Formula Evaluation for Combination Skin

Let's evaluate your proposed formula for combination skin with oiliness, dullness, clogged pores, and acne breakouts, considering your goals of brightening and reducing acne.

Your formula includes several beneficial ingredients:

• Zinc PCA: Excellent for controlling oiliness and supporting acne healing.
• Vitamin B3 (Niacinamide): At 4%, Niacinamide is great for reducing oil, minimizing pores, improving skin tone and dullness, strengthening the skin barrier, and has anti-inflammatory properties beneficial for acne. It also works synergistically with Acetyl Glucosamine for brightening.
• Glucosamine (N-acetyl-D): Aids in brightening, reducing dark spots, gentle exfoliation, and boosting skin hydration.
• Vitamin C (L-ascorbic acid): A powerful antioxidant for brightening and collagen support.
• Glutathione: An effective antioxidant that also helps with skin brightening.
• Disodium EDTA: Improves formula stability.

Considerations and Recommendations

Based on your skin type and concerns, and the feedback received, here are some points to consider:

1. Gel Base: As advised, Hyaluronic Acid Gel may feel heavy on combination skin. Using a gel maker like Pro Polymer is recommended for a lighter, more suitable texture.
2. Clogged Pores: While your formula addresses oiliness, it lacks an ingredient specifically for dissolving clogged pores. Adding Salicylic Acid (BHA) would be highly effective for this purpose as it exfoliates within the pores.
3. Vitamin C Stability and pH: Using 15% L-ascorbic acid is potent for brightening but is unstable in water and requires a low pH (3.5-4.0). This low pH can be irritating and conflicts with the optimal pH ranges of Niacinamide and Zinc PCA, potentially reducing their efficacy and stability. Glutathione also has specific pH requirements (3-6).

Suggested Adjustments

To create a more stable, less irritating, and effective formula for your skin type:

• Replace Double Hyaluronic Gel with Pro Polymer as the base.
• Include Salicylic Acid (e.g., 0.5-2%) to target clogged pores.
• Consider using a lower concentration of L-ascorbic acid or switching to a more stable Vitamin C derivative like Ethyl Ascorbic Acid or Ascorbyl Glucoside. These alternatives are easier to formulate, more stable at a pH compatible with Niacinamide and Zinc PCA, and still provide excellent brightening benefits with less irritation risk.

A formula using Pro Polymer as the base, incorporating Salicylic Acid, and utilizing a stable Vitamin C derivative would be better suited for your combination skin, effectively addressing oiliness, clogged pores, acne support, and brightening concerns.