with a standard size of 14 centimeters or so per side costs about 25,000 yen ($220).

Iwamoto, however, remains as passionate as when he was first developing the Luna Ware.

“Our product will gain recognition in the end if only it is useful,” the president said.