Formulation Review for Daily Exfoliating Pre-Serum

Here is a review of your proposed formulation for a daily exfoliating pre-serum:

Potential for Irritation

Your formula contains several exfoliating ingredients at notable concentrations for daily use:

• Linked Papain (5%): This enzyme exfoliates by breaking down proteins on the skin surface. 5% is at the higher end of the recommended usage range (1-5%).
• HEPES (4%): While primarily a buffer, HEPES also acts as a gentle exfoliant. 4% is at the higher end of the recommended range for gentle exfoliation (3-4%).
• FruitPeel (3%): This fruit extract blend provides gentle exfoliation. 3% is the recommended usage rate.
• Pumpkin Renew (5%): This ingredient acts like a gentle AHA. 5% is at the higher end of the recommended range for daily use (3-5%).
• Willow Bark Extract (5%): This natural source of Salicylic Acid exfoliates and has anti-inflammatory properties. 5% is within the range for accelerated cell turnover (5-10%).

The combination and concentrations of these multiple exfoliants, even those considered gentle, may still be too strong for daily application, especially for sensitive skin. While Allantoin (0.5%) is included to help reduce irritation, it might not be sufficient to counteract the cumulative effect of daily exfoliation from these ingredients.

Recommendation: Monitor your skin for signs of irritation (redness, dryness, stinging). If irritation occurs, consider reducing the frequency of use (e.g., every other day) or lowering the concentration of one or more of the exfoliating ingredients.

pH Suitability

The optimal pH range for the efficacy and stability of the exfoliating ingredients and Allantoin is generally between 5.0 and 6.5. Your formula includes HEPES at 4%, which is a buffer designed to maintain pH in the range of 5.0-6.5. This suggests the formula is intended to be within this suitable range.

Recommendation: You should measure the final pH of your formula to confirm it falls within the 5.0-6.5 range. If it is outside this range, you may need to adjust it using a dilute acid (like Lactic Acid or Citric Acid solution) to lower the pH or a dilute base (like Sodium Hydroxide solution) to raise the pH.

Texture for a Pre-Serum

With 66.5% distilled water as the base, and the inclusion of ingredients like VersaMoist (2%) and MOIST24 (5%), the formula is likely to have a light texture suitable for a pre-serum. VersaMoist helps enhance skin penetration and reduces stickiness, while MOIST24 improves texture, makes it feel soft and pleasant, and helps with faster absorption, all desirable characteristics for a pre-serum.

Conclusion: The texture should be appropriate for a pre-serum application.