Sulfate-Free Shampoo Thickening Issue

Subject: Re: Shampoo Formulation Advice

Hello,

Thank you for sharing your shampoo formula and the issue you're facing with thickening.

It's common for sulfate-free shampoo systems, especially those based on non-ionic or amphoteric surfactants (like Cocamidopropyl Betaine), not to thicken effectively with Sodium Chloride (NaCl) or salt. Salt thickening primarily works well with anionic surfactants like sulfates (e.g., SLES, SLS).

Your formula uses a "Sulfate free No-Tear Shampoo Base" and Cocamidopropyl Betaine. It's likely that the surfactant system in your base is not responsive to salt.

To thicken a sulfate-free shampoo like yours, you typically need to use different types of thickeners. Common thickeners for sulfate-free systems include:

• Cellulose derivatives: Such as Hydroxyethylcellulose (HEC) or Hydroxypropylcellulose (HPC).
• Natural gums: Like Xanthan Gum or Guar Gum.
• Acrylates copolymers: Various types designed for thickening surfactant systems.
• PEG derivatives: Such as PEG-120 Methyl Glucose Dioleate or PEG-150 Distearate.

Recommendations:

1. Check the Shampoo Base Specifications: The best approach is to check the technical data sheet or supplier information for the "Sulfate free No-Tear Shampoo Base" you used. The supplier usually provides recommendations on how to thicken their specific base and which thickeners are compatible and effective.
2. Consider Alternative Thickeners: If the base information isn't helpful, you might need to experiment with small amounts of the alternative thickeners mentioned above. Start with low percentages (e.g., 0.1% to 0.5% for gums or cellulose derivatives, higher for PEG derivatives depending on the type) and add gradually while stirring until the desired viscosity is reached. Note that different thickeners require different methods of incorporation (some need to be dispersed in water first, some added to the surfactant phase, some require heating).

Adding more salt is unlikely to solve the thickening issue in this specific formula and might even cause thinning or other stability problems.

I hope this explanation helps! Good luck with your formulation.