Preservative for BHA Toner with Encapsulated Salicylic Acid

Regarding your question about adding Phenoxyethanol to your BHA toner formulation using Encapsulated Salicylic Acid:

The observation that the INCI list of the Encapsulated Salicylic Acid ingredient includes "preserved by Phenoxyethanol" is correct. This indicates that the raw material itself contains Phenoxyethanol to maintain its stability and prevent microbial growth within the ingredient. However, this does not mean that your final toner formulation, which is largely water-based (92% water), is adequately preserved.

Water-based cosmetic formulations require a preservative system to prevent the growth of bacteria, mold, and yeast that can be introduced during manufacturing and consumer use. The small amount of Phenoxyethanol present within the 8% Encapsulated Salicylic Acid ingredient is typically not sufficient to preserve the entire 100% of your final toner product.

Therefore, yes, you still need to add a preservative to your toner formulation. Phenoxyethanol is a suitable and common preservative for this type of product.

To avoid potential irritation while ensuring adequate preservation, you should add Phenoxyethanol (or a blend containing it) to achieve a total concentration that is effective but within recommended usage rates. The typical recommended usage rate for Phenoxyethanol as a preservative in a final cosmetic product is between 0.5% and 1.0%.

When calculating the amount to add, you can consider the small amount already present from the Encapsulated Salicylic Acid, but the primary preservation will come from the additional amount you incorporate into the water phase. Aim for a total concentration (including the amount from the encapsulated ingredient) within the 0.5% to 1.0% range for effective preservation.

Using Phenoxyethanol at these standard concentrations is generally well-tolerated, although individual sensitivity can vary. Since your skin tolerates BHA well, using a standard level of Phenoxyethanol for preservation should also be acceptable, provided you don't exceed the recommended total concentration.

In summary, the Phenoxyethanol in the Encapsulated Salicylic Acid preserves the ingredient itself. You must add a preservative, such as Phenoxyethanol, to your final toner formulation to ensure the stability and safety of the entire product.