Flowing Natural Hot Springs
The source flowing from 1200m underground is the first “sodium and calcium chloride spring” in the Kyoto Basin and it has been confirmed that it has high-concentration spring quality (9146ppm) close to seawater (19000pm) which is rare for hot springs located far away from the sea. In addition, it has also been confirmed that those hot springs have chlorine ion concentration (9146ppm) corresponding to 9 times of what is considered as the reference value for medical treatment hot springs (1000ppm), making them medical treatment hot springs having a variety of effects.
In general the term hot spring refers to a spring containing at least 1 component in the 19 kinds of essential substances listed in the Hot Spring Law or containing an existing solvent substance with more concentration than in the specified amount or mineral water/hot water having a temperature superior to 25 degrees. Tenzan no Yu (source) is a natural hot spring which contains 6 essential substances and its temperature is 31.3 degrees Celsius.
Spring Quality Effects (sodium and calcium chloride spring)
The spring quality of this hot spring is called sodium and calcium chloride spring, including sodium ions (3212mg) and calcium ions (912mg) in large quantity. Sodium ions and calcium ions are reacting with the sebum (carboxylic acid) on the surface of the skin and form carboxylic acid, sodium and calcium salt. The sodium carboxylate is a surfactant which has, generally speaking, the same effect than “soap". Its effect penetrates every corner of the skin, removing all impurities and because of its emulsifying effect “moisten” the skin. For in calcium salt there is the same effect than in “baby powder” it will make your skin feel “silky”.