L-ascorbic acid is pure vitamin C: a potent antioxidant that brightens tone, supports collagen synthesis, and helps defend against urban oxidative stress. It is also famously unstable — which is why packaging and pairing matter more than percentage.
It is the most researched topical antioxidant in dermatology. Ferulic acid and vitamin E stabilize it and extend its activity; Coyglow's C-Forward Serum uses exactly this CE-ferulic architecture at 15%.
How to use: Mornings under sunscreen — the antioxidant pair with SPF is synergistic. Store away from heat; a slight darkening is normal oxidation.
Cautions: High acid content can sting very reactive skin at first; introduce on alternate days.