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As I type these words, my nails are 10 small silver mirrors, reflecting the overhead fluorescent lights as I move my fingers across my keyboard. I learned about these so-called chrome nails from The Atlantic’s fashionable deputy web editor Swati Sharma, and shortly thereafter, she and I went and got manicures so I could see the process in action. The mirror effect was created with a special powder that a nail technician, as they’re referred to in the industry, rubbed onto a layer of polish with a tiny sponge. It was mesmerizing, and a little mystifying. How did the glitter powder transform into a solid, shiny surface?

We have the red-carpet mani cam to thank, at least partially, for the surge in popularity of nail art, says Beth Livesay, the executive editor of Nails magazine. When celebrities started treating their nails as canvases for miniature art, the trend caught on with the public, too. But lately, the nail-art galleries of Pinterest and Instagram have been displaying not just polish hand-paintings, but futuristic-looking effects like chromes, cat’s eyes, and holographic rainbow nails.

“Right now, the trends are the effects,” Livesay says. “The bar’s been raised universally for nail art.”

I spoke with a couple cosmetic chemists to understand the science behind turning normal human nails into mirrors, or gemstones, or shimmering fish scales. They explained the basic chemical processes behind polishes and effects. (I can’t, however, confirm the exact ingredients of many specific brands’ products. I reached out to OPI, Orly, Creative Nail Design, and Whats Up Nails—all of which declined to be interviewed or did not return requests for comment.)

It starts with understanding how regular nail polish works, and how the longer-lasting “gel” manicures are different. Regular polish, or “lacquer” as some in the industry call it, is made of polymers—long chain molecules that are good at forming strong structures—dissolved in solvents. Once the polish is painted on, the solvents evaporate, leaving behind the film formed by the polymers (and the pigment that gives it color). Lacquers also often include other resins and plasticizers to help the polish adhere to the nail, and to make it more flexible. To remove it, you apply a solvent in the form of nail-polish remover (typically containing acetone or ethyl acetate), and the lacquer dissolves.

“It’s very much like hair spray,” says Doug Schoon, the president of Schoon Scientific and a former chief scientist at a commercial nail-polish company. “You spray it on your hair, the solvent evaporates off, and it leaves a coating that holds the hair in place. Nail polish is a little more sophisticated than hair spray, because hair spray just has to do one thing, and really doesn’t last that long, whereas nail polish has to be shiny, adhere to the nail plate, be resistant to scratching and dings, hold the color and not fade, and come off easily when you want it.”

Gels—which Livesay says also helped fuel the start of the nail-art craze—are longer-lasting substances that are mostly available in salons, and which harden under UV or LED light. Whereas the film-forming polymers are already mixed into your standard nail lacquer, “in the case of artificial nail coatings, they’re actually making the polymer on the nail,” Schoon says. “The gels are oligomers and monomers, which are snippets of polymers, and then when the UV light hits [the gel], it causes these snippets to all join together and assemble like a jigsaw puzzle.”

What happens under the lamp is a free-radical reaction, “which sounds really rebellious,” says Jim McConnell, a chemist and the cofounder of Light Elegance, a nail-product company. The light causes a compound in the gel to release a very reactive molecule known as a free radical, which then attacks and opens up bonds within the monomers and oligomers. Those bonds are then free to re-form with adjacent molecules into a more intricate chain, creating the hard polymer that makes the gel manicure so durable and long-lasting.

Confusingly, though, a lot of different products are called “gels.” “It’s a struggle constantly to get the right terminology in place,” Livesay says. “A lot of times people don’t know what they’re asking for.”

There are hard gels, which are the most durable, and can only be removed by filing them off. These are more popular in Europe, according to McConnell. Soft gels are similar, but slightly less durable and easier to remove. Then there are gel polishes, which are more likely to be what the average American will encounter if they just walk into a salon and ask for a “gel manicure.” The composition of these can vary depending on the brand—some are soft gels mixed with solvent; some are gels mixed with lacquer. Both can be removed with acetone.

(A word of caution from Schoon: With any sort of gel, a technician should never file it off all the way down to your natural nail. “This is like putting a bunch of glue on your roof and then taking a crow bar and scraping the glue off. You're going to pull shingles up, too.”)

Gel manicures form the base for a lot of the visual effects that have populated social media of late. “Effect powders” are responsible for the chrome look, as well as the holographic nails. These powders, McConnell says, all work in pretty much the same way, but are just made with different materials. After a nail technician paints on a layer of gel color, they cover it in a special top coat, and cure it under a lamp just long enough for it to be barely sticky. Then they dip the little sponge in one of these powders, and rub it in.

For chrome nails, that powder is made of glass, metal, and pigment. “There’s no chrome in it,” McConnell says. “That would be completely illegal, because chrome is a heavy metal and the FDA would be down our throats about it. It’s more of a mirror nail.” And much like with a real mirror, the reflective effect is created when a metal—silver, in this case—is sandwiched between a base layer of paint (or polish in this case) and a clear protective layer on top (glass for a mirror; a clear, glossy polish for the chrome nails).

The powder doesn’t become a solid, even though it looks like it does; it’s just extremely fine and fills in extremely well. “If you could magnify it really, really large, you could see there’s spaces between each of the particles,” Schoon says, “but you can’t see it with your eye, because they’re too tiny.”

Different effects can be achieved with different pigments. Light Elegance has a bunch of different Pretty Powders, some of which give a chrome effect, some of which are pearly—that comes from mica coated with pigment, McConnell says—and some of which are holographic. The holographic effect (also sometimes called mermaid nail) is made with extremely fine bits of holographic polyester. This look can also be achieved, Schoon says, with a thin polyester film, “like the ribbons they wrap presents in at Christmastime.” But Light Elegance, at least, sells that polyester in a powder form that can be rubbed on the same as a chrome.

Tiny particles are also responsible for the cat’s-eye effect—but they’re incorporated into the polish itself, rather than spread on top as a powder. A polish formulated with iron oxide is painted onto the nail, and then the technician will hold a magnet over it. “It’s like the old Etch a Sketches,” Schoon says. “All the iron particles will line up, carry the pigments with them, and create a special effect.” The rearranging leaves a lighter stripe in the polish, which looks like the band of light in a cat’s-eye gemstone.

“Dip powder” manicures are yet another trend, and they’re exactly what they sound like: The color is applied by dipping the finger into a little pot of acrylic powder. It sticks because the base coat is basically cosmetic-grade superglue. Then you can repeat the process for as many layers of color as you want, and seal with a topcoat.

“All the brands are coming out with [dip powder] now,” Livesay says—but these products have been around since the 1980s. None of this chemistry, Schoon and McConnell stress, is especially new. Effect powders are the newest, having hit the market a couple years ago, they say, but Schoon characterizes all these effects as just creative uses of old pigments and ingredients.

And these effects are particularly social-media friendly. Not only do they look cool when they’re done, but the process of applying a chrome powder or a dip powder or holding the magnet to a cat’s-eye polish is fun to watch, and makes for a good YouTube or Instagram video.

“It’s a very soothing process to watch,” Livesay says. “You know how on Instagram, it recommends videos for you, and ‘oddly satisfying’ is one of the [hashtags]? It’s like people frosting a cake or something like that? I think it’s the same thing. I think it seeps into where our culture is at right now: It’s quick, it’s kind of mindless, but also it’s very comforting.”

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