Jessica Chastain says one of her scenes in 'It Chapter Two' is the bloodiest scene in horror movie history.

Jessica Chastain

Jessica Chastain

The 42-year-old actress is playing the adult version of Beverly in Andy Muschietti's sequel to the hit 2017 film based on Stephen King's iconic 1986 novel, and she has promised gore fans will get their money's worth.

Speaking at a panel for 'It Chapter Two' at the San Diego Comic Con, Chastain said she had been told the film had broken a record: "That's what I was told on set. It wasn't real blood, obviously. 4,500 gallons of fake blood."

The 'X-Men: Dark Phoenix' star revealed she ended up "immersed" in the huge amount of fake blood, but she admitted it was her own decision as she wanted to surpass another King creation.

She added: "I was immersed in it. Basically it's kind of like a mixture of KY Jelly with red dye. The director was telling me about the scene and he said, 'It's only going to go up to your chest.'

"And I said, 'This is our opportunity to really make something crazy. Let's do 'Carrie' on steroids.' I fully went in the blood, which I regretted a lot afterwards. I was pulling stuff out of my eyeballs the next day."

Co-star Bill Hader, who plays the adult Richie Tozier, explained that whenever Chastain was dunked in the blood, there was a noise that would tell him and his co-stars they were about to start filming.

He said: "When they would pour the blood on Jessica, it was incredibly cold. And so when that happened we knew that was our time, that we were about to shoot any minute.

"So we would hear this sound [makes noise of chattering teeth] and then we'd be like, 'Well, alright, here we go!'"

The movie - which also stars James McAvoy as Bill, James Ransone as Eddie and Andy Bean as Stan - is set for a September 6 release.