Evaluation of Your Eye Serum Formula

Your proposed eye serum formula is very interesting and shows a good understanding of selecting active ingredients specifically for the delicate eye area. The combination of ingredients targets key concerns like dark circles, puffiness, and skin firmness.

Let's break down the ingredients and their roles based on the product information:

• REGU-AGE: This ingredient is specifically designed for eye care. It is known to effectively reduce dark circles and under-eye puffiness, while also helping to strengthen and firm the skin around the eyes. Your usage rate of 5% is within the recommended range for good efficacy.
• Vitamin B3 (Niacinamide): A versatile vitamin that helps reduce hyperpigmentation (red/dark spots), improves skin hydration by stimulating collagen and ceramide production, strengthens the skin barrier, and can increase blood circulation. This increased circulation can help address dark circles caused by poor blood flow. Your 2% concentration is appropriate and within the suggested range.
• NAG (Acetyl Glucosamine): Works synergistically with Vitamin B3 to brighten skin tone and reduce dark spots. It also encourages the skin's natural production of Hyaluronic Acid, leading to improved hydration and reduced fine lines. Your 4% usage aligns with the recommendation to use it with Niacinamide.
• Hyaluronic Acid (Standard Molecule and Nano Molecule): Using two molecular weights of Hyaluronic Acid is beneficial. The standard molecule provides surface hydration and contributes to the serum/gel texture, while the nano molecule penetrates deeper for hydration at lower skin layers and offers anti-aging benefits. Your total of 1% (0.5% Standard + 0.5% Nano) provides good hydration.
• Butylene Glycol: Acts as a humectant to attract and retain moisture, and also functions as a solvent. 10% is a common and effective concentration in serums.

Key Consideration and Recommendations:

1. Preservative Incompatibility (Eye Preserved) with Hyaluronic Acid: Based on the product information for Eye Preserved (Polyhexamethylene Biguanide, PHMB), it is incompatible with all anionic ingredients, including all types of Hyaluronic Acid. Using Eye Preserved in a formula with Hyaluronic Acid will lead to instability, potential precipitation, and reduced efficacy of the ingredients. You must switch to a different preservative that is compatible with Hyaluronic Acid, such as Phenoxyethanol or other preservatives specified as compatible with anionic ingredients.
2. Mixing Procedure: Your mixing steps need some adjustments to ensure proper dissolution of ingredients and maintain their efficacy:
   • Hyaluronic Acid powders (both Standard and Nano) should be dissolved in water first. This requires time for hydration, often several hours in the refrigerator, or using a high-speed mixer. Vigorous shaking alone may not fully dissolve the powder and can introduce air bubbles.
   • Water-soluble ingredients that are heat-stable, such as Vitamin B3, NAG, and Butylene Glycol, can be added to the water phase along with or after the Hyaluronic Acid has fully hydrated.
   • REGU-AGE should be added in the final step when the formula has cooled down (below 40°C) as it is sensitive to high temperatures.
   • The preservative (a compatible one) should also be added in the final step.
3. Achieving a Gel Texture: As suggested by C7, making the serum a gel can improve usability. Your current formula with 1% total Hyaluronic Acid might be a light serum. To achieve a thicker gel texture, you could slightly increase the total Hyaluronic Acid concentration (staying within recommended limits) or incorporate a compatible gelling agent. If using a gelling agent, ensure it is compatible with your chosen preservative and other ingredients (e.g., an electrolyte-tolerant gelling agent if needed).

Revised Mixing Procedure Suggestion (after changing the preservative):

1. Dissolve Hyaluronic Acid Standard and Nano in the water phase. Stir or blend to disperse, then refrigerate for at least 3 hours or until fully dissolved and a clear gel forms.
2. Once Hyaluronic Acid is dissolved, add Butylene Glycol, Vitamin B3, and NAG. Stir until fully dissolved.
3. Add the compatible preservative and mix well.
4. When the formula temperature is below 40°C, add REGU-AGE and stir gently until incorporated.
5. If using a gelling agent, add it according to its specific instructions at the appropriate step.

Your ingredient selection is excellent for targeting eye area concerns. By addressing the preservative incompatibility and adjusting the mixing procedure, you can create an effective and stable eye serum.