Serum Formulation Analysis

Your chosen ingredients are well-suited for a brightening and anti-melasma serum.

• AHA (Alpha Hydroxy Acid): At 2%, AHA provides gentle exfoliation, helping to improve skin texture and reduce the appearance of dark spots and melasma over time.
• GlucoBright™ (Acetyl Glucosamine): This ingredient works synergistically with Niacinamide (B3) to target hyperpigmentation and improve skin tone. It also helps boost skin hydration by stimulating hyaluronic acid production.
• Safe-B3™ (Vitamin B3, Niacinamide): Niacinamide is a versatile ingredient known for its ability to reduce hyperpigmentation, strengthen the skin barrier, reduce redness, control oiliness, and improve skin texture. Using the Safe-B3™ type allows for higher concentrations (up to 10%) with less risk of flushing. Your concentration of 4% is within the effective range, especially when combined with Acetyl Glucosamine.
• Butylene Glycol: This acts as a solvent and humectant, helping to dissolve ingredients and add moisture to the serum. Your percentage of 2% is appropriate.
• WaterLube™ Soft (Cinnogel CG): This ingredient is a polymer designed to provide a smooth, non-sticky feel in water-based formulations and offer some moisturizing benefits. Your usage rate of 3.5% is within the recommended range (0.1-5.0%).
• Carbomer 940: This is a common gelling agent used to create gel textures in cosmetic formulations.

Addressing Your Questions

1. Should the formulation be adjusted for better results?
   The combination of GlucoBright and Safe-B3™ at 4% each is a good pairing for targeting hyperpigmentation based on research. AHA at 2% adds exfoliation benefits.

   For enhanced results, you could consider adding an antioxidant like Vitamin C (L-Ascorbic Acid or a stable derivative) or Ferulic Acid, which can further help with brightening and provide environmental protection. Adding a soothing agent like Allantoin or Panthenol could also be beneficial, especially with the inclusion of AHA, to minimize potential irritation.

2. Why did the texture become watery?
   The most likely reason your serum became watery even after adding Carbomer 940 is related to how Carbomer works and its compatibility with other ingredients in your formula, specifically AHA.

   • Carbomer Requires Neutralization: Carbomer is an acidic polymer that requires neutralization with an alkali (like Triethanolamine or Sodium Hydroxide) to swell and form a gel. If you added Carbomer to your water phase but did not add a neutralizing agent afterward, it would not thicken properly and remain liquid.
   • pH Sensitivity: Carbomer 940 is sensitive to low pH. Its gelling ability is significantly reduced or lost at a pH below 5. AHA is acidic, meaning it lowers the pH of your formulation. If you added Carbomer and then added AHA (or if the water phase was already acidic due to AHA), the low pH would prevent the Carbomer from gelling, even if you attempted to neutralize it later, or it could cause a gel that had formed to thin out.

   To achieve a gel texture with Carbomer 940:

   1. Disperse the Carbomer in the water phase first.
   2. Add your other water-soluble ingredients like GlucoBright, Safe-B3™, and Butylene Glycol.
   3. Add WaterLube™ Soft.
   4. Crucially, add a neutralizing agent (like Triethanolamine or Sodium Hydroxide solution) drop by drop while stirring until the gel forms and the desired viscosity is reached.
   5. After gelling, check the pH of the final formulation and adjust it to be within the optimal range for your active ingredients (e.g., 4.0-7.0 for Niacinamide and 3-7 for GlucoBright). Be aware that adjusting pH down after gelling with Carbomer can cause it to thin.

   If you need to formulate at a low pH (e.g., for higher concentrations of AHA or L-Ascorbic Acid), Carbomer 940 is not the ideal gelling agent. You would need to use an acid-tolerant thickener like Aristoflex AVC or Sepimax Zen.

Recommendations

1. Ensure you are neutralizing the Carbomer 940 with an alkali like Triethanolamine or Sodium Hydroxide after dispersing it in water and adding your other water-soluble ingredients.
2. Monitor and adjust the final pH of your serum to be in a range that is effective and stable for all your active ingredients (ideally between pH 4.0 and 7.0).
3. If you find it difficult to achieve a stable gel with Carbomer 940 due to the acidic nature of AHA or other ingredients, consider switching to an acid-tolerant gelling agent.