The science behind that gray hair dye fad

celebs gray hair

From Ciara's recent turn in silver at the Met Gala ball, to models strutting the catwalk, gray hair is popping up everywhere -- and it's not just a testament to an aging demographic. In fact, gray hair is increasingly framing the faces of people barely out of college with nary a gray straggler.

It began as a statement of sorts, an ironic declaration of the ennui of Millennials. "We might be 20-somethings," it seems to declare, "but we've dealt with a recession, job searches, relationship seesaws, social media shamings, political bickering and wars. We're wiser than our age."

"Millennials like the idea of a fashionable statement," said Aura Friedman, a colorist at Sally Hershberger salons in New York City. She pointed to gray's unique duality as being at once neutral and head-turning, particularly when paired with a wrinkle-free face.

Millennials are also often looking for standout shades of gray, which means colorists like Friedman are tasked with swirling cotton candy pinks and lilac violets into a base shade of gray.

For those not familiar with gray hair dye, it's far from the simple paint job you might think. It all begins with a bleaching -- regardless of natural color -- to a pale yellow (think Daenerys, for Game of Thrones fans).

"It's the most intense thing you could ever do to your hair," Friedman said. "The quality of the hair changes drastically. The texture changes almost immediately."

Part of the reason why bleaching is so harsh on the scalp? Ammonia. This combines with peroxide to move hair away from its natural state and acts as a "cuticle opener" so that hair is better able to take the dye.

To understand this, a quick chemistry lesson is necessary: Ammonia is alkaline in nature, which means it sucks up moisture. Remember those PH strips from science class, where one end was acidic and the other basic, with the middle perfectly balanced? In the gray hair dyeing process, ammonia pushes hair PH toward the very basic end.

And as anyone with naturally gray hair can attest to, it's not exactly the texture of a soft bed of feathers. So gray haired folks -- whether it's natural or dyed -- are dealing with dry locks that are (unironically) extremely basic.

Mariacristina Castan is a Frankfurt, Germany-based biochemist and scientific communications manager at Wella, which manufactures hair dyes with Procter and Gamble. Castan said the challenge in creating gray hair dyes is finding the sweet spot of being gentle enough to not burn off your scalp but strong enough to absorb gray.

Castan said it's nearly impossible to change the harsh bleaching process, so her team at Wella is trying to make the graying process gentler -- and keep your hair from turning into straw.

Reinventing the color black

The technology behind dyeing hair has been stagnant for decades, but Castan's team is changing that. Recent beauty products have heavily marketed "natural" ingredients, but Castan points out that the flower pollen, nuts, and henna can often cause allergic reactions.

So Castan's team has developed a non-toxic chemical: 20Methoxymethyl-p-Phenylenediamine, otherwise referred to as ME+, which tricks the immune system into not thinking hair dye is an allergen and attacking it. This means that gray hair dye -- the harshest possible color a person can maintain -- is more accessible, less harsh, and possibly safer to handle, all thanks to a laboratory-induced molecular change.

Friedman emphasizes that no matter the advances in technology, it's always going to be a long effort at the salon.

"If you want to go gray, definitely consult an expert," she said. "The application itself takes two hours" -- and that's with "virgin," uncolored hair. If your hair history includes any dye, clock in a few more hours.

But that's just a few hours compared to the decades it normally takes a person to go completely gray, au naturale.

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