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?
Freezing is never recommended for a cream or lotion because it can cause the motion to break. A good cosmetic formulator does some worse case freeze thaw testing to make sure their products won’t fall apart after one or two cycles but you shouldn’t be deliberately exposing your product to freezing temperatures to prevent oxidation.
If it’s a true serum it’s less likely to separate than an emulsion but, in general, freezing is not a good idea even for solutions because it messes with the solubility of the components.