Salicylic Acid Formulation Questions

Here are the answers to your questions regarding formulating with Salicylic Acid products:

1. Encapsulated Salicylic Acid (Wash-Off) as a Leave-On?

The product "Encapsulated Salicylic Acid (Liquid, Timed-Release, Wash-Off)" is specifically designed for wash-off applications, such as cleansers. While it is gentler than standard Salicylic Acid and has a pH closer to skin pH during its release, it is not recommended for leave-on products. For leave-on formulations using an encapsulated Salicylic Acid, you should choose a product specifically labeled for leave-on use, such as "Encapsulated Salicylic Acid (Liquid, Timed-Release, Leave-On)" or the powder type. "Salicylic Acid EZ" is suitable for leave-on applications despite its lower pH because its formulation is designed for this purpose.

2. Thickeners for Salicylic Acid Products

To create a gel with "Encapsulated Salicylic Acid (Liquid, Timed-Release, Wash-Off)", you can use Hydroxyethyl Cellulose or Hydroxypropyl Methylcellulose (HPMC), or other non-ionic thickeners. This product is incompatible with "Pro Polymer".

For "Salicylic Acid EZ", "Pro Polymer" is a suitable gel maker, as shown in example formulations. While Hydroxyethyl Cellulose might also work, Pro Polymer is a tested option for Salicylic Acid EZ.

3. Preservatives

Water-based formulations generally require a preservative system to prevent microbial growth and ensure product safety and shelf life.

"Encapsulated Salicylic Acid (Liquid, Timed-Release, Wash-Off)" contains Phenoxyethanol as a preservative within the ingredient itself. However, your final formulation will still need a complete broad-spectrum preservative system to protect the entire product.

"Salicylic Acid EZ" does not contain a preservative. Therefore, any formulation using Salicylic Acid EZ will require the addition of a suitable broad-spectrum preservative system.

Refrigeration can help extend the life of products but is typically not sufficient on its own for long-term preservation of water-based cosmetic formulations. It is best practice to include a reliable preservative system. You should choose a broad-spectrum preservative system that is compatible with the other ingredients in your formula and effective at the final product's pH.