How to prevent green hair from the pool

Wet your hair with clean water first, coat it with a barrier product, put a cap on, and rinse with fresh water the second you get out. The reason is copper, not chlorine. Copper from pipes, heaters or copper-based algaecides binds to porous hair, and that bound metal is the green you see.

Why hair turns green in the pool

A blonde kid climbs out of the pool on an afternoon in late June, swim cap in one hand. Her mother put that cap on before the first lap, because everybody says chlorine wrecks blonde hair. The ends of her hair have a green cast.

The green is copper. Pool water can carry it from copper pipes, heaters and copper-based algaecides. Chlorine oxidizes the copper, and the oxidized metal binds to hair, most visibly on light or porous hair. Bleached, highlighted, chemically treated, fine or already-damaged hair is more porous, which is why blondes and color-treated swimmers show it first.

Chlorine does its own damage to hair. It strips the natural oils that coat each strand and roughens the cuticle, so hair goes dry and tangly and color fades faster. That is a texture problem. Green is a metal problem.

Pool chemistry varies, so some pools green hair and others never do.

The five steps

1. Soak your hair with clean water first. Use the pool shower or a water bottle. Hair takes up water like a sponge, so hair that is already full of clean water takes up less pool water. That reduces how much copper-bearing water gets in. It does not block it.
2. Coat it. On damp hair, work in a barrier product and pay special attention to the ends. AQUA GUARD Pre-Swim Hair Defense is made for this step. The directions on the listing say to apply a generous amount, give it 3 to 5 minutes to absorb completely, then swim. It is $24.99 for 5.3 oz on Amazon, where it has 4.4 stars across 3,364 ratings, and the listing says it "prevents green hair; protects natural color". Kids' hair is often finer and more porous than adult hair, so it takes up more; AQUA GUARD also makes Pre-Swim Hair Defense For Kids ($21.99 for 8.45 oz), which its listing calls a "Chlorine Hair Shield + Easy Comb-Through".
3. Put a swim cap on over the coated hair. Go back to the kid on the deck. Her mother had planned for chlorine. The green was copper all along, which is why the cap alone did not stop it: a cap keeps most water off the hair but not all of it, and water gets in at the edges, copper included. Over coated hair the cap is a second layer. Over bare hair it is the only one.
4. Rinse the moment you get out. Use fresh water at the pool shower before you head home. Rinsing right after swimming removes a lot of what is sitting on the surface, and the listing's directions say the same: "Rinse after swimming with clear water."
5. Shampoo, then condition. A shampoo made for swimmers is formulated to lift chlorine and metal residue. Conditioning afterwards puts moisture back. AQUA GUARD Chlorine Clarifying Shampoo is $17.99 for 9.5 oz and is listed to "remove chlorine & pool hair smell".

If your hair is already green

Green hair is oxidized copper sitting on the hair, so the job is lifting metal. A clarifying or chelating shampoo is made to lift mineral and metal buildup, and that is the tool for the job.

Purple shampoo is a different tool. Toning purple cancels yellow, and green is not yellow, so it will not shift the tint.

AQUA GUARD's line is built around preventing the green rather than removing it. The Chlorine Clarifying Shampoo is listed to "remove chlorine & pool hair smell", and its listing does not mention copper. Any fix is temporary if the next swim is unprotected, because the water still carries the copper. Run the five steps before you get back in.

Questions people ask

Does chlorine turn hair green?

Not by itself. Copper and other metals in the water are the source of the tint, and chlorine oxidizes the copper so it binds to hair. Chlorine's own effect on hair is dryness: it strips the natural oils and roughens the cuticle.

Why does only blonde hair turn green?

Light hair shows the metal most visibly. Bleached, highlighted, chemically treated, fine or already-damaged hair is more porous, so it takes up more pool water and shows the tint first.

Does a swim cap prevent green hair?

It helps and it is not a seal. A cap keeps most water off the hair but not all of it, and water gets in at the edges. Coat the hair first and put the cap over it.

Does ketchup fix green hair?

Ketchup is a home remedy people pass around for green hair. This page cannot tell you whether it works. The route it can stand behind is a shampoo formulated to lift metal residue, then the five steps.

How long does green hair last?

Until it is lifted. It depends on how much metal has bound to the hair and how porous the hair is, so there is no number we can give you. A chelating shampoo shortens it. An unprotected swim resets it.