The hero of Matt Reeves’ The Batman boldly does something none of his previous onscreen counterparts have done: When the cowl is off, he wears a heavy, smokey eye.

While Robert Pattinson’s darkly lined eyes certainly make for a compelling, unforgettable look, that aspect of his character design isn’t all about the aesthetic. (To be fair, it is a lot about the aesthetic.) The eye makeup has a practical purpose: Bruce Wayne needs to cover the area around his eyes in order to completely conceal his face while wearing his black cowl. Other actors playing Batman in live-action films usually also wore these raccoon eyes, but The Batman is the first to acknowledge that the illusion of darkness requires some cosmetic skills.

As makeup designer Naomi Donne tells Polygon, director Matt Reeves really wanted a makeup look that focused on how Batman looks immediately after taking off his costume.

“Matt was really keen that there were remains of [the eye makeup] when he took his cowl off,” she explains. “So we pushed that. We actually took the cowl off and looked at what was left, and we used that. It’s really hard to get black eye makeup off, and we used that.”

It was a process of trial and error, Donne says, to get that perfect blend of dark eye makeup that would look good, but also stay on. Between the film’s rainy setting, the sweaty costume, and the intense action scenes, they needed something with a lot of staying power. In the end, Batman’s perfectly calibrated emo look was a mixture of pigment, a creamy eyeliner, pencil, and a liquid paint makeup.

“And then,” she says, “to brighten it up, we used this lightly sparkly pigment to give it a bit of light, so that it reflected lights in the same way his Batsuit would’ve.”

While the dark eyeliner certainly brings to mind emo and goth subcultures, Donne says Reeves’ touchpoint for Batman’s look came from a different specific source: Kurt Cobain. Reeves previously revealed how the Nirvana singer inspired his take on the Caped Crusader, and how he leaned more on a tortured Bruce Wayne instead of a playboy millionaire. In fact, that connection led Reeves to cast Robert Pattinson. It makes natural sense that the deeper character threads tying Kurt Cobain and this version of Bruce Wayne would also extend to their visual aesthetics. After all, Cobain rocked the black-eyeliner look in the ‘90s — even if it wasn’t as messy as Bruce Wayne’s getup in the movie.

“I loved that at times it was very smudged and running down his face, and at times it was just a smokey eye. But at all times it was never clean. It always came from the remains of the cowl,” says Donne. “It was the way of Batman lingering in Bruce Wayne after he’s taken his costume off.”

But as much as we can wax on about the metaphors in eye makeup and how the lingering specter of Batman will forever haunt Bruce Wayne, Donne boils it all down to a universal truth: “It also looked dead sexy. Men in black eye makeup look really good.”