Formulating a PHA Serum with Hyaluronic Acid Base: Troubleshooting Pilling and Ingredient Stability

Hello,

Regarding your question about formulating a PHA serum:

You are correct that the pilling issue you experienced with your first formula (using Propolymer Silk) when layering a hyaluronic acid product on top is likely due to the incompatibility of Propolymer Silk with gel bases like hyaluronic acid.

Yes, you can mix PHA directly into a hyaluronic acid base. This should help prevent the pilling issue you encountered.

Regarding your proposed formula using hyaluronic acid:

1. Hyaluronic Acid Concentration: Your proposed total concentration of 1% (0.5% Hya standard + 0.5% Hya Nano) might feel quite sticky on the skin for some users. If you haven't used hyaluronic acid at this concentration before, it's recommended to start with a lower concentration, such as 0.1% total hyaluronic acid, and adjust based on your preference.
2. Allantoin Solubility: Dissolving Allantoin 0.4% in warm water works, but when the solution cools down (especially if refrigerated), Allantoin's solubility decreases, and it might precipitate out. To ensure stability and prevent precipitation, it's safer to use a lower concentration, around 0.2%.
3. Phenoxyethanol Concentration: PHA itself has good antimicrobial properties. Therefore, a Phenoxyethanol concentration of 1% is higher than necessary. You can reduce the concentration to 0.5%, which should be sufficient for preservation.

Based on these points, here is an adjusted formula you could consider:

• PHA: 5%
• Hya standard + Hya Nano: 0.1% - 1% total (start lower if unsure about texture preference)
• Phenoxyethanol: 0.5%
• DI water: Adjust amount based on other ingredients (e.g., if total Hya is 0.1%, water would be ~94.4%)
• Allantoin: 0.2% (dissolved in the water phase)

Method:

1. Heat the DI water and dissolve Allantoin. Let cool completely.
2. Add PHA and stir until dissolved.
3. Add Hya standard and Hya Nano and stir/mix until fully dissolved and gel forms. You can refrigerate during this step to help the Hya dissolve faster.
4. Add Phenoxyethanol and stir to combine.

This formula using a hyaluronic acid base should provide a more compatible texture for layering other hyaluronic acid products and help address the pilling issue.