When Patricia Arquette signed on to make “Boyhood” with writer/director Richard Linklater, playing Mom to a boy named Mason (Ellar Coltrane) who would literally grow up on the screen over 12 years of filming, she knew it was highly likely she was getting into something special.

Linklater had at that point only made the first installment of his “Before” trilogy, 1995′s “Before Sunset.” He’d go on to release its sequel “Before Sunrise” in 2004 and “Before Midnight” in 2013. But the Texas native behind “Slacker,” “Dazed and Confused” and “School of Rock” was already known as a wildly creative force who could move easily between art films, cult fun and mainstream comedy.

Both she and Linklater had kids (hers was 12, his was 6 and would go on to play Arquette’s daughter, Samantha, in “Boyhood”), and she was excited by the concept of making something that might feel like a human version of “that high-speed photography with the seedlings” that she loved so much. She was looking forward to aging on screen with Ethan Hawke, who plays the children’s wandering father.

But even as she became convinced over those years of filming that she was part of a masterpiece, a unique project that had no equal in American filmmaking, she wasn’t sure if audiences would embrace it.

“It is not in any way your typical movie,” she said during a recent phone interview. “Rick threw out the whole conventional wisdom about how to write a movie that would make money, and what demographic is worthy and which doesn’t matter. I first saw it at Sundance in a theater with 1,200 people. And I turned around and a 6-year-old was crying and a 20-year-old was crying and a 40-year-old was crying.”

“Boyhood” has been so favorably reviewed that it has a 99 percent positive rating on Rotten Tomatoes and 100 percent on Metacritic. Variety, not exactly the gushiest of industry publications, proclaimed that Linklater should get the 2014 Oscar for best director. The movie finally came to Maine this week, playing at Railroad Square in Waterville, and is expected to play at select theaters, including the Eveningstar in Brunswick, starting Friday. We talked sequels and Texas haircuts with Arquette.

Q: How did the filming work, logistically? Did you know what the story arc would be?

A: We’d shoot for three or four days every year. But if you put together all the time they had to do in pre-production every year before that, it added up to a whole year of it. And he (director Linklater) had two years altogether in post-production.

It’s always a blind faith exercise when a director tells you he doesn’t have a script.

Rick did tell me, ‘You are going to get remarried and he is going to be a professor.’ But mostly he would call a few weeks ahead (of the annual filming) and say, ‘Start thinking about this: you are going to have this scene with the kids and you’re going to be moving and they’re going to be angry.’ And I’d think about my own experiences with my mother. Then we would come together and read the scene as he had written it.

We’d talk it through and then Rick would curate lines from everybody’s contributions and we’d shoot it the next day.

We were all just showing up because we wanted to. Even the crew kept coming back. They would move up in their careers, starting as PAs (production assistants) and become ADs (assistant directors) and yet they would come back and be a PA on this movie.

They were that committed.

Q: Was there ever a point when you thought, this project may go by the wayside? Fall through?

A: I am not a huge worry- wart. I am sort of an adventurer. The reality of it is we could have lost funding at any point.

There was one year where IFC (IFC Films, which produced “Boyhood”) closed their books for the year without budgeting anything for us. And Rick said, ‘My house burned down, and I am just going to use my insurance money.’ He is completely humble and a lover of the experience. He is just such a cool cat.

Q: Did you watch the footage as it accumulated?

A: Rick always made it an option for me, and Ethan watched a lot, but I didn’t really want to see it then. I just wanted to see it as an audience member at the end.

I did see some of it after five years of filming and (after that) I felt envious of the audience who would be seeing it without knowing anything about it.

Q: Even your television series “Medium,” which ran for six years, can’t quite compete with 12 years with a character. How close did you feel to Mom?

A: It was so improvisational that I had a part in saying who this character was and what her life references were, so I felt very close to her. The weird thing is, as an actor you nurse these babies, these characters inside yourself. You do the preliminary work of filling in their histories and developing them.

What I felt excited about discovering was this part of it – these characters have blind spots. There’s a scene with one of her boyfriends where he starts commenting on Mason’s nail polish. Me and Rick had a long conversation about why doesn’t she say something at this point?… In my life, I would have said, ‘I don’t want you impacting my kid like that.’ But she’s really through with the wars. And if later Mason had said, ‘Why were you with that (expletive)? She’d have been like ‘No, that didn’t happen! I would have said something if that happened in front of me.’ She believes that.

Q: Is it strange for you to watch yourself evolve over the years on film this way? The changing haircuts, the aging process?

A: A lot of times my haircuts would be dictated by this movie! Oftentimes I got my hair cut in Texas during filming. It was so hot. And there is such a restlessness to her, it made sense that she’d change her hair a lot. Then I would have these haircuts on “Medium.”

Q: Do you think this is Linklater’s masterpiece?

A: I do. And I always knew I was working on something beautiful. The thing is, throughout filming, me and Ethan would talk a blue streak about this movie and people’s eyes would just glaze over. We’d be talking about masterpieces and I would say, I am doing one right now.

Q: And they didn’t believe you, that you, the star of “True Romance,” “Lost Highway” and Linklater’s “Fast Food Nation” were involved in a masterpiece?

A: No. And I’d think, why do you think you can put me in a box? The older I get – and this is part of what I wanted to see realized in her (the character of Mom) – is how you start detaching from other people’s perceptions of you. And you recognize how wrong they are. The thing is, I knew we were making something truly beautiful. Really human and so special to all of us.

Q: Would you go back to make another installment? Called say, “Manhood”?

A: A lot of people have told Rick he should make a sequel. Michael Apted (the director of the “Up” series, which so far has tracked a group of British kids from ages 7 to 56 in seven-year installments) saw the movie and said, ‘You’ve got to keep going.’ But I don’t think Rick wants to think about that now. It’s like when you’re birthing a baby, like asking a woman when she is crowning, ‘Don’t you want to have more kids?’