Water-Based Serum Formulation: Compatibility, Usage, and Preservation

Question

I am developing a water-based serum formulation containing Yeast Resurface, Encapsulated Salicylic Acid (10%), Vitamin B5, and Ethoxydiglycol.

I have the following questions:

Are Yeast Resurface and Encapsulated Salicylic Acid compatible in a water-based formula?
Is Vitamin B5 sufficient as a moisturizer in this formula?
Is a preservative necessary, and if so, what type and percentage do you recommend?
Will the pH need to be adjusted before adding the preservative?
Can this formula be applied all over the face?
Is using Encapsulated Salicylic Acid at 10% appropriate or safe? What is the recommended usage?
Can this formula be used together with products containing Copper Peptide?
I plan to mix the ingredients by hand using the following steps:
- Mix water, Yeast Resurface, Vitamin B5, and Ethoxydiglycol.
- Add Encapsulated Salicylic Acid and mix.
- Add preservative and mix.
  
  Are these steps correct? How would the steps differ if using a blender?
Can GlucoBright be added to this formula? If so, what is the maximum recommended usage percentage?
Is Ethoxydiglycol a preservative, or does it have another function?

MySkinRecipes Expert · Accepted Answer

Based on the conversation with the staff: Compatibility: Yeast Resurface and Encapsulated Salicylic Acid can be mixed in a water-based formula. Formula Composition: The formula includes Vitamin B5 as a moisturizer, which the staff believes is sufficient. You can add more moisturizer if your skin feels dry. A preservative is necessary. The staff recommends Phenoxyethanol SA (Optiphen Plus, ID 928) at 1%. The pH of the formula will be in the range of 4-6 and does not require adjustment before adding the preservative. Usage: The formula can be applied all over the face, provided all ingredients are used within the manufacturer's recommended rates. Using higher concentrations is at your own risk and should be under medical supervision. Regarding Encapsulated Salicylic Acid (ID 229) at 10%: The staff noted that the maximum recommended usage is 6.6%. Using 10% can cause skin irritation. At 6.6%, it is recommended to wash off the product after 5-15 minutes to avoid excessive irritation, dryness, redness, or peeling. BHA (Encapsulated Salicylic Acid) should be used separately from Copper Peptide products. Mixing: The mixing steps you provided are correct for hand mixing. If using a blender, you can mix all ingredients together and blend for 5-10 minutes. Adding GlucoBright (ID 116): You can add GlucoBright. Please check the product detail page for GlucoBright on the website for the recommended maximum usage percentage. Ethoxydiglycol (ID 137): Ethoxydiglycol is a penetration enhancer, not a preservative. You still need to add a preservative like Phenoxyethanol SA (ID 928).