Vitamin C in Foam Cleanser Formulations

When formulating a foam cleanser with Vitamin C, it's important to consider the stability of the Vitamin C in a water-based product with a typical cleanser pH.

While L-Ascorbic Acid is a potent form of Vitamin C, it is highly unstable in water and requires a low pH (typically 2.0-4.0, with FDA recommending at least 3.5 for leave-on products). This low pH can be irritating in a wash-off product like a cleanser, and maintaining stability is challenging.

For a foam cleanser, stable Vitamin C derivatives are generally more suitable. Two good options are:

• Ascorbyl Glucoside (AA-2G): This form is stable in water and effective for brightening and antioxidant benefits. It is stable in a pH range of 6.5-6.8. The recommended usage rate is 2-10%.
• Sodium Ascorbyl Phosphate (SAP): This is another highly stable, water-soluble Vitamin C derivative, particularly effective for whitening. It is stable in a pH range of 7-9. The recommended usage rate is 0.5-10% (with 3% being a common recommendation).

To achieve a noticeable brightening effect in a wash-off product like a cleanser, you can use a concentration towards the higher end of the recommended range for the chosen stable form (AA-2G or SAP), while ensuring the final formula pH is within the stable range for that specific ingredient. Always adhere to the maximum recommended percentage to avoid potential issues with solubility or irritation.

Remember that the effectiveness in a wash-off product might be less pronounced compared to a leave-on serum due to the short contact time with the skin.