What color should vitamin C serum be?
Depending on the formulation, Vitamin C is typically clear or light yellow in color. Vitamin C (L-Ascorbic Acid) is typically unstable in water and oxidizes over time.
How do I know if my vitamin C serum is still good?
Many serums are yellow, but if your product takes on a brown or dark orange hue, it's time to toss because it's gone bad. If your serum starts out clear and turns yellow, that's also a sign it's oxidizing and will be less effective.
What consistency should vitamin C serum be?
A vitamin C serum is a skin-care product packed with vitamin C. It has the consistency of a liquid or gel, and is applied topically to the skin.
How do I know if my vitamin C serum is oxidized?
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.