Hawke hails 'unique' Boyhood movie
The Gattaca actor and Patricia Arquette star in the film, which was shot over the space of 12 years, beginning in 2002.
"It's just completely unique. I don't know anybody else that's done this either. It's a strange thing to try to do. My first scene in the movie, I was 32 years old. I'm going to be 44 this year," Ethan said.
The drama, which premiered at the Sundance Film Festival, follows the relationships of a divorced couple (played by Ethan and Patricia) and their son (Ellar Salmon) over the 12-year period.
"You fly by the seat of your pants. It's fun. Every other movie I've made in my life is like something else - this is like nothing else," Ethan continued. "We're in the weird part of the water where you don't really know how to swim."
The 43-year-old - who was reunited with Richard, the filmmaker behind the Before Sunrise trilogy on Boyhood - revealed he gained some new knowledge about himself, but explained: " Yeah definitely, but if I'd said anything, it would be corny.
"I didn't learn anything that can be boiled into some nugget to be handed out. Hopefully, whatever we learnt will be on the screen and people can take from that what they want."
Richard said he is "happy" that the project is completed.
"I got to think about it every year for a while. I probably worked about two months a year on this and then was able to do other things," he said.
"It was a commitment. I was trying to tell the story in a new way and this was what was required. It wasn't really an experiment, it was the plan."