Understanding Pilling in Alcohol Hand Gel with Carbomer 940

Thank you for your question regarding pilling (forming flakes or "ขุย") in your alcohol hand sanitizer gel made with Carbomer 940.

Pilling can sometimes occur with gel formulations, particularly those using Carbomer polymers in high alcohol concentrations. Here's why this might be happening and how you can potentially address it:

• Film Formation: Carbomer is a polymer that creates a gel network when neutralized. As the alcohol and water evaporate from your hands, the polymer forms a thin film. If this film is too thick or brittle, it can break apart and peel off when you rub your hands, resulting in pilling.
• Concentration: Using too high a concentration of Carbomer 940 can lead to a more prominent and potentially brittle film, increasing the likelihood of pilling.
• Formulation Compatibility: While Carbomer 940 is widely used, the overall formulation, including the type and concentration of alcohol, neutralizer (such as Triethanolamine or AMP), and any other additives, can influence the final gel texture and film properties.
• Incomplete Neutralization: Proper neutralization of Carbomer is crucial for forming a stable gel. Incomplete neutralization can lead to an uneven structure that might contribute to pilling.

To minimize pilling, consider the following adjustments to your formulation or process:

1. Reduce Carbomer Concentration: Try lowering the percentage of Carbomer 940 used in your gel. Find the minimum concentration that still provides the desired viscosity.
2. Ensure Proper Neutralization: Make sure you are using the correct amount of alkali (like Triethanolamine or AMP) to fully neutralize the Carbomer to a pH between 6-7, as recommended for Carbomer 940. For formulations with high alcohol content, AMP is often recommended for better clarity.
3. Review Other Ingredients: If your formula contains other film-forming ingredients or incompatible substances, they could exacerbate the issue. Ensure all components are compatible.

By adjusting the Carbomer concentration and ensuring proper neutralization, you can often achieve a smoother gel that is less prone to pilling upon drying.