If the vitamin C serum is yellow, it was most likely manufactured over 6 months ago with proper storage. A serum that is dark brown in color indicates the vitamin C serum has oxidized and will not be as effective and should be discarded. 28 февр. 2022 г.
How do you know if vitamin C serum is oxidised?
The easiest way to see if your vitamin C serum has become oxidised is by making note of the colour. Serum containing more vitamin C are clear which begins to change to a yellow or brown colour roughly 3 months after opening.
Does vitamin C serum get oxidized?
After contact with light, heat and air, vitamin C eventually oxidizes and loses its potency. You'll know it when your serum changes colour, turning brown.
How long does it take for vitamin C serum to oxidize?
Once your serum turns yellow, red, or brown, it has become oxidized and will no longer be effective. For most formulas, this usually happens after about 3 months at room temperature or 5 months with refrigeration, although the exact amount of time will vary between brands.
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