You walk out of the living room with a deep, cool brown. Two weeks later, in the light of day, your lengths appear coppery, almost red. Even without coloring, many brunettes see their ends turn red in the summer. It seems that the color “turns” on its own.
Understanding why brown hair systematically turns red requires looking at the fiber closely: natural pigments, oxidation, sun, water, styling products. The colors, especially dark, further modify this cocktail. And each hair reacts in its own way, depending on its thickness, porosity and possible white hair.
Brown hair, melanin and red highlights
Two key pigments coexist in the same hair: eumelanin, brown to black, and pheomelanin, yellow to red. Brunettes have a lot of eumelanin. Under the effect of UV rays, heat and frequent washing, this eumelanin is damaged first, leaving the pheomelanin more visible to the naked eye.
On brown or chestnut hair, the natural base is already warm, tending towards red or orange. As soon as the fiber lightens, after summer, old discoloration or repeated straightening, this background comes out. The exposed lengths then appear to brown, even without coloring.
Coloring, oxidation and reddening brown hair
When we color a brown, we add artificial pigments which do not all stay in place. Jenna Mast explains it very clearly: , she points out to Harper’s Bazaar magazine. The blue molecules first leave the fiber, leaving the yellow and red pigments, therefore the red highlights, to appear.
The stronger the coloring peroxide, the more we open the cuticle and the more internal heat comes out. , warns Jenna Mast. Hard water, metals, aggressive shampoos and already sensitized hair further accelerate this disgorgement.
How to limit red highlights on brown hair
The good news is that we can significantly slow down this turn to red with a few targeted reflexes and appropriate care.
- Alternate a mild shampoo with a blue or green shampoo once every 7 to 15 days, depending on the intensity of the reflections.
- Protect your lengths from the sun, the sea and the pool with a UV spray and careful rinsing.
- Ask your hairdresser for a patina or an ash brown gloss to redeposit cold pigments between two colorings.
At home, a shower filter can limit the impact of limescale and metals, while avoiding excessively hot water and unprotected heating appliances. If the color changes very quickly, becomes reddish throughout the hair and is accompanied by fatigue or unusual loss, medical advice is preferable to a new color mixture.
Why does my brown hair turn red after every summer?
Sun, salt and chlorine lighten the fiber and reveal the warm bottom.
Is purple shampoo enough to remove red highlights?
Violet especially neutralizes yellow; for reddish browns, it is better to use blue or green pigments.
How often should I use blue or green shampoo?
Once every 7 to 15 days is enough for maintenance, alternating with a mild shampoo.
