The reference-standard antioxidant serum — 15% L-ascorbic acid, 1% vitamin E, 0.5% ferulic acid at pH ≤3.5 (the original Duke patent). Demonstrably increases photoprotection when layered under SPF. Expensive, but what every other 'CEF dupe' is trying to be.
What this is good for
✓ Great forDark SpotsAgingDullnessprotect
• Use with caution ifSensitive skinDamaged barrier
Ingredient stack
Each ingredient is listed in descending concentration. Above the 1% line the order is regulated — below it, brands can list in any order.
Ingredients above the dashed gold line are dosed above 1% (the regulatory threshold) — these are what the formulation is really built on.
position-estimated %★ brand-disclosed %1% regulatory line
What's actually doing the work
Vitamin C
L-Ascorbic Acid / Ascorbyl Glucoside / MAP / THDA
Vitamin
The gold-standard antioxidant for skin. L-Ascorbic Acid neutralises free radicals, inhibits tyrosinase to fade hyperpigmentation, is essential for collagen biosynthesis, and provides measurable photoprotection under SPF. Derivatives like Ascorbyl Glucoside and Tetrahexyldecyl Ascorbate are more stable and gentler. Results visible in 4–12 weeks.
Vitamin E
Tocopherol / Alpha-Tocopherol
Vitamin
The primary fat-soluble antioxidant in skin. Protects cell membranes from lipid peroxidation, dramatically enhances and regenerates Vitamin C, and provides emollient and barrier-supporting benefits. Combined with Vitamin C, the photoprotective synergy is greater than either alone.
Ferulic Acid
Hydroxycinnamic Acid / Antioxidant Booster
Antioxidant
A plant-derived antioxidant found in cell walls of grains and seeds. Most important function: it doubles the photoprotection of Vitamins C+E and extends the shelf stability of unstable L-Ascorbic Acid formulas. The classic CE Ferulic formula (15% C, 1% E, 0.5% ferulic) pioneered this combination and remains the gold standard.
Routine placement
Morning only
Similar on the shelf
Put this in context
Skin Stacker is independent and receives no payment from any brand. Ingredient analysis is based on publicly disclosed INCI lists and the peer-reviewed literature. Formulations change — always re-check the label on your specific batch before using.