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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.
RANKING BY THIS MINERAL CONTENT
Top 5 by Content
* Top 5 by mineral content matching the filters among onsen analysis records registered in this app
ANALYSIS REPORTS WITH THIS MINERAL
See onsen that contain this mineral
Onsen analysis reports visualized by minerals, pH, temperature, and a 5-axis profile. The carousel updates as you change the filters above.
Shotokuji Onsen Hatsuhana
Spring water that is gentle on the skin with a very low likelihood of irritation. Safe for bathing infants and those with sensitive skin.
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Nestled in the quiet countryside of Yamanashi City, Shotokuji Onsen Hatsuhana is a beloved local retreat with a long history of soothing tired bodies. The highly alkaline waters wrap the skin in a silky, moisturizing embrace. This spring is especially recommended for those seeking a peaceful escape from daily stress or looking to care for dry, sensitive skin.
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
A natural moisturizer also used in skincare lotions. Forms a thin veil on the skin to reduce moisture loss after bathing.
Nestled in the quiet countryside of Yamanashi City, Shotokuji Onsen Hatsuhana is a beloved local retreat with a long history of soothing tired bodies. The highly alkaline waters wrap the skin in a silky, moisturizing embrace. This spring is especially recommended for those seeking a peaceful escape from daily stress or looking to care for dry, sensitive skin.
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
A natural moisturizer also used in skincare lotions. Forms a thin veil on the skin to reduce moisture loss after bathing.
Isawa Onsen
Spring water that is gentle on the skin with a very low likelihood of irritation. Safe for bathing infants and those with sensitive skin.
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Nestled in the fruit-growing countryside of Kasugai-cho, Fuefuki, Hinode Onsen has long been cherished as a local retreat by Ryokan Hinode. Its gentle, mildly alkaline waters are ideal for anyone seeking a soothing soak after a busy day, or for those with sensitive skin looking for a stress-free bathing experience.
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
Nestled in the fruit-growing countryside of Kasugai-cho, Fuefuki, Hinode Onsen has long been cherished as a local retreat by Ryokan Hinode. Its gentle, mildly alkaline waters are ideal for anyone seeking a soothing soak after a busy day, or for those with sensitive skin looking for a stress-free bathing experience.
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
Onneyu Onsen Tsutsuji Sou
Spring water that is gentle on the skin with a very low likelihood of irritation. Safe for bathing infants and those with sensitive skin.
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Onneyu Onsen, whose name means "large hot spring" in the Ainu language, is a famed Hokkaido spa renowned for its abundant waters. The Izumi-go-i source is one of the springs that upholds the area's legacy as a "skin-beautifying" destination, cherished since its opening in 1899. Its clear, highly alkaline water gently exfoliates the skin, leaving it with a silky-smooth feel. This source provides 100% pure, natural hot spring water—never heated, diluted, or recirculated—to soothe the body and soul of its visitors.
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
Onneyu Onsen, whose name means "large hot spring" in the Ainu language, is a famed Hokkaido spa renowned for its abundant waters. The Izumi-go-i source is one of the springs that upholds the area's legacy as a "skin-beautifying" destination, cherished since its opening in 1899. Its clear, highly alkaline water gently exfoliates the skin, leaving it with a silky-smooth feel. This source provides 100% pure, natural hot spring water—never heated, diluted, or recirculated—to soothe the body and soul of its visitors.
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
Suzuka Circuit Natural Onsen The Spa
Spring water that is gentle on the skin with a very low likelihood of irritation. Safe for bathing infants and those with sensitive skin.
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Suzuka Circuit Onsen is a unique hot spring located on the grounds of the world-renowned Suzuka Circuit racetrack. For years, it soothed race fans and families at the "Kur Garden" facility, which opened in 1994. This pump-lifted spring became the perfect spot to cool down and refresh after the excitement of a race. Since 2023, it continues its legacy of healing at the new guest-exclusive "THE SPA".
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
A trace component with gentle antibacterial and anti-inflammatory action.
Suzuka Circuit Onsen is a unique hot spring located on the grounds of the world-renowned Suzuka Circuit racetrack. For years, it soothed race fans and families at the "Kur Garden" facility, which opened in 1994. This pump-lifted spring became the perfect spot to cool down and refresh after the excitement of a race. Since 2023, it continues its legacy of healing at the new guest-exclusive "THE SPA".
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
A trace component with gentle antibacterial and anti-inflammatory action.
Yoshiikeryokan
Salt content forms a protective barrier on the skin and prevents moisture and heat from escaping the body even after bathing. Boosts heat retention and has moisturizing effects.
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※ Only at facilities permitted to serve drinking water. 200–500 mL/day recommended.
The Yumoto Onsen Mixed Spring (Registers 12, 72, 84, 89, 99, and 112) is a luxurious blend of six distinct sources gushing in the Hakone Yumoto area. Symbolizing the abundant waters of historically renowned Hakone, this spring generously supplies leading local inns, continuously soothing bathers with its stable and comforting mineral qualities.
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
A trace component with gentle antibacterial and anti-inflammatory action.
The Yumoto Onsen Mixed Spring (Registers 12, 72, 84, 89, 99, and 112) is a luxurious blend of six distinct sources gushing in the Hakone Yumoto area. Symbolizing the abundant waters of historically renowned Hakone, this spring generously supplies leading local inns, continuously soothing bathers with its stable and comforting mineral qualities.
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
A trace component with gentle antibacterial and anti-inflammatory action.
References
Related Articles
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).
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).
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.