Curly/textured hair can be particularly sensitive to the effects of damage and dryness, and vitamin C rapidly neutralizes residual chlorine—removing an oxidant that can continue to damage the hair fiber.
The chemistry
Pool chlorine exists substantially as hypochlorous acid (HOCl) and hypochlorite, which are strong oxidizing agents. Research on swimmers' hair has found that hypochlorous acid can penetrate through the cuticle into the cortex, while reviews of hair science describe chlorine exposure as contributing to cuticle damage, keratin degradation and breakage.
Vitamin C, ascorbic acid or sodium ascorbate, which is particularly relevant to Vita C—chemically reacts with chlorine. The USDA describes the sodium-ascorbate reaction essentially as:
Sodium ascorbate + hypochlorous acid → dehydroascorbic acid + sodium chloride + water
The reaction is rapid, and sodium ascorbate neutralizes chlorine without the pH reduction associated with ascorbic acid.
EPA researchers have similarly demonstrated that ascorbic acid rapidly reduces residual oxidizing chlorine, including HOCl and hypochlorite.
Why that's especially interesting for curls
Here's where your newsletter story gets good.
Curly/textured hair isn't chemically a completely different material, it's still primarily keratin but its geometry and physical behavior make maintaining the cuticle, moisture balance and manageability especially important. There's substantial scientific literature specifically examining porosity, mechanical damage and cosmetic treatment of textured hair.
Chlorine exposure is associated with loss of protective hair lipids and damage to hair proteins. The American Academy of Dermatology specifically notes that chlorine can dissolve protective hair lipids and contribute to protein-bond damage, leading to dryness, brittleness and breakage.
So the Vita C mechanism is beautifully straightforward:
Chlorine is an oxidizer → oxidation can damage the hair fiber → Vitamin C neutralizes residual chlorine → removing the chlorine stops that residual chlorine from continuing to act as an oxidant.