Making 10% AHA Gel with Glycolic Acid and Aloe Gel: Stability and Texture Issues
Question
I want to make a 10% AHA gel using 70% Glycolic Acid and an existing Aloe Vera Gel base.
My calculation is to mix `14.28g` of `70% Glycolic Acid` with `85.72g` of `Aloe Vera Gel`.
I am concerned about the stability of ingredients like Panthenol, the thickening ability of Pro Polymer, and the effectiveness of Phenoxyethanol at the expected low pH (around 3).
Is this mixing method feasible? How can I adjust the viscosity if the resulting gel is too thin?
Answer
Hello, thank you for your detailed question and for researching the topic thoroughly!
Your calculation for making a 10% AHA gel using 70% glycolic acid and Aloe Vera Gel is correct. Mixing 14.28g (or approximately 14g) of 70% glycolic acid with 85.72g (or approximately 86g) of Aloe Vera Gel will yield a 10% AHA concentration.
Regarding your concerns about ingredient stability at the expected low pH (~3):
- Panthenol: As mentioned in the replies, Panthenol's stability decreases below pH 4. However, it might still be acceptable for short-term use (e.g., within a month), similar to how it's used in some commercial products like Skinceutical C E Ferulic which has a low pH. True stability over time would require testing.
- Pro Polymer: You are correct that Pro Polymer's thickening ability is reduced at low pH. However, it still works and you can achieve the desired viscosity by simply increasing the amount of Pro Polymer used.
- Phenoxyethanol: While some information suggests Phenoxyethanol works best from pH 4 upwards, other sources claim stability from pH 2-12. More importantly, the high acidity of the AHA solution itself acts as a strong preservative, inhibiting bacterial growth even if the Phenoxyethanol's efficacy is reduced. So, adding it is generally safe.
Your plan to simply mix the 70% Glycolic Acid with the existing Aloe Vera Gel is a valid approach, especially for a beginner. As the staff mentioned, if you find the resulting gel too thin, you can adjust the consistency by adding Pro Polymer.
Regarding your suggestion about the Vitamin C E Ferulic Pre-Mix Kit packaging: While amber glass is traditionally recommended for light-sensitive ingredients like Vitamin C, modern opaque plastic bottles can also provide adequate protection from light. Additionally, the plastic used for packaging these types of products is typically selected to be acid-resistant, suitable for the low pH of Vitamin C serums.
We appreciate your feedback and suggestion for adding more pre-mix kits!