Formula Review for Hydrating and Brightening Serum

Thank you for sharing your serum formula aimed at hydration, reducing dark spots, reducing melanin, reducing inflammation, and brightening. The ingredients you've selected are suitable for these purposes.

Let's review the percentages in your formula:

• Total Percentage: Your current formula adds up to 100.5%. You will need to reduce the DI water percentage by 0.5% to make the total exactly 100%.

• DI (Deionized Water): Adjust to 72%.

• Hyaluronic Acid (0.5%): This percentage is suitable for providing hydration to the skin. Different molecular weights of Hyaluronic Acid offer hydration at different skin depths.

• Vitamin B3 (Niacinamide) (6%): Niacinamide is excellent for brightening, reducing inflammation, and improving skin barrier. While some high-purity grades like Safe-B3™ or Extreme-B3™ can be used up to 10%, 6% is slightly above the generally recommended 5% for minimizing potential irritation, especially for sensitive skin. You might consider reducing this to 3-5% to balance efficacy and comfort, although 6% might be tolerated depending on the specific grade and individual.

• Vitamin B5 (Panthenol) (2%): This is a good percentage for hydration, soothing, and supporting skin repair. It works well with other hydrators.

• Arbutin (2%): For Alpha Arbutin, 2% is the maximum recommended usage rate for skin brightening and reducing dark spots. This percentage should be effective.

• Glycerin (1%): Glycerin helps attract and retain moisture. 1% is a bit low; increasing it slightly (e.g., to 2-5%) could enhance hydration and texture, though higher amounts can feel sticky.

• Centella Asiatica Extract (Madecassoside 90%) (5%): The recommended usage rate for this high-concentration extract is typically 0.1-2%, with 1% being commonly recommended. Using 5% is significantly higher than recommended and may lead to solubility issues in a water-based formula, as the product description notes limited solubility in water (not more than 1.0% w/v). It might not provide proportionally greater benefits and could affect formula stability and appearance. It is strongly recommended to reduce this percentage to 1-2%.

• Tetrahydrodiferuloylmethane (WhiteCumin™) (5%): The recommended usage rate for WhiteCumin™ is 0.1-1.0%, with 0.2% recommended. 5% is extremely high and far exceeds the recommended maximum. This ingredient is soluble in Glycol, Propanediol, and oil, and requires a solvent like Glycol or Polysorbate 20 to dissolve before adding to the main formula. Using 5% will almost certainly cause significant solubility and stability problems in a water-based serum and is unlikely to be effective or safe at such a high concentration. It is strongly recommended to reduce this percentage to 0.1-1.0%.

• Artocarpus Lakoocha Wood Extract (Oxyresveratrol 98%) (5%): The recommended usage rate for this extract is 0.1-0.5%. 5% is also extremely high and far exceeds the recommended maximum. This ingredient is soluble in Glycol and requires stabilizers for long-term stability (Sodium Metabisulphite, Disodium EDTA, antioxidants, UV protection if in a clear bottle). Using 5% will cause major solubility and stability issues. It is strongly recommended to reduce this percentage to 0.1-0.5%.

• Mild Preservative (1%): This percentage is within the typical recommended range (0.75-1.5%) for Mild Preserved™ COS.

Recommended Adjustments Summary:

• Reduce DI Water to 72%.
• Consider reducing Vitamin B3 (Niacinamide) to 3-5%.
• Strongly reduce Centella Asiatica Extract to 1-2%.
• Strongly reduce Tetrahydrodiferuloylmethane to 0.1-1.0%.
• Strongly reduce Artocarpus Lakoocha Wood Extract to 0.1-0.5%.
• Consider slightly increasing Glycerin to 2-5% for enhanced hydration and texture.

After adjusting the percentages, it is crucial to perform stability testing on the formula (checking for separation, color change, clarity over time and under different temperatures) and patch testing on your skin to ensure there is no irritation before using the product widely.