Questions about Anti-irritant, Aveenoat Solubility, and Water-Free Vitamin C Serum Formulation

Formula Check and Questions

1. Regarding the need for an anti-irritant in the first formula:

   • The staff stated that MSH White Absorb™ (ID 881) is not irritating to the skin, and the other ingredients listed (B3 ID 74, GlucoBright ID 116, cream maker - category 36) are also not irritating.
   • Therefore, they do not think it is necessary to add an anti-irritant (category 58) unless your skin is already prone to irritation from other products. (The staff emphasized that allergy and irritation are different).
   • The staff also recommended adding a preservative (category 34) to the formula, specifically Mild Preserved Eco (ID 1001) at 1%.

2. Regarding Aveenoat dissolution without heat:

   • The staff confirmed that Aveenoat (ID 1398) can dissolve without using heat, but it will require a longer blending time for complete dissolution.

3. Regarding percentages of Propylene Glycol and Ethoxydiglycol for a water-free Vitamin C serum:

   • The staff stated that standard Vitamin C (L-Ascorbic Acid, ID 133) can dissolve in Propylene Glycol (ID 138) or Ethoxydiglycol (ID 137) up to a level not exceeding 5% when used individually.
   • The staff's reply does not provide a specific ratio for using both Propylene Glycol and Ethoxydiglycol together in a water-free serum formulation, but indicates the solubility limit of Vitamin C in each solvent is around 5%. A water-free serum formulation using L-Ascorbic Acid typically involves dissolving the Vitamin C powder in a blend of non-aqueous solvents. The exact percentages of Propylene Glycol and Ethoxydiglycol when used together would depend on the desired Vitamin C concentration and the overall formulation strategy, keeping in mind the solubility constraint.