Protecting Hair From Chlorine and Salt Water — Effective Methods Backed by Chemistry

Chlorine and sea salt — how exactly do they damage hair?

Summer is the season of the pool and the sea, but it's also the season of damaged hair. Before we cover protection methods, it's worth understanding the mechanism of the damage — because only then do the defensive strategies start to make sense.

Chlorine (or more precisely hypochlorous acid, HOCl) used in pools is a powerful oxidiser. It attacks the disulphide bonds in keratin — the very bonds that give hair its strength and elasticity. Oxidised disulphide bonds cannot be rebuilt by natural processes, which leads to a permanent weakening of the hair's structure. On top of that, chlorine strips the natural lipids from the cuticle, exposing the hair cortex to further damage.

Sea salt water works differently, but is just as destructive. Salt (NaCl) is a hygroscopic crystal — it draws water from inside the hair to the outside, causing dehydration. At the same time, salt crystals deposited on the hair's surface act like tiny lenses, focusing UV radiation and amplifying the photodegradation of keratin.

Pre-swim saturation — the simplest and most effective method

The principle of pre-swim saturation is based on simple physics: hair acts like a sponge with a limited absorption capacity. Dry hair can soak up to 30% of its own weight in water. If that "capacity" is filled with clean tap water, the hair physically has no more room for chlorinated or salty water.

The technique is effortless: before getting into the pool or sea, thoroughly soak your hair with clean water in the shower. Make sure your hair is genuinely saturated — a light dampening isn't enough. Your hair should be dripping wet. This one simple step reduces the absorption of chlorine and salt by more than 50%.

For even better protection, combine pre-swim saturation with one of the chemical-barrier methods below.

Coconut oil — a natural hydrophobic barrier

Coconut oil (Cocos Nucifera Oil) has unique properties that make it an ideal pre-swim product. Unlike most plant oils, coconut oil penetrates into the hair thanks to the small molecular size of lauric acid. It forms both an external barrier (on the cuticle surface) and an internal one (within the hair cortex).

Before swimming, apply a small amount of coconut oil to damp (not wet) hair, focusing on the lengths and ends. The oil creates a hydrophobic layer that physically hinders the penetration of chlorinated water. It doesn't eliminate contact entirely — it's not a shield — but it significantly limits it.

Alternative oils that work well as a pre-swim barrier:

• Argan oil — lighter than coconut, better for fine hair
• Avocado oil — rich in fatty acids, deeply penetrating
• Sunflower seed oil — high in linoleic acid, strengthens the lipid barrier

You'll find detailed profiles of these oils in our INCI ingredient database.

Vitamin C — neutralising chlorine at the chemical level

Ascorbic acid (Ascorbic Acid, vitamin C) is one of the most effective over-the-counter chlorine neutralisers available. The reaction is simple: ascorbic acid reduces chlorine (hypochlorous acid) to harmless chloride, while itself oxidising to dehydroascorbic acid.

Chemical reaction: C₆H₈O₆ + HOCl → C₆H₆O₆ + HCl + H₂O

Practical use: dissolve 1 teaspoon (about 5 g) of ascorbic acid in 250 ml of water in a spray bottle. After getting out of the pool, spritz your hair with the solution, massage it in for a minute and rinse with clean water. Vitamin C neutralises residual chlorine before it can oxidise the keratin any further.

Ready-made post-swim sprays are also available, containing Sodium Ascorbyl Phosphate (a stable form of vitamin C) combined with moisturising humectants. Look for them in our product search.

An important note: vitamin C works after exposure to chlorine, not before. It's not a barrier — it's an antidote. You'll get the best results by combining pre-swim saturation and coconut oil (before) with vitamin C (after).

UV protection — leave-in products with sunscreen filters

UV radiation degrades the keratin and melanin in hair — leading to colour fading, dryness and brittleness. In the context of the pool and sea, UV is an additional aggressor that compounds the damage from chlorine and salt.

Leave-in conditioners with UV filters are an important part of summer protection. On the INCI list, look for:

• Ethylhexyl Methoxycinnamate — a UVB filter, protects against the main damaging spectrum
• Benzophenone-4 — a water-soluble filter, effective in leave-in formulas
• Butyl Methoxydibenzoylmethane — a UVA filter (Avobenzone)

Apply a UV leave-in to damp hair before heading out into the sun. Remember to reapply after every swim — water washes off most filters.

Post-swim — chelating shampoo with EDTA

Even the best prevention can't replace proper cleansing after swimming. An ordinary shampoo can't cope with metal ions (copper from pool pipes, calcium and magnesium from hard water, salt from the sea), which settle on the hair and cause dullness, stiffness and greenish discolouration (copper on blonde hair).

A chelating shampoo contains substances that bind metal ions and remove them from the hair's surface. The key ingredient is EDTA (Disodium EDTA or Tetrasodium EDTA) — a chelator that forms soluble complexes with Ca²⁺, Mg²⁺, Cu²⁺ and Fe³⁺ ions, allowing them to be rinsed away.

Other chelators found in shampoos:

• Phytic Acid — a natural chelator from cereal grains
• Sodium Gluconate — a mild chelator, gentle on a sensitive scalp
• Citric Acid — a weaker chelator, but widely available

Don't use a chelating shampoo every day — it's an intensive cleansing product. Once a week during pool season, or after each day in the sea, is the optimal frequency. After a chelating shampoo, always use a moisturising conditioner, because chelators also remove the natural lipids from the cuticle.

Browse chelating shampoos in our product catalogue.

A complete protection strategy — before, during and after

The most effective protection is a combination of three stages:

1. Before swimming — saturate your hair with clean water (pre-swim saturation), apply coconut oil to the lengths and ends, and use a leave-in with UV filters
2. During — wear a swim cap (the only method offering 100% protection from chlorine), if possible
3. After swimming — rinse your hair with clean water immediately, apply a vitamin C spray, wash with a chelating shampoo, and apply a deeply moisturising mask

This strategy protects hair from chlorine as well as salt water, UV and metal ions. Each element reinforces the others — it's a system, not a single solution.