Originally harnessed by Japanese craftsmen over four hundred years ago for its natural purifying properties, activated charcoal has recently undergone something of a renaissance. What was once a little-known secret has transformed into a popular resource with hundreds of users and just as many uses. Its most creative interpretation may just be the Chikuno Cube, an ingeniously designed miniature air refresher that uses the properties of charcoal to banish odors and humidity around the house. In this special Deep Dive series, we explore the Chikuno Cube, from its origins in the charcoal kilns of Kyoto to the science behind its unusual honeycomb structure.

*The Chikuno Cube House in Small and Large.*

How It Works

To understand how the Chikuno Cube works, we first need to understand the basic properties of activated charcoal. Activated charcoal is a highly absorbent type of charcoal that has been used as a natural purifier in Japan since the Edo period (1603 – 1868). When used correctly, activated charcoal naturally pulls moisture from the air, relieves humidity, and purifies drinking water, all without the use of plastic filters.

The Chikuno Cube is infused with activated bamboo charcoal from Kyoto, which is an especially sturdy and long-lasting species. Bamboo charcoal is activated by burning and carbonizing the branches in a specialized kiln over a period of 2 to 3 days. Towards the end of the kilning process, they are blasted with heat and starved of oxygen until they glow white hot. When the branches reach roughly 2300°F, they are taken out, rapidly cooled, and smothered with ash. This process carbonizes the wood, creating thousands of microscopic cavities that chemically bind with ions to attract, trap, and neutralize impurities. The result is a powerfully absorbent natural purifier that neutralizes toxins and contaminants found in the air.

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How It’s Made

The Chikuno Cube is made from natural clay materials infused with activated bamboo charcoal. Through this process, the Chikuno Cube acquires the same absorptive properties and becomes a natural air refresher. The cube is pressed with a micro-honeycomb texture that is engineered to optimize the total surface area of the charcoal, amplifying its reach beyond the cube itself.

*One Chikuno Cube covers 17 sq. feet, working best in enclosed spaces like small closets and bathrooms.*

Smart Design

One of the defining characteristics of Japanese design is its consistent combination of modern aesthetics and highly functional features. From its honeycomb pattern to the use of natural materials, every aspect of the Chikuno Cube’s design is carefully considered to amplify both its beauty and its purpose. The Chikuno Cube is made from clay and activated charcoal, two natural materials that are 100% recyclable after use. Even the process of activation lends a higher purpose, since it greatly increases the surface area of charcoal branches, allowing the charcoal to chemically adhere to toxins and contaminants outside of itself.

*The micro-honeycomb structure of the Chikuno Cube helps amplify the absorptive properties of activated charcoal.*

Beyond the absorptive properties of activated charcoal, the Chikuno Cube features a hexagonal honeycomb texture designed to increase the surface area and reach of the charcoal itself. Commonly used by bees to store pollen and honey, honeycombs contain hexagonal pockets that pack in amplify the available surface area of the comb, allowing bees to pack in more resources within the same space. In a similar way, the honeycomb structure of the Chikuno Cube amplifies its surface area to pack in and trap more particles from the air. As a result, a 30g honeycombed cube packs in as much absorptive power as a 10kg solid cube, without taking up quite as much room. Although each cube is only 1 ½ inches tall and wide, a single cube is able to cover an area of 17 sq. feet outside itself- approximately the size of a small closet or bathroom. Stacking Chikuno Cubes together expands the overall surface area so that a large Chikuno House (which features four cubes) can cover a space of up to 68 sq. feet.

*One 30g Chikuno Cube has the same surface area as 10kg of activated charcoal.*

The thoughtful and functional design earned rave reviews upon release and subsequently won a prestigious Good Design Award, a top honor in the world of Japanese design.

How it Works

Unlike common air fresheners, activated charcoal does not cloak odors. Instead, the Chikuno Cube absorbs scents and neutralizes them, essentially clearing the air from pollutants like formaldehyde and toluene. Because of this, the cube itself won’t acquire a smell even as it pulls odors from the air.

*When properly cared for, a Chikuno Cube will last up to 12 months. To refresh the cube, place it under full sunlight for half an hour once a month.*

Activated charcoal is a passive purifier, meaning that it slowly and consistently absorbs unpleasant scents and moisture over a period of 12 months. Its effects are most powerfully felt when placed near strong odors like smoke, fish, mildew, burnt food, sweat, and trash. Beyond banishing odors, the Chikuno Cube can be used to treat particularly damp spots in the home like musty basements and mildewy bathrooms. To ensure the cube stays absorbent, we recommend placing it under full sunlight for half an hour once a month. The sun’s rays will recharge the charcoal’s absorbency and keep the cube as good as new.

A Variety of Uses

Though most people use the Chikuno Cube around the house as a preventative measure, its powers are most strongly felt when it’s strategically placed near areas of need. Here are some places around the home where we recommend using the Chikuno Cube.

Near the oven to dispel the smell of smoke or burnt food.
Inside the refrigerator in place of a box of baking soda.
In a small bathroom or powder room to prevent dampness and mildew.
Near a litter box to absorb unpleasant odors.
Inside a car to ease the smell of exhaust.
In the shelf of a linen closet to keep laundry smelling fresh.
Tucked in a corner of your car to keep the seats smelling fresh.

Good To The Earth

Unlike plastic air refreshers, the Chikuno Cube is 100% recyclable and can be re-purposed as soil compost. Once your twelve months of use are up, break the cube into bits (you can use a hammer) and bury them in your garden. The charcoal-clay bits will help stimulate natural growth and nitrogen production. The tiny pores in the charcoal help aerate the soil, increasing microbial activity and creating healthy natural soil for your beloved plants.