Let’s go back, wayyyy back, to October 2010— two whole years ago.

One of the first things that caught my attention, just getting off a plane for my first Paris Fashion Week for ITG (or ever), was a pair of fashion students perched outside the Sonia Rykiel show: Sofie and Natalia. I knew they were French…you could just tell. Partly because of the way they carried themselves (too cool for school), partly because you couldn’t put your finger on who made anything they were wearing and they looked great, but mainly, because of their hair. It was long, kind of wavy-meets-languid, and just a little bit…fuzzy. It’s that same quality of hair that most models seem to have miraculously been born with, and that same quality that, a lot of the time, hairstylists spend hours trying to replicate or (or resuscitate) for the runway. It’s carefree, it’s natural…it’s Jane Birkin Hair. And, as I finally discovered thanks to an eye-opening chat with actual French models, it all comes down to—drum roll here—brushing for your hair type.

Backstage at the Jean-Paul Gaultier show two weeks ago, everybody’s favorite catwalking Frenchies Constance Jablonski (with nothing more than a Velcro roller in her hair, courtesy of Guido, preparing for her turn down the runway as ‘Jane Birkin’) and Sigrid Agren (in full ‘Madonna’ mode) were killing time with Canadian pal Alana Zimmer and yours truly when the subject of hair came up. “Well, for French girls, you don’t do anything to your hair,” Constance said. “You know what I mean?” No. “I really don’t!” She continued, “I never brush my hair—I don’t have a brush. I would never brush my hair.”

Alana nodded in agreement, “I own one, but I don’t use it. I have wavy hair, and when I brush it, it destroys the waves.”

“Me too,” Constance said. “I have waves. And waves never need to be brushed. But I think it depends on your kind of hair. So for certain hair… I think straight hair needs to be brushed, maybe.” Okay, now we’re getting somewhere.

Constance : Yeah, like the girls will ask me, ‘Do you have a brush in your bag?’ And I’m like, ‘No, why would I have a brush?’ [Laughs] I do have a comb to do a part, that’s it. Just a straight, little comb.

Alana : I let my part fall wherever it feels like. [Laughs] ‘Cause I have so much hair, if I brush it, it gets so wide at the bottom… and I just look like a big triangle. I just comb it in the shower, with a wide-tooth comb.

Constance : With conditioner, always. And then I dry it with a towel, quickly…and that’s it!

Sigrid : Me too, I comb it in the shower.

Constance : But you don’t brush it, right? I mean, you don’t carry a brush in your bag?

Sigrid : I do!

At which point Sigrid opens the flap of her Chanel bag and takes out a tiny wooden, boar-bristled brush.

Constance & Alana : Noooo! [Laughs]

Sigrid : I have to! My hair never goes frizzy; it’s dead straight. It gets really tangly if I don’t brush it. I have straight, straight hair so it doesn’t matter if I brush it or not. If I don’t brush my hair it looks like… flat.

Frida Gustavsson [after overhearing the convo, chimes in] : For me, it tangles in two seconds. Alana, do you have a brush in your bag?

Alana : Never. I just wash my hair every three days, and use a dry shampoo in between.

Constance : Because I do sports, I wash it two times or three times a week—then I wash them after sports. [Ed. note: French girls tend to refer to hair as “them,” not “it,” in a terribly endearing way.] But if I don’t do sports and I don’t do work, it can stay clean for, like, five to six days. I swear! [Laughs]

Sigrid : Nooo… I wash it every other day.

Constance : But it’s because I have dry hair, so it doesn’t get greasy. But I also have dry skin, which is bad. Everything is dry. I need to moisturize. And the other thing is, I never [blow] dry it. I just wash it and let it dry by itself.

Alana : But naturally. If it’s cold out and it’s wet, I’ll just blow it a bit.

Constance : I would never blow-dry my hair.

Not even in the dead of winter?

Constance : Well, in the dead of winter, in that case… I would wash them at night. [Laughs]

So there you have it: washing, brushing, and blow-drying rules to live by, straight from the girls with some of the best hair in the biz. My M.O.? Wash, condition (no comb), air-dry, 3 mornings a week, wet hair out the door—weather be damned.

—Emily Weiss

Sigrid Agren [1], Constance Jablonski, and Alana Zimmer [3] photographed by Emily Weiss backstage at Jean-Paul Gaultier on September 29th, 2012.