Formula Feedback and Mixing Advice

Your proposed formula for a skin brightening and moisturizing cream is a good starting point, incorporating key ingredients like L-ascorbic acid, Vitamin E (d-alpha tocopherol), and Ferulic Acid, known for their antioxidant and brightening properties. Glycerin is included for moisture, Propylene Glycol as a solvent, and Laureth-23 as an emulsifier.

Formulation Adjustments

The feedback correctly points out a critical aspect: Ferulic Acid is not soluble in Propylene Glycol or water. It requires a suitable solvent like Ethoxydiglycol or ethanol to properly dissolve and integrate into the formula. Therefore, you would need to include Ethoxydiglycol in your formula to ensure the Ferulic Acid is fully dissolved and effective.

Additionally, the suggestion to include Hyaluronic Acid and Vitamin B5 (Panthenol) is excellent for boosting the moisturizing properties of the cream, aligning with your goal of a brightening and moisturizing product. Hyaluronic Acid is a powerful humectant that draws moisture into the skin, although, as noted, it can sometimes contribute to a slightly sticky feel depending on the type and concentration used. Vitamin B5 also acts as a humectant and helps improve skin barrier function and soothe the skin.

Mixing Equipment

Regarding mixing equipment, for smaller batches, such as 100 grams, simply using a clean spoon or spatula to mix in a clean glass container is sufficient. The key is ensuring thorough mixing and maintaining cleanliness to avoid contamination.

For larger quantities, like a kilogram, a standard kitchen mixer designed for dough or eggs can indeed be used. Again, ensuring the equipment is thoroughly cleaned and sanitized before use is paramount for the stability and safety of your cosmetic product.

In summary, while your base formula is promising, incorporating Ethoxydiglycol for Ferulic Acid dissolution and considering the addition of Hyaluronic Acid and Vitamin B5 will enhance its effectiveness and moisturizing benefits. Simple, clean mixing tools are adequate depending on the batch size.