Catherine Ryu is on a mission to save your butt from saggy denim. Citizens of Humanity's latest line, Sculpt, includes body-contouring jeans that shape and lift without losing their stretch. Sure, it sounds like a mythological material-a golden fleece or Firebird feathers wrought by a jean genie-but we assure you it's real and will be in stores mid-September.

We got the scoop on Sculpt-plus, word on Ryu's personal denim collection and spiritual beach reading.

What about the Sculpt fabric makes it so good at shaping and lifting?

Ten years ago, a polyester yarn that's much, much stronger than cotton and elastic came into play. That technology has evolved a lot and is one of the components that gives the Sculpt fabric its power stretch and recovery. There's also the component of it being a blended fabric. It's a cotton-rayon blend that can drape luxuriously yet stretch and recover really well.

Fit is also a big factor.

From the waist measurement to the rise to the thigh measurement-we calculated all those things to make the fabric work. For the Sculpt capsule launch, we have our iconic Rocket skinny, which is our number-one fit, and our Fleetwood flare. The fabric is so drapey, we felt like it would give the flare a more trouser vibe versus a casual boot-cut feel.

Flares are huge right now. What's Citizens's take on the trend?

Flares are from the '70s, so we wanted to explore ways of reinventing them. We added flares to Sculpt to give them a more performance aspect and dressier expression. We also did some really authentic flares with worn washes and holes to give them attitude.

In light of California's drought, Citizens created a new wash process that uses way less water. Can you explain it? Do you use it to make Sculpt?

In addition to living through the worst drought in California history, we're a vertical company, which means we own our own laundries. We're always exploring how to make the laundry process safer for the environment and more efficient. We figured out we could do the full wash cycle in an ozone machine, which is a gas machine that reduces color, and it used one-tenth less water than the normal wash process. We can't do this process on all of our denim-unfortunately, it only works on dark washes. Even so, with Sculpt being the success that it is, we can use this innovation for a large part of our production. We're quite proud of that.

What's the next big innovation you're working on?

Now that we're fully immersed in stretch fabrics and Sculpt, we're going to switch everything up and study nonstretch fabrics. We're very inspired by the Levi's 501 and trying to achieve that look in a modern way. We were able to source a fabric that looked the part but has a modern, luxurious feel.

Citizens of Humanity uses both laser and stonewash abrasion to create specific wear patterns. Your denim collection must be pretty impressive. How much do you own? And what's your all-time favorite piece?

I have approximately 75 pieces of denim in my archive. There's always something new each season that I find that's interesting. But my favorite is a pair of 1947 Levi's XX. I found them at the Rose Bowl Flea Market at a vintage-denim dealer that I frequent.

Denim overalls-how do you style them?

I always love the juxtaposition of masculine and feminine vibes, so I would definitely try something a little bit more feminine or sexy on top, maybe an off-the-shoulder T-shirt or Edwardian blouse with heels.

As an Angeleno, you must hit the beach quite a bit. What's your current beach read?

There's a book called Autobiography of a Yogi about a yogi that brought yoga to the West. I heard Steve Jobs's family was giving it away at his funeral, so I was really curious about it. He read it throughout his whole life, so I wanted to read it. I fell in love with it. It's just so warm, honest, humorous, practical and human. It was published in the '40s, but it's still so relevant. I highly recommend it.

- Jessica Zech