Meryl Streep Talks Acting with Daughter Mamie Gummer in Ricki and the Flash: 'She's the Real Deal'
08/04/2015 AT 01:00 AM EDT
"She's brave and fearless and funny and free," Streep, 66, said at the world premiere of Ricki and the Flash on Monday in New York City. "She's a free talent. It doesn't have any cover-up – she's the real deal."
Gummer, 32, plays the daughter of Streep's rock-star character, Ricki. The pair struggle through a strained relationship caused by Ricki putting her music career before her family. The relationship between on-screen mother and daughter raised some concerns for Gummer, who didn't want to hurt Streep's feelings in real life.
"There's this one scene where I really was quite eviscerating and I was worried about if my words actually wounded her, but after the first take, I looked over and she just had this big grin on her face, so that was a pleasant surprise," Gummer told PEOPLE.
When asked about the process of working with family, Gummer said that one needs to be very good at compartmentalizing as an actor.
"Luckily my costar, she knows how to do that quite well," Gummer said about her mother.
She also dished that the boots Streep wore for the film were actually Gummer's. While her wardrobe may have been a 10 thanks to her daughter, Streep didn't exactly arrive on set as a guitar goddess. But costar Rick Springfield said she more than made up for it in other ways.
"Her guitar skills as far as actually playing – probably a 3," Springfield told PEOPLE. "But what she brings, people don't realize how hard it is what she did. Every time the camera's on her, she's on the right chord. She knows what she's doing. So it's absolutely remarkable that she does what she does."
Ricki and the Flash premieres nationwide on Aug 7.
Reporting by HAIWEN LU