MINERALS

Carbonate ion: Main Effects & Top 5

Published May 5, 2026·1min read

Carbonate ion (CO₃²⁻) is the key component of alkaline hot springs. Its strong alkalinity gently dissolves surface proteins — the true source of the famous "silky" feel.

Table of Contents

What is Carbonate ion?
Main Effects
Carbonate ion Top 5 Hot Springs

What is Carbonate ion?

Carbonate ion (CO₃²⁻) is the key component of alkaline hot springs. Its strong alkalinity gently dissolves surface proteins — the true source of the famous "silky" feel.

Main Effects

The source of the "silky" feelThe strong alkalinity of carbonate ions gently emulsifies and dissolves old keratin proteins on the skin's surface. This action is what creates the distinctively smooth and slippery sensation often described as a "silky" feel during bathing.
Key component of alkaline simple springsCarbonate ions (CO₃²⁻) are the primary active component defining alkaline hot springs. In waters with a pH of 8.5 or higher, the chemical balance shifts, causing the ratio of carbonate ions to become greater than that of bicarbonate ions (HCO₃⁻).
Beauty effect via gentle exfoliationBy gently dissolving and removing old, dead skin cells from the surface, carbonate ions promote a natural exfoliation process. This helps reveal the newer skin underneath, contributing to a smoother skin texture after bathing.

Carbonate ion Top 5 Hot Springs

Top 5 hot springs registered on this site with the highest content.

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References

MINERALMay 5, 2026· 1min read

Bicarbonate ion: Main Effects & Top 5

Bicarbonate ion (HCO₃⁻) — the same ingredient as baking soda — gently removes old skin cells and sebum for silky-smooth skin. Known as the "beauty spring" (美人の湯).

SPRING TYPEMay 5, 2026· 2min read

Bicarbonate Springs: "Beauty Waters" for Smooth, Glowing Skin

Bicarbonate springs (HCO₃⁻ as the main anion) are known as "the beauty waters" because bicarbonate gently removes dead skin cells and sebum, leaving skin silky smooth. Indicated for bathing (cuts, cold sensitivity, dry skin) and drinking (gastroduodenal ulcers, diabetes, gout).

SPRING TYPEMay 5, 2026· 1min read

Simple Springs (Tanjun Onsen): Gentle Waters for Everyone

Simple springs have dissolved components below 1,000 mg/kg and a source temperature of 25°C or above. Mild and non-irritating, they are safe for all ages. Alkaline simple springs (pH 8.5+) are famous for leaving skin silky smooth.