Preservative for Encapsulated Salicylic Acid Solution

For your formulation of Encapsulated Salicylic Acid (Liquid, Timed-Release) 6.6% and Water 93.4%, which is a water-based product, it is generally recommended to add a preservative to prevent microbial contamination and ensure product stability and safety.

While Salicylic Acid itself has some antimicrobial properties, especially at certain pH levels, it may not be sufficient to fully protect the product from microbial growth over time, particularly in a dilute aqueous solution.

If you are making this product for personal use and plan to use it up quickly (within a few months), you might choose not to add a preservative, as suggested in the thread. However, for best practice and safety, adding a preservative is still advisable.

If you are developing this formula for commercial production and sale, adding a suitable preservative is essential to ensure product safety and shelf life under various storage conditions.

Based on the discussion, Mild Preserved Eco is suggested as a suitable preservative. You can add it at a recommended usage rate, such as 1% as mentioned in the thread.