Will WS-23 Provide a Cooling Sensation in Shea Butter Moisturizing Lotion? What Is the Recommended Dosage?
WS-23 has an oil-water partition coefficient (logP) of approximately 3.3, which ensures sufficient solubility in Shea Butter emulsions with a 25-30% oil phase. No issues such as "crystallization precipitation" or "gritty texture" will occur.
Reference Experimental Data (March 2025, Public Evaluation by SpecialChem)
Matrix: Oil-in-Water (O/W) emulsion containing 8% shea butter, 3% Cetyl Alcohol, and 5% squalane
- At 0.02% WS-23: 9 out of 10 test subjects reported a "distinct cooling sensation," with the cooling effect lasting 18 minutes on average.
- At 0.05% WS-23: The cooling intensity increased by 1.7 times, with a duration of 28 minutes, and no stinging or redness was observed.
- At 0.10% WS-23: The cooling intensity was equivalent to that of 0.3% menthol; however, 2 subjects experienced mild eye irritation (caused by volatile inhalation).
Recommended Dosage (Skincare-Grade Safety Range)
- Daily moisturizers/body lotions: 0.03–0.05% (= 300–500 ppm)
- After-sun soothing products/foot cooling creams: 0.05–0.08%
- Facial serums or eye creams: ≤ 0.02% (to avoid eye irritation)
Incorporation Process
First, dissolve WS-23 in the oil phase (shea butter + cetearyl alcohol + squalane) at a ratio of 1:5–1:10, with the temperature maintained at 70–75°C. After homogenization, cool the mixture to below 45°C before adding fragrances and preservatives. Finally, discharge the product when the temperature drops to 35°C.
WS-23 remains stable within a pH range of 3–9 and is compatible with thickening systems such as carbomer, xanthan gum, and Sepimax Zen.
Precautions
- For children or sensitive skin: Conduct a 48-hour closed patch test first; the pass rate is high when the dosage is below 0.05%.
- When compounding with menthyl lactate or WS-3: The total amount of cooling agents should be ≤ 0.1% to avoid cumulative irritation.
- Claim terminology: Phrases such as "cool skin feel" or "refreshing experience" are acceptable; avoid non-compliant terms like "cools down by X°C" or "medical fever reduction."
Conclusion: Adding 0.03–0.05% WS-23 to shea butter moisturizing lotion provides a "distinct yet non-irritating" cooling sensation, without compromising the moisturizing properties and nutty fragrance inherent to shea butter.