Shower Gel Texture and Stability Issues: Stringiness and Precipitation
Question
I am developing a shower gel formulation using the following ingredients:
- Baby Foam™ (Sodium Cocoyl Isethionate)
- Cocamidopropyl Betaine
- Decyl Glucoside
- Lauryl Glucoside
The total concentration of the surfactants is 45%. When I warm the glucosides for mixing, the mixture forms a gel. However, I am encountering two issues:
- When the mixture is diluted with water, the texture becomes stringy or mucus-like.
- Over time, white cloudy particles settle at the bottom of the container.
Could you please advise on the potential causes of these issues and how to resolve them?
Answer
Understanding the Shower Gel Texture and Stability Issues
Thank you for providing details about your shower gel formulation and the issues you are encountering. The problem you described, where the mixture becomes stringy/mucus-like when diluted and develops white cloudy particles over time, is likely related to the interaction and solubility of the surfactants you are using, particularly the Baby Foam™ (Sodium Cocoyl Isethionate).
Based on the properties of the ingredients:
- Baby Foam™ (Sodium Cocoyl Isethionate): This is an anionic surfactant known for its mildness and foam. However, it is also noted that it can easily precipitate if in liquid gel formulations. The appearance of white cloudy particles settling at the bottom is a strong indication that the Sodium Cocoyl Isethionate is precipitating out of the solution over time.
- Cocamidopropyl Betaine: This is an amphoteric surfactant that is generally compatible with other surfactant types and helps with foam and texture.
- Decyl Glucoside and Lauryl Glucoside: These are non-ionic surfactants. While gentle, they can be viscous and may require warming to mix properly, which you are already doing. Their high inherent pH also needs consideration in the overall formula.
The combination of anionic, non-ionic, and amphoteric surfactants can create complex interactions that affect viscosity and stability. The high total concentration of surfactants (45%) in your formula also contributes to the complexity.
The stringy texture observed upon dilution might be a result of the specific micellar structures formed by this surfactant blend, potentially linked to the solubility or compatibility issues leading to the precipitation.
The product description for Baby Foam™ specifically recommends including Disodium EDTA 0.1% in formulas to help prevent it from hardening or settling. Its absence in your formula could be a contributing factor to the precipitation issue.
The staff has informed you that your specific formula and process will be tested by R&D, which is the best way to identify the exact cause and find a tailored solution. They will be able to determine if adjusting the surfactant ratios, pH, mixing method, or adding a chelating agent like Disodium EDTA is necessary to achieve a stable and desirable texture.
We appreciate your patience as the R&D team investigates your formulation.
