Everything You Need to Know About Hair Color

ALLURE PODCASTThe Science of Beauty: Everything You Need to Know About Hair ColorOn the latest episode of The Science of Beauty podcast, we’re taking a closer look at the fascinating chemistry of hair dye and why it matters to you and your hue. (Available on Apple Podcasts, Spotify, or wherever you listen to podcasts.) This episode made possible by Head & Shoulders, available at Target.

By Dianna Mazzone

December 23, 2021

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A hair colourist applying pink hair colour to a client's long blonde hair.Mint Images

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It's been said that seeing is believing, but when it comes to beauty products, sometimes you've just got to trust the science. Don't get us wrong: We know for a fact that retinol softens fine lines and that vitamin C helps fade dark spots; it's just that you won’t see those effects straight out of the gate. Hair dye, however, is not one of those products — it's science you can see, instant gratification at its finest.

But what's happening on a chemical level that allows hair dye to provide such speedy — and dramatic — results? We at Allure's The Science of Beauty podcast thought it was high time to investigate. With help from cosmetic chemist Anne Wagner, Ph.D., hosts Jenny Bailly, executive beauty director, and Dianna Mazzone, senior beauty editor (and yours truly), get to the bottom of it on our latest episode while also sorting out the differences between the seemingly endless array of at-home hair dyes on the market.

So whether you've been coloring your hair for decades or you're just now contemplating your first dye job, you're going to want to listen to the full episode. To get your gears going in the meantime, though, here are three of the most fascinating takeaways.

The act of dyeing one's hair is far from a modern concept. 

In fact, there's evidence that during the Paleolitic era (roughly 2.5 million years ago) humans may have used the iron oxide found in dirt to color their homes, textiles, and — you guessed it — hair.

Your natural hair color is a matter of melanin. 

Just like your skin, the hue of your hair is determined by melanin — more specifically, your unique combination of eumelanin and pheomelanin. When hair turns gray or white with age, it's because the cells that produce melanin, called melanocytes, have died, says Dr. Wagner.

The hair dye used at salons is generally no different than at-home formulas. 

But though the goop may be the same, "what differs between [them] is the artist," says Dr. Wagner. A trained professional can customize blends to create more nuanced colors, she adds.

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