Serum formulation adjustment with Silky Serum Base, actives, water, and preservative

Question

I'm formulating a serum for oily T-zone and under-eye wrinkles using the following ingredients:

Acetyl Hexapeptide-8 (Argireline) 7%
Wakame Extract (Brown Sea Weed) 3%
Pep®-Coll (Palmitoyl Tripeptide-5) 3%
Panthenol (Vitamin B5) ExtraLite™ 2%
Silky Serum Base (Face/Eye) 50%
Distilled Water 34%
Preservative (Mild Preserved Eco™) 1%

I was advised to reduce the percentage of Silky Serum Base to 15-20% and add distilled water to make up the difference, as well as add a preservative like Mild Preserved Eco™ at 1%.

Is it necessary to add water and a preservative to this formulation?
What are the correct mixing instructions when using Silky Serum Base, especially when adjusting the percentages as advised?

MySkinRecipes Expert · Accepted Answer

Recommended Serum Formulation for Oily T-Zone and Under-Eye Wrinkles

Based on your skin concerns (oily T-zone, under-eye wrinkles) and age (26), here is advice on your proposed serum formulation:

Using Acetyl Hexapeptide-8 Alone: Acetyl Hexapeptide-8 (Argireline) cannot be used at 100% concentration directly on the skin. It must be incorporated into a base product. However, it can be used as the primary active ingredient in a formulation at a concentration typically not exceeding 10%.
Your Proposed Formulation and Recommended Adjustments: Your chosen ingredients (Acetyl Hexapeptide-8, Wakame Extract, Pep®-Coll, Panthenol) are suitable for targeting wrinkles and hydrating the under-eye area. Silky Serum Base is also appropriate for a lightweight serum.

Based on expert advice, the percentage of Silky Serum Base should be adjusted, and both water and a preservative are necessary for a stable and safe product. Here is a recommended adjusted formula (total 100%):
- Acetyl Hexapeptide-8: 7%
- Wakame Extract (Brown Sea Weed): 3%
- Pep®-Coll (Palmitoyl Tripeptide-5): 3%
- Panthenol (Vitamin B5) ExtraLite™: 2%
- Silky Serum Base (Face/Eye): 15-20%
- Mild Preserved Eco™ (Preservative): 1%
- Distilled Water: Adjust the percentage to reach 100% (e.g., 69% if using 15% base, 64% if using 20% base).
Adding Water: Yes, distilled water is essential. It acts as a solvent for water-soluble ingredients and helps achieve the correct serum consistency.
Adding a Preservative: Yes, a preservative is crucial for any water-based product to prevent microbial growth and ensure safety. Mild Preserved Eco™ (Ethylhexylglycerin, Caprylyl Glycol) is recommended as a safe and effective option without carcinogenic properties. Use it at 1%.
Mixing Instructions (for Silky Serum Base): Please note that Silky Serum Base requires a blender. Mix all ingredients except the base and preservative into the water first. Then, while blending the Silky Serum Base, slowly add the water mixture until fully combined. Add the preservative last and mix well.
Expected Shelf Life: With a proper preservative, the serum should have a shelf life of approximately 12 months when stored correctly.