Dakota Johnson reveals thongs were superglued to her body while filming 'Fifty Shades Freed'

Dakota Johnson is sharing behind-the-scenes secrets from 50 Shades Freed.

In a new interview with MarieClaire.com, the 28-year-old actress opens up about the awkward, "really unsexy" things she had to do (and wear!) while filming the third and final installment of the erotic movie franchise.

Johnson, who portrays Anastasia Steele, aka "Mrs. Grey," admits that filming the provocative sex scenes with Jamie Dornan (Christian Grey) were "never easy."

"It's not casual and it's not fun," she explains. "It never got easy."

The brunette beauty says that there were plenty of uncomfortable moments throughout filming, like the fact that she had to have strapless thongs superglued to her body.

"I had these sort of strapless thongs that had glue on them. It's not glue, but it's sticky," she reveals. "They're, like, basically if it were a nipple pastie, but underwear. But it's only sticky at the top, it's not sticky the whole way. It would also come off because the adhesive would wear out, so then they would superglue it to my body so that it wouldn't fall off. And I would wear two of them."

See photos of Dakota Johnson at "Fifty Shades" premieres:

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Evolution of Dakota Johnson at 'Fifty Shades' premieres
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Evolution of Dakota Johnson at 'Fifty Shades' premieres
LONDON, ENGLAND - FEBRUARY 12: Dakota Johnson attends the UK Premiere of 'Fifty Shades Of Grey' at Odeon Leicester Square on February 12, 2015 in London, England. (Photo by Anthony Harvey/Getty Images)
LONDON, ENGLAND - FEBRUARY 12: Dakota Johnson and Jamie Dornan attend the UK Premiere of 'Fifty Shades Of Grey' at Odeon Leicester Square on February 12, 2015 in London, England. (Photo by Mike Marsland/WireImage)
LONDON, ENGLAND - FEBRUARY 12: (SUN NEWSPAPER OUT. MANDATORY CREDIT PHOTO BY DAVE J. HOGAN GETTY IMAGES REQUIRED) Jamie Dornan and Dakota Johnson attend the UK Premiere of 'Fifty Shades Of Grey' at Odeon Leicester Square on February 12, 2015 in London, England. (Photo by Dave J Hogan/Getty Images)
BERLIN, GERMANY - FEBRUARY 11: Actress Dakota Johnson attends the 'Fifty Shades of Grey' premiere during the 65th Berlinale International Film Festival at Zoo Palast on February 11, 2015 in Berlin, Germany. (Photo by Dominique Charriau/WireImage)
BERLIN, GERMANY - FEBRUARY 11: Actress Dakota Johnson and actor Jamie Dornan attend the 'Fifty Shades of Grey' premiere during the 65th Berlinale International Film Festival at Zoo Palast on February 11, 2015 in Berlin, Germany. (Photo by Target Presse Agentur Gmbh/Getty Images)
NEW YORK, NY - FEBRUARY 06: Actors Jamie Dornan (L) and Dakota Johnson attend the 'Fifty Shades Of Grey' New York Fan First screening at Ziegfeld Theatre on February 6, 2015 in New York City. (Photo by Jamie McCarthy/WireImage)
HOLLYWOOD, CA - FEBRUARY 26: Actors Jamie Dornan (L) and Dakota Johnson speak onstage during the 89th Annual Academy Awards at Hollywood & Highland Center on February 26, 2017 in Hollywood, California. (Photo by Kevin Winter/Getty Images)
LONDON, ENGLAND - FEBRUARY 09: Dakota Johnson attends the 'Fifty Shades Darker' - UK Premiere on February 9, 2017 in London, United Kingdom. (Photo by Samir Hussein/WireImage)
LONDON, ENGLAND - FEBRUARY 09: Jamie Dornan and Dakota Johnson attend the 'Fifty Shades Darker' - UK Premiere on February 9, 2017 in London, United Kingdom. (Photo by Samir Hussein/WireImage)
MADRID, SPAIN - FEBRUARY 08: Dakota Johnson attends the 'Fifty Shades Darker' premiere at Kinepolis Cinema on February 8, 2017 in Madrid, Spain. (Photo by Fotonoticias/FilmMagic)
US actress Dakota Johnson and British actor Jamie Dorman pose at their arrival to the presentation of 'Fifty Shades Darker' held at Kinepolis cinema of Madrid, Spain on 08 February 2017. The film will screen upcoming 10 February. (Photo by Oscar Gonzalez/NurPhoto via Getty Images)
MADRID, SPAIN - FEBRUARY 08: (L-R) Dakota Johnson and Jamie Dornan attend the 'Fifty Shades Darker' premiere at Kinepolis Cinema on February 8, 2017 in Madrid, Spain. (Photo by Fotonoticias/FilmMagic)
HAMBURG, GERMANY - FEBRUARY 07: US actress Dakota Johnson (daughter of Melanie Griffith and Don Johnson) attends the European premiere of 'Fifty Shades Darker'(German title 'Fifty Shades Of Grey - Gefaehrliche Liebe) at Cinemaxx on February 7, 2017 in Hamburg, Germany. (Photo by Isa Foltin/Getty Images)
HAMBURG, GERMANY - FEBRUARY 07: British actor Jamie Dornan and US actress Dakota Johnson (daughter of Melanie Griffith and Don Johnson) attend the European premiere of 'Fifty Shades Darker'(German title 'Fifty Shades Of Grey - Gefaehrliche Liebe) at Cinemaxx on February 7, 2017 in Hamburg, Germany. (Photo by Isa Foltin/Getty Images)
LOS ANGELES, CA - FEBRUARY 02: Actress Dakota Johnson arrives at the premiere of Universal Pictures' 'Fifty Shades Darker' at The Theatre at Ace Hotel on February 2, 2017 in Los Angeles, California. (Photo by Axelle/Bauer-Griffin/FilmMagic)
LOS ANGELES, CA - FEBRUARY 02: Actors Jamie Dornan and Dakota Johnson arrive at the premiere of Universal Pictures' 'Fifty Shades Darker' at The Theatre at Ace Hotel on February 2, 2017 in Los Angeles, California. (Photo by Axelle/Bauer-Griffin/FilmMagic)
LOS ANGELES, CA - FEBRUARY 02: Actors Jamie Dornan and Dakota Johnson attend the premiere of Universal Pictures' 'Fifty Shades Darker' at The Theatre at Ace Hotel on February 2, 2017 in Los Angeles, California. (Photo by Alberto E. Rodriguez/Getty Images)
PARIS, FRANCE - FEBRUARY 06: Dakota Johnson attends the 'Fifty Shades Freed - 50 Nuances Plus Clair' Paris Premiere at Salle Pleyel on February 6, 2018 in Paris, France. (Photo by Stephane Cardinale - Corbis/Corbis via Getty Images)
Actor Jamie Dornan (L) and actress Dakota Johnson pose as they arrive to attend 'Fifty Shades Freed - 50 Nuances Plus Claires' Premiere at Salle Pleyel in Paris on February 6, 2018. / AFP PHOTO / PATRICK KOVARIK (Photo credit should read PATRICK KOVARIK/AFP/Getty Images)
PARIS, FRANCE - FEBRUARY 06: Jamie Dornan and Dakota Johnson attend 'Fifty Shades Freed - 50 Nuances Plus Claires' Premiere at Salle Pleyel on February 6, 2018 in Paris, France. (Photo by Pascal Le Segretain/Getty Images)
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"It's not painful, I mean, it's barely anything," she adds. "But I guess you have some sense of being covered. It's f**king bizarre."

While Johnson had to film plenty of difficult scenes for the franchise over the years, she says the hardest one was hands down a Red Room sex scene with Dornan for 50 Shades Freed, which is in theaters now.

"I was handcuffed with my arms and legs to the gate. It's like a fence thing that comes down. And I was blindfolded," she recalls. "And it was kind of shocking, because I didn't realize that no matter how prepared or rehearsed I was, when your senses are taken away like that, you can't control the way your nervous system will react. So, it was really tricky to navigate that scene. It was kind of difficult."

Johnson admits that she and Dornan did have some help for the extremely difficult scenes, however.

"Most of [our preparation] is just really figuring out exactly how were are going to accomplish the scene beforehand, so that there's not a lot of waiting around while we're both vulnerable," she says. "But, if something is very, very difficult, it's sometimes necessary to have a shot of something strong beforehand."

Earlier this month, ET exclusively caught up with Dornan at the Le Grand Hotel in Paris, France, where he opened up about what it's like saying goodbye to the character that's made him a household name.

"It's tough in some respects, but it's also really nice and kind of bittersweet, I guess," he shared. "I think when you finish any movie or TV series or whatever, you've invested so much [time] into the character and the job itself and the other actors and the crew."

"That's sort of tenfold if it's a sequel or trilogy of films," he continued. "For the most part, we had the same crew back [and] obviously the same actors back, so you're that much more invested in these people and their lives and that much more closer to them. So, it makes it harder to say goodbye."

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