Water Essence Formulation: Storage, Shelf Life, and Preservation

Question

Hello,

I am planning to mix a water essence for normal to dry skin based on a formula previously provided by staff:

Galactomyces Ferment Filtrate (Pitera) - Remaining portion to reach 100%
Double Hyaluron Liquid - 5% (Replacing Hyaluronic Acid Standard/Nano which is powder form and harder to use)
Vitamin B3, Niacinamide (Safe-B3™) - 5%
Phenoxyethanol SA - 0.2% (Reduced from 1% because Pitera used in large quantity already contains preservative from the manufacturer)
Vitamin B5 - 1%
Ethoxydiglycol - 5% (Helps skin absorb ingredients better)
Flora Solve Clear - 1% (Helps the formula adhere better to the skin)

I would like to know:

Should the mixture be stored in the refrigerator?
How is the shelf life of this water essence determined (which ingredient's expiry date)?
Can ingredient #4 (Phenoxyethanol SA) be omitted?

MySkinRecipes Expert · Accepted Answer

Hello,

Regarding your questions about the water essence formulation:

Storage: Yes, it is highly recommended to store the finished product in the refrigerator. This helps maintain the stability and freshness of the ingredients, especially Galactomyces Ferment Filtrate, and can extend the product's shelf life by inhibiting microbial growth.
Shelf life: The shelf life of a homemade cosmetic product is generally determined by the ingredient that expires first, assuming proper preservation and hygiene during preparation. However, even with preservatives, homemade products typically have a shorter shelf life than commercially manufactured ones due to potential contamination and lack of rigorous stability testing. A common guideline is to use the product within 3-6 months after mixing, regardless of the individual ingredient expiry dates. Always observe the product for changes in color, odor, or texture, and discard if any changes occur.
Omitting Phenoxyethanol SA (Preservative): It is strongly advised not to omit the preservative (Phenoxyethanol SA / Optiphen Plus). While Galactomyces Ferment Filtrate may contain a preservative from the manufacturer, it is usually not sufficient to preserve the entire final formulation, especially when other ingredients are added and the product is exposed to air and potential contaminants during use. Omitting the preservative will make the product highly susceptible to bacterial, mold, and yeast growth, rendering it unsafe and causing it to spoil very quickly (potentially within days or a week). The reduced percentage (0.2%) is likely the minimum recommended level for this formulation. Preservatives are essential for water-based products to ensure safety and stability.

Hope this helps!