Maintaining Viscosity in Liquid Soap with High Fragrance Concentration
Question
When adding fragrance at a high concentration to a liquid soap formula containing surfactants like N8000, Prioly, and SLS, the viscosity decreases significantly. How can I maintain the desired viscosity in this formulation?
Answer
Adding fragrance to a liquid soap formula can sometimes decrease its viscosity, causing it to become too thin. This is because fragrances often contain solvents or oils that can interfere with the structure formed by the surfactants (like N8000, Prioly, and SLS) that provides the thickness.
To counteract this thinning effect when increasing the fragrance concentration, you can add a suitable thickener designed for surfactant-based systems like liquid soaps. Here are a few options:
- SugarThick™ (PEG-120 Methyl Glucose Dioleate): This is a plant-derived thickener that works well with most detergents and can help build viscosity in liquid soap formulas. It's easy to use and can also help reduce irritation from harsh surfactants. A typical usage rate is 1-5%.
- FoamThix™ Liquid (PEG-150 Pentaerythritol Tetrastearate (and) PEG-6 Caprylic/ Caprylic Glycerides (and) Water): This is another effective thickener for shampoos and liquid soaps. It is non-ionic, compatible with clear formulas, and provides a pleasant skin feel. It is typically used at 1-5%.
- FaceFoam-LC™ (Sodium Taurine Laurate/Corn Starch Modified/Lauric Acid/Myristic Acid): This is a liquid crystal thickener specifically for surfactants. It's known for its stable viscosity across different temperatures and does not negatively impact foam. It can be used at a rate of 0.1-20%, offering flexibility depending on how much thickening is needed.
You can try adding one of these thickeners gradually to your formula while stirring, starting with a low percentage (e.g., 1-2%) and increasing until you achieve the desired viscosity after adding the higher concentration of fragrance.
