Recommended Ratio of Sodium Stearate for Water Drop Lip Stick Formulation
Question
I am looking to develop a moisturizing, colorless lip stick formulation that provides a fresh, watery, "water drop" sensation upon application. Since I plan to structure the stick using Sodium Stearate, what is the recommended optimal proportion of this ingredient, and what is a suitable starting formulation to achieve this high-water system effect?
Answer
The "water drop" lip stick formulation, structured by Sodium Stearate, is a specialized high-water system. Sodium Stearate works by forming a crystalline network within a solvent (water and glycols), which breaks upon application to release the liquid phase, giving the fresh, watery sensation.
Recommended Proportions for Sodium Stearate
For a stable lip stick with a high-water content and a "water drop" effect, the recommended starting proportion for Sodium Stearate is typically 5% to 8%.
- 5%: Will result in a softer stick, suitable for a very high-water release.
- 8%: Will result in a firmer, more stable stick, which is easier to mold and handle.
We recommend starting with 7% Sodium Stearate (such as Sodium Stearate (Powder, 10-15% Water)).
Key Components for the "Water Drop" Effect
To achieve the desired fresh, watery feel, the formula must contain a high percentage of humectants and water, which serve as the solvent for the Sodium Stearate.
| Component | Function | Recommended Range | Example Product |
|---|---|---|---|
| Sodium Stearate | Gelling/Structuring Agent | 5-8% | Sodium Stearate (Powder, 10-15% Water) |
| Water (Deionized) | Primary Solvent, Water Drop Effect | 40-50% | N/A |
| Humectants/Glycols | Co-Solvent, Hydration, Slip | 25-35% | Propylene Glycol (USP), Glycerin |
| Light Emollients | Lip Comfort, Non-greasy feel | 10-20% | Caprylic/Capric Triglyceride (e.q. Myritol 318) |
| Preservative | Essential for high-water formulas | 0.5-1.5% | Broad-spectrum system |
Example Starting Formula (100%)
This formula is designed to be colorless and provide a fresh, watery feel:
| Ingredient | % by Weight |
|---|---|
| Deionized Water | 45.0% |
| Propylene Glycol (USP) | 25.0% |
| Glycerin | 5.0% |
| Sodium Stearate (Powder, 10-15% Water) | 7.0% |
| Caprylic/Capric Triglyceride (e.q. Myritol 318) | 17.0% |
| Broad-Spectrum Preservative | 1.0% |
| Total | 100.0% |
Manufacturing Notes
- Heating: Combine the Water, Glycols, Glycerin, and Sodium Stearate. Heat the mixture to 75-85°C while stirring until the Sodium Stearate is completely dissolved and the mixture is clear.
- Oil Phase: Once clear, add the Caprylic/Capric Triglyceride and Preservative. Stir well.
- Pouring: Pour the hot, clear liquid into the lip stick molds immediately.
- Cooling: Allow the sticks to cool completely and solidify without disturbance (ideally at room temperature or in a refrigerator) before demolding. The final texture and stability depend heavily on the cooling process.
Related Products Mentioned
Propylene Glycol (USP)
