In recognition of her extraordinary efforts bringing Tammy Faye Bakker to life in new movie The Eyes of Tammy Faye, actress Jessica Chastain has quite deservedly been nominated for an Academy Award for Best Actress. Transforming into the infamous televangelist and singer, Chastain had been working hard to give the project a screen treatment for many years, and put even more work into bringing this unique character to life - not just in terms of manner and singing (something Chastain had not done since college), but also totally transforming her looks to become the Christian superstar. Turning herself into Tammy Faye each day on set was enormously time-consuming in itself - hair and makeup could sometimes take as many as five to seven hours before Chastain was camera ready.

Related: Why Did 'The Eyes Of Tammy Faye' Bomb At The Box Office?

In light of this astonishing commitment to the part of Tammy Faye, let's take a look at how Jessica Chastain prepared for her iconic role as PTL founder Tammy Faye Bakker.

6 The Nerves Drove Jessica Chastain To Hit The Bottle

Taking on this challenging role placed immense pressure on Chastain, who has half-joked that she sometimes needed a drink to get through her scenes - especially when she was required to sing.

"My preparation for singing was bourbon. I'm not even gonna lie," Chastain said on The Awardist podcast. "I was so scared."

"I'd never done that before, and I was like, 'I need a drink because I'm so freaked out.' It was [for] medicinal purposes," she added, winking, "but that's actually what really helped me get beyond it."

Related: Forget Leonardo DiCaprio: Jessica Chastain Truly Is Unrecognizable As Tammy Faye Bakker

5 Jessica Chastain Had To Learn How To Sing Like Tammy

Jessica had not sung since her college days at Juilliard, so singing all of Tammy's songs in the movie was a big ask. Tammy, who "ministered through song", had a unique voice which Chastain had to carefully mimic. "She's at an 11 from the moment she starts singing the song, and she just gets bigger and bigger and bigger and bigger and louder. For a shy, reserved person, it's a nightmare. But I had to do it."

Long rehearsals and time spent with a professional music producer helped Chastain develop her voice: "We have 31 songs we're singing," Chastain says. "We did six weeks of rehearsals in New York. Then I went to Nashville and did 10 days straight working with [music producer] T Bone Burnett."

4 Jessica Chastain Had To Throw Herself Completely Into Tammy

Becoming somebody as outlandish as Tammy Faye Bakker couldn't be done by halves. It became all-consuming for Chastain.

Of Tammy, Chastain said: “She never really did anything halfway. She didn’t have an ounce of being cool or being aloof about her. So I just felt like I couldn’t dip my toe in or be cool and aloof in the performance. I had to jump in the most wild, extreme way. Because that’s how she lived every moment.”

Related: 10 Things Fans Can Expect From Jessica Chastain's Tammy Faye Bakker Biopic

3 Jessica Chastain Carried Out Extensive Research

Bringing Tammy Faye realistically to life required hundreds of hours of research. Chastain found magazine articles about the late Tammy Faye Messner (formerly Bakker), and studied old photographs and TV appearances.

Often she used her time waiting for hair and makeup to be completed to fine tune her performance: “I was constantly watching videos of her, listening to her voice. I was using it as a runway. Sometimes when you’re playing a character, you get a 30-minute runway, and then you take off and you’re shooting. My character had an extra-long runway.”

2 Even Tammy Faye's Hair And Make-Up Was Studied Carefully

Tammy Faye was known not just for her big voice, but also for her big hair and even bolder make-up. Chastain's unrecognizable transformation required a team of makeup, hair and wardrobe artists.

Justin Raleigh, the film’s prosthetic makeup designer, had to design specialist facial prosthetics: “Jessica wanted to be lost within the role and to really embody Tammy without completely obliterating Jessica as well,” Raleigh said. “We had a really careful dance of how much prosthetics we were going to use or not.”

“Working in reverse, once we established what we had to do for the 1980s and ’90s, the only way to make the rest of it work would be to add prosthetics to her younger look,” Raleigh explained. “We had to keep that level of continuity, anatomically speaking, throughout the entire film.”

1 Jessica Chastain Wore Body Suits And Had Her Make-Up Applied With Marker Pen

During the 1960s and ’70s scenes, Chastain wore prosthetics on her cheeks and a covering for her distinctive chin dimple, in addition to wearing tape to pull up her nose tip upwards. In later 80s scenes, Chastain had to wear a bodysuit, full neck and upper lip prosthetics. For the ’90s she wore fake eye bags.

Artists also had to recreate Tammy Faye's make-up, which in her later years was permanently tattooed on. Faye's eyeliner, eyebrows and lip liner were recreated with marker on Jessica. Lashings and lashings of mascara (on top of fake lashes) also helped to create the iconic ultra-glam look.

Next: Jessica Chastain Rushed To Hospital After Terrifying Accident On Set Of 'The 355'