HEC Settling in Sulfate-Free Shower Gel
Question
When formulating a sulfate-free shower gel using HEC as a thickener by heating water with surfactant and glycerin at 70°C, adding HEC, then adding fragrance dissolved in butylene glycol, the HEC settles after 2 hours instead of forming a uniform gel. What is the cause and how can this be fixed?
Answer
HEC Gel Settling Issue in Sulfate-Free Shower Gel
The issue of Hydroxyethyl Cellulose (HEC) settling at the bottom and not forming a uniform gel is likely due to the mixing method, specifically adding HEC into a solution already containing surfactant and glycerin at high temperature.
HEC needs proper hydration in water to form a gel. Surfactants, especially at higher temperatures, can sometimes interfere with this hydration process, causing the HEC particles to clump together or not swell correctly, leading to sedimentation.
Recommended Solution:
To ensure proper gel formation with HEC, it is best to hydrate the HEC in plain water first before adding other ingredients like surfactants, glycerin, or fragrance.
Here is a suggested revised method:
- Heat the required amount of DI Water to approximately 70°C.
- While stirring the hot water continuously, slowly sprinkle the HEC powder into the water. It is crucial to add the powder slowly while stirring vigorously to prevent clumping.
- Continue stirring until the HEC is completely dissolved and a clear, uniform gel is formed. This may take some time.
- Allow the HEC gel to cool down.
- Once the gel has cooled, gently mix in the surfactant, followed by glycerin.
- In a separate container, dissolve the fragrance in Butylene Glycol.
- Slowly add the fragrance/Butylene Glycol mixture to the main gel mixture, stirring until fully incorporated.
- Ensure all ingredients are well mixed and the gel is uniform before letting it sit.
This method allows the HEC to hydrate correctly in water without interference from other components, leading to a stable and uniform gel texture.
