Six seasons and 130 episodes in, the four main characters of Pretty Little Liars are still being tortured by a potential murderer. That’s one reason why people are tuning in; the other, as any fan will tell you, is wardrobe. The girls wear heels to high school and waterfall braids to the interrogation room. Lucy Hale’s every haircut is written up all over the Internet. She has a bob – that’s a lot of articles.

We talked to Kim Ferry, the head department hair stylist, about how she concepts looks for a show that switches seamlessly from dark to light. More importantly, we got some hair tips.

YouBeauty: What’s your process like for developing each hairstyle?

Ferry: Our styles are essentially dictated by what the characters are doing. If they’re underground being tortured, that’s a different look from when they’re dressed up for school. It’s been a challenge because we always want to have great hairstyles, but sometimes we have to pull back and make sure that it’s instructive with what’s going on in their lives.

That’s one of the fun things about Pretty Little Liars – it’s true to life but the characters always look good. How do you toe that line?

It’s tricky because it’s a heavy beauty concept show. For example, if they’re just waking up they look good. We call it “sleuth mode.” When a character is snooping around an abandoned barn, we need to put her in something like a loose bun or have her hair tucked, so her hair’s not falling in her face as she looks down. We love having their hair down. I love having their beach waves. It’s pretty and it’s iconic to them now, that loose fun hair. We alter and switch it a little bit depending on scripts.

On such a popular show with a devoted fanbase, I imagine you can’t just decide ‘well I want to chop off Hanna’s hair today.’ What’s the process for drastic hair changes?

We have a change in our show coming up – I’m sure everybody knows we’re jumping ahead. We’re going to do some really big changes. We shot it but it’s not out there yet. You’re going to see some great hair changes on the cast. It’s definitely a group effort. The writers and producers are creating a look, so it’s a conversation with them about where it’s going. We go to a meeting with makeup and wardrobe and get on the same page with the director and writer about what the looks are going to be, what dresses are going. If they have a job in the future, if they’re heading in a certain direction, what hair makes sense. If they’re serving food, it makes sense that their hair is back. We all work together.

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What do you think is the most drastic change or intense style that you’ve created?

I got a lot of response from the prom episode that just aired. Everyone seemed to love Hanna’s hair. All the girls looked stunning. The twist that I did was a big hit. Aria had a little bow in her hair. I loved her short cut, which came about because she wanted to get a haircut. We talked to the producers and the writers wrote it into the script. Sometimes hair changes come about that way, other times because of jumps we’re doing. If you could see my trailer – there are so many hairpieces. We do flashbacks a lot, we have stunt doubles, photo doubles, so I have to build on someone else.

What are your favorite products to use?

We really don’t use hairspray a lot, which shocks some people. We use Oribe Dry Texturizing Spray and we always try to use a good setting spray, White Sands Liquid Texture Medium Hold Thermal Styling Spray. And we definitely put oil on the ends to help them look good. You know the heat, the lights, it takes a toll, and we do it every single day. We also use irons – we have 1” curling irons and flat irons. I curl vertically and make sure not to hold it super long and pull it out with my fingers to make it soft. We start from the nape and curl up, which gives a great, gentle wave.

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