Science
Mechanism of Action
This ingredient operates primarily as a viscosity-increasing agent, effectively thickening cosmetic formulations to achieve a smoother, softer, and more gel-like consistency. It functions as an emulsion stabilizer, preventing the separation of oil and water phases, thereby ensuring product uniformity and stability across a wide temperature range (-30°C to 50°C). Beyond stabilization, it significantly enhances texture, improving spreadability and imparting a light, silky, non-greasy feel to formulations. Its humectant and moisture-retaining properties aid in maintaining skin hydration by forming a protective barrier that minimizes transepidermal water loss. The starch-based structure can also absorb excess oils, contributing to a mattifying effect in specific product types. Additionally, it acts as a bulking agent, increasing product volume, and assists in the uniform distribution of other active ingredients on the skin.
Research
Clinical Evidence
High confidenceTypical usage concentrations vary by product type; the CIR recommends 3-10% for general cosmetic use.
Transparency
Dusting Analysis
The Formula
Formulation
Stability
Stable within emulsion systems and formulas across a pH range of 3-9. Emulsions containing this ingredient exhibit exceptional stability from -30°C to 50°C. It is dispersible in cold water and compatible with oils, allowing for 'one-pot processing'. Due to its non-ionic nature, it shows broad compatibility, including with up to 20% mono- and divalent salts. While heat is not required for initial blending in water, it can be applied in subsequent steps. However, high pH levels may diminish performance, and long-term stability can be compromised by extended exposure to heat, moisture, or UV radiation.
Synergies
- Compatible with high concentrations of mono- and divalent salts (up to 20%) due to its non-ionic character.
Conflicts
- Sensitive to high pH levels, which may lead to diminished performance.
- Its barrier-forming capacity may, in some instances, impede the absorption of certain active ingredients, such as exfoliants.
Safety
Safety Profile
The Expert Panel for Cosmetic Ingredient Safety (CIR) deemed Sodium Hydroxypropyl Starch Phosphate safe for cosmetic use within current practices and concentrations, recommending concentrations between 3% and 10%. While generally mild and non-irritating, it has been noted as a mild ocular irritant in one study. Allergic reactions are extremely rare.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Sodium Hydroxypropyl Starch Phosphate is a valuable ingredient for precision skincare, offering superior texture enhancement and robust formula stabilization with a low risk of irritation or comedogenicity, making it suitable for all skin types.
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