Formulation Compatibility Assessment

Your formulation includes a comprehensive set of ingredients targeting moisturizing, skin tightening, wrinkle reduction, and whitening, along with an exfoliant. This is a good approach to address multiple skin concerns.

However, there are several potential compatibility issues and points to consider regarding the mixing process and ingredient concentrations:

Potential Compatibility Issues

1. Sym-White and Amino Acids/Proteins: The description for Sym-White (Phenylethyl Resorcinol) explicitly states to avoid ingredients from the Amino Acid, Urea, or protein groups, as they can cause yellowing or separation. Your formula includes Wrinkle-Fill (Acetyl-Tyrosine, an amino acid derivative) and Glycosaminoglycans Complex, which falls under the category of protein/sugar complexes. Combining Sym-White with these ingredients is likely to cause instability, discoloration, or reduced efficacy of the Sym-White.
2. pH Level: Sym-White requires a final formula pH of 4-5 for stability. Wrinkle-Fill (Acetyl-Tyrosine) is acidic (pH 2-3 at 2.5%). Including both will require careful pH adjustment to be within the 4-5 range for Sym-White, while also ensuring the overall formula is stable and not too irritating for the skin. The optimal pH for the other actives and the preservative also needs to be considered.
3. Preservative Compatibility: The specific preservative you plan to use at 0.7% is not identified. Preservatives have specific pH ranges and compatibility requirements. You must ensure your chosen preservative is effective and stable at the target pH of 4-5 and compatible with all other ingredients, especially the actives and the emulsifier.

Mixing Process and Temperature

• Sensitive Cream Maker: The description indicates this emulsifier melts around 70°C. Your Part B hot process is listed at 50°C, which may not be sufficient for proper melting and emulsification. Consider increasing the hot process temperature for Parts A and B to around 70-75°C.
• Heat-Sensitive Ingredients: Several ingredients in your Part C and Part D, namely Palmaria Palmata Extract, Glycosaminoglycans Complex, HydroAlgae, and Encapsulated Salicylic Acid, should not be exposed to temperatures above 40°C. Your current process of adding Part C and D after the hot process is correct, but ensure the emulsion has cooled sufficiently (below 40°C) before adding these ingredients.
• Pure-Baicalin Mixing Phase: Pure-Baicalin should be mixed in the water phase and avoids heat above 60°C. It is currently listed in Part B (oil phase). It should be moved to Part C and added during the cool-down phase along with other heat-sensitive water-soluble ingredients.
• Encapsulated Salicylic Acid Dispersion: This is a powder that needs to be dispersed, not dissolved. Ensure thorough blending (as per the product description's recommended times) in the final step to prevent settling.

Ingredient Concentrations

• Methylsilanol Mannuronate: The recommended usage rate for firming is 4-6%. Your proposed 3% is below this range and may not provide the desired tightening effect. Increasing the concentration would require adjusting the water percentage.
• Aquamax (Sepimax Zen): If "Aquamax" refers to Sepimax Zen, the recommended usage rate is 0.5-2%. Your proposed 3% is above the maximum recommended rate, which could affect the texture and stability. Consider reducing the concentration to within the recommended range.

Recommendations

1. Review Sym-White Compatibility: Given the strong warning about amino acids and proteins, you may need to reconsider using Sym-White alongside Wrinkle-Fill and Glycosaminoglycans Complex. You might choose alternative whitening agents or adjust the formulation significantly.
2. Adjust Mixing Temperatures: Increase the hot process temperature for Parts A and B to 70-75°C for proper emulsification with Sensitive Cream Maker.
3. Add Heat-Sensitive Ingredients in Cool-Down Phase: Ensure Parts C and D ingredients (including Pure-Baicalin, Palmaria Palmata Extract, Glycosaminoglycans Complex, HydroAlgae, Encapsulated Salicylic Acid, Sym-White, Aquamax, and Preservative) are added only after the main emulsion has cooled below 40°C.
4. Adjust Concentrations: Consider increasing Methylsilanol Mannuronate to 4-6% and decreasing Aquamax (Sepimax Zen) to 0.5-2%. Adjust the water phase accordingly to maintain 100% total.
5. Verify Preservative Compatibility and pH: Confirm that your chosen preservative is compatible with all ingredients and effective at the target pH range of 4-5. Carefully adjust the final pH of the formula after all ingredients are added.
6. Small Batch Testing: Always test the formulation in a small batch first to check for stability, texture, color changes, and overall compatibility before making a larger batch.

By addressing these points, you can improve the stability and effectiveness of your homemade face cream.