It is well known as the hot spring producing Yunohana, which literally means “Hot Water Flower.” These are mineral deposits left by hot springs, used as bathing powder. They can change your bathtub at home into a hot onsen bath with the same smell and effects.
These Yunohana huts began producing it about 300 years ago. This is the only place that uses huts to produce it.
This place also produces alum, Myoban, which is used for the name of the hot spring. Myoban is used as a useful chemical, especially as a food additive.
The good steaming places are selected as the locations for huts indispensable to producing Yunohana. First, the stone floor is made of cobblestones to allow the gas from the underground to gush out evenly in the hut. Then, it is covered with blue clay unique to this area, and a triangle-shaped straw-thatched roof is placed on it.
The gas goes through the gaps between the cobblestones and enters the blue clay, where some components of the gas and the blue clay crystallize. This is Yunohana, growing one millimeter per day. Forty to sixty days later, it is collected, refined, and dried to make the final products.
The temperature inside the hut is stable, even on rainy days. Rainwater never penetrates the roof. The roof straw absorbs and evaporates the water. This prevents the rainwater from melting Yunohana.
The thatched roof can last only three years, no matter how skillfully it is built.
The history continues with experiences and wisdom, and it can be called a “modern chemical plant” of the Edo period.
