Jamie Dornan, who plays Christian Grey, and Dakota Johnson, who plays Anastasia Steele, sat down with Glamour and opened up about the most uncomfortable scenes in Fifty Shades of Grey to shoot. The co-stars will appear on the cover of the March issue of Glamour on Feb. 10.

Johnson and Dornan both commented on the scenes in the infamous Red Room, or Grey’s room for submission and bondage. Johnson called those scenes the “most vulnerable scenes in the movie.” She said that the set was “very closed.” Only the director and the two leading actors were in the room.

Dornan said that some of the scenes were very uncomfortable, and he had to do things to Johnson that he would “never choose to do to a woman.” He added that he was aware that the scenes were not easy for her either. Johnson said that Dornan was always a gentleman.

She admitted that it was stressful to be tied to a bed naked. She added that being tied to a bed naked when the director yells “cut” is even worse. She said that Dornan would be the first to cover her with a blanket.

The most stressful scene for Johnson was when Dornan had to use a flogger on her, according to Time. She called it “emotionally taxing” and she just had to “get used to it.” She said that at first, she said “Oh my God, this is the worst thing ever.” Eventually, she would just say, “All right, let’s get on with it.”

Although the scenes in the Red Room were difficult, Dornan said that the most difficult scene for him was the scene in which Anastasia had to interview Christian. He said that getting across the pair’s initial connection was imperative, and they took two days to film the scene.

Fans will get a closer look at the film before its release in Glamour, but a new clip from the movie was released Monday that provides an even closer look. The clip shows Anastasia Steele helping Christian Grey find cable ties, masking tape and rope the hardware store she works in.  Today will continue to release short film clips throughout the week.