Oconor asks…A lot of people, myself included, are taking a DIY route for this product, and I know refrigeration will slow the oxidation, but how will freezing affect a formulation like Skinceuticals C and E Ferulic and the LotionCrafter copycat kit?
The Beauty Brains respond:
Freezing is never recommended for a cream or lotion because it can cause the emulsion to break. A good cosmetic formulator does some worse case freeze-thaw testing to make sure their products won’t fall apart if the temperature dips into the freezing range but you shouldn’t be deliberately exposing your product to freezing temperatures just to prevent oxidation.
If the product is a serum then its more of a solution of ingredients than an emulsion so it’s less likely to separate. However, freezing is still not a good idea because it messes with the solubility of the components.
Prolonging the shelf life of a product by storing it in the fridge is perfectly fine. The kinds of chemical reactions that cause product to go bad double in speed for every 10C increase in temperature. So, cooler is better.