Formulating a Toner for Blackheads with Encapsulated Salicylic Acid and Vitamin C

Question

I am developing a product to address blackheads and have two potential formulations I'd like to ask about:

Formulation 1: Encapsulated Salicylic Acid 3.3% + Vitamin C (L-ascorbic acid) 15% + Water
Formulation 2: Encapsulated Salicylic Acid 3.3% + Water

My questions are:

Is Formulation 1 viable? I am concerned about the stability of L-ascorbic acid in water.
Is Formulation 2 viable? If so, are there any necessary additions, such as a preservative?
For targeting blackheads specifically, are these formulations suitable, or are other ingredients required?
Should I use the 'Leave-On' or 'Wash-Off' type of Encapsulated Salicylic Acid for a product intended to stay on the skin?

MySkinRecipes Expert · Accepted Answer

Formulation Advice for Blackheads

Based on your proposed formulations and the expert advice:

The formulation using Encapsulated Salicylic Acid 3.3%, Vitamin C (L-ascorbic acid) 15%, and water is not recommended. L-Ascorbic Acid is unstable when mixed directly with water.
The formulation using Encapsulated Salicylic Acid 3.3% and water is possible, but you must add a preservative.
A suitable preservative is Phenoxyethanol at a concentration of 1%.
If your focus is solely on addressing blackheads, you do not necessarily need to add other ingredients beyond the Encapsulated Salicylic Acid, water, and preservative.
Ensure you are using a grade of Encapsulated Salicylic Acid suitable for leave-on cosmetic products, as the "Wash-Off" type is intended for products like cleansers.

Recommended Simple Toner Formulation for Blackheads:

This formulation should be effective for targeting blackheads.