Kuroyu
Analysis UnverifiedKuroyu is one of four springs of differing character that rise within about 50 meters of one another at Yunotai, said to be the oldest bathing ground of Nyuto Onsen. Long called the "warm-pool spring" and the "spring of fertility," it has the highest chloride content of the four, so a soak warms you to the core and the heat lingers long afterward. The cloudy, sulfur-scented water comes up hot and is tempered with fresh water in some seasons, a robust spring that shows its true worth during deep-snow winter stays.
The bar length shows how abundant each component is compared to thresholds that make it "distinctive" (therapeutic spring standards, beauty spring criteria, etc.).
The source of the distinctive sulfur smell. Dilates blood vessels via skin and inhalation to strongly boost circulation.
Undissociated boric acid with antibacterial action that keeps the skin surface clean.
A "beauty spring" that gently emulsifies dead skin cells, leaving skin smooth after bathing.
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.
▸Note
The temperature, pH and component values shown here are based on the hot spring analysis (source). Actual values in the bath may differ depending on heating, dilution, recycling and filtration. Please check current usage status at the facility.
Of the four springs this one tends to feel the hottest, so pour water over yourself first and take several shorter dips. Remove silver jewelry because of the sulfur, and avoid rinsing off too thoroughly afterward so the warming minerals stay on your skin.
With 876 mg/kg of chloride forming a light film that slows evaporation, the water offers restorative warmth that lasts, while 10.8 mg/kg of free hydrogen sulfide makes it a sulfur spring traditionally linked to immune system stimulation, ideal for winter stays.
The strong warming effect can lead to lightheadedness on long soaks, so drink water often, and avoid lengthy baths in poorly ventilated spaces because of the hydrogen sulfide.
※ See the analysis data below for detailed contraindications
ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- Kuroyu
- Spring type
- Sulfur-containing Sodium Chloride and Bicarbonate Hot Spring (hydrogen sulfide type)
- Source temperature
- 58.7℃
- pH
- 6.8
Analysis Document
- Analysis date
- 2014-08-25
- Analyst organization
- 株式会社 秋田県分析化学センター
- Registration No.
- 秋田第2号
Cations
- Lithium ion Li⁺
- 0.20 mg/kg
- Sodium ion Na⁺
- 781 mg/kg
- Potassium ion K⁺
- 28.7 mg/kg
- Ammonium ion NH₄⁺
- 7.0 mg/kg
- Magnesium ion Mg²⁺
- 59.2 mg/kg
- Calcium ion Ca²⁺
- 167 mg/kg
- Manganese ion Mn²⁺
- 1.0 mg/kg
- Lead ion Pb²⁺
- < 0.05 mg/kg
- Strontium ion Sr²⁺
- 1.1 mg/kg
- Cadmium ion Cd²⁺
- < 0.005 mg/kg
- Total cations
- 1.0 mg/kg
Anions
- Fluoride ion F⁻
- 1.5 mg/kg
- Chloride ion Cl⁻
- 876 mg/kg
- Hydrogen sulfide ion HS⁻
- 6.0 mg/kg
- Thiosulfate ion S₂O₃²⁻
- 2.5 mg/kg
- Sulfate ion SO₄²⁻
- 253 mg/kg
- Bicarbonate ion HCO₃⁻
- 1068 mg/kg
- Bromide ion Br⁻
- 1.5 mg/kg
- Iodide ion I⁻
- 0.90 mg/kg
- Nitrate ion NO₃⁻
- 5.0 mg/kg
- Total anions
- 2.2 mg/kg
Undissociated Components
- Metasilicic acid H₂SiO₃
- 76.6 mg/kg
- Metaboric acid HBO₂
- 51.1 mg/kg
- Total undissociated
- 0.13 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- 141 mg/kg
- Free hydrogen sulfide H₂S
- 10.8 mg/kg
- Total dissolved gas
- 0.15 mg/kg
Totals
- Total dissolved substances
- 3.4 mg/kg
- Component total
- 3.5 mg/kg
Usage
- Heating
- No
- Dilution
- Yes（白湯の掲示『浴槽温度が高い期間（5〜11月）のみ加水しています』。秘湯の会『加水あり』。黒湯は通年加水、中の湯・滝の湯は7〜9月のみ加水（各掲示）。）
- Recycle / Filter
- No
- Additives
- No
- Disinfection
- No
Indications & Contraindications
- Bathing indications
- Atopic dermatitis, Plaque psoriasis, Chronic eczema, Epidermal suppuration, Cuts and grazes, Peripheral circulatory failure, Poor circulation, Depression, Xeroderma
- General indications
- High blood pressure (mild), Rheumatoid arthritis, Autonomic instability, Insomnia, Chronic pain or stiffness in muscles and joints, Muscle stiffness due to motor paralysis, Gastrointestinal dysfunction
- Contraindications
- Acute illness (especially with fever), Active tuberculosis, Malignant tumors, Severe heart disease, Respiratory failure, Renal failure, Bleeding disorders, Severe anemia, Any actively progressing illness, Pregnancy (especially early and late stages), Severe chronic dermatitis (sulphur springs)
Drinking
- Drinkability
- Not drinkable
