Formula Evaluation and Recommendations

Adding Perfect-C™ to the Formula

You can add Perfect-C™ (Ascorbyl Tetraisopalmitate) to a formula. Perfect-C™ is an oil-soluble form of Vitamin C that helps with skin brightening, reducing dark spots, and stimulating collagen production, which aligns with your sister's goals for addressing uneven skin tone and dark spots, as well as wrinkles.

Important Caution: Based on the information for Perfect-C™, it is stated that it should not be used with Zinc PCA in the same formula due to potential incompatibility issues that could reduce efficacy or stability.

Therefore, if you wish to add Perfect-C™ to the formula, you must remove Zinc PCA from the original formula.

Can the Original Formula (Including Perfect-C™) Be Used?

The original formula you provided cannot be used immediately if Perfect-C™ is added without modifications because it contains Zinc PCA, which is incompatible with Perfect-C™ as mentioned.

Furthermore, evaluating the original formula reveals additional points:

• DMAE 20%: A concentration of 20% is very high. The recommended usage is 1-10% (3% recommended), and using above 5% may cause skin irritation. This might not be suitable for your sister's skin, which experiences dryness and potentially thinness in areas like the cheeks near the nose. Reducing the concentration to around 3-5% would be safer and sufficiently effective.
• Zinc PCA 1%: While Zinc PCA helps control oiliness and stimulates collagen, given your sister's skin type which is somewhat dry in certain areas and the focus on wrinkles, dark spots, and uneven tone, Zinc PCA might not be the most essential ingredient. Crucially, it is incompatible with Perfect-C™.
• Insufficient Moisturizing Ingredients: As the staff previously advised, the original formula lacks sufficient highly effective moisturizing ingredients for dry skin. Rice Vitamin helps with moisture, but for skin experiencing dryness and flaking, other moisturizing agents should be added.

Recommendations for Maximum Efficacy and Formula Completeness

To achieve maximum efficacy in addressing wrinkles, uneven skin tone, dark spots, and also caring for your sister's dry skin, consider adjusting the formula as follows:

1. Remove Zinc PCA: This is necessary to effectively incorporate Perfect-C™ and avoid incompatibility issues.
2. Reduce DMAE Concentration: Lower it to 3-5% to reduce the risk of irritation while maintaining its effectiveness for lifting and reducing wrinkles.
3. Add Perfect-C™: Include Perfect-C™ at a recommended concentration (e.g., 5%) to help with skin brightening, reducing dark spots, and providing antioxidant benefits.
4. Add Moisturizing Agents: You should add highly effective moisturizing ingredients such as Hyaluronic Acid (using multiple molecular weights can help hydrate different skin layers, e.g., Hyaluronic Acid Standard Molecule, Hyaluronic Acid Small Molecule, or Hyaluronic Acid Large Molecule, or use 4D Hyaluronic Acid which combines multiple sizes) at a concentration suitable for dry skin (around 0.1-0.3% for powder forms or 2-10% for 4D Hyaluronic Acid). This will address the dryness issue and strengthen the skin barrier.
5. Adjust Product Texture: Since Perfect-C™ is oil-soluble and your sister's skin is dry, formulating a cream or lotion with an oil phase and emulsifier would help incorporate Perfect-C™ effectively and provide better moisturization and skin barrier support than a gel. If you prefer a gel texture, you might need to use a suitable solubilizer to incorporate Perfect-C™ into the water base, but this requires careful testing for stability and efficacy.
6. Check Formula pH: Perfect-C™ works best at pH 5.0-5.5. The final pH of the formula should be adjusted to this optimal range to ensure Perfect-C™ and other ingredients function effectively and the formula remains stable.

In summary: The original formula contains good ingredients for wrinkles but has an incompatibility issue between Perfect-C™ and Zinc PCA and lacks sufficient moisturizing ingredients for dry skin. Adjusting the formula by removing Zinc PCA, adding Perfect-C™ and moisturizing agents like Hyaluronic Acid, reducing the DMAE concentration, and considering an appropriate product texture will result in a more complete and effective formula for your sister's skin concerns.

Regarding your question about separating into 3 formulas and layering: As advised by another staff member, combining compatible ingredients into a single formula by adjusting concentrations is often more convenient and equally effective as layering multiple single-ingredient formulas. Using a single, well-formulated product with compatible ingredients reduces steps and potential irritation from layering multiple products.