Born in Grandin, North Dakota, in 1904, the artist Clyfford Still was among the first generation of Abstract Expressionists who, using emotive brushstrokes on large canvases, established a bold, evocative approach to painting in the years following World War II. Perhaps the movement’s most enigmatic practitioner, Still followed a rigorous methodology to produce potent paintings that convey a profound sense of energy and quiet strength. Unlike most of his peers, who bought paint from art-supply stores, Still typically mixed his paints by hand, grinding pigments and blending them with linseed oil. He believed that an artist’s work was best understood when viewed collectively—preferably in its entirety—and that, taken together, each piece told a story that was greater than the sum of its parts. (Still held on to nearly all of his output during his lifetime to prevent it from falling into the hands of someone who might not appreciate it, and rarely allowed his paintings to travel.)

To maintain this vision even in posterity Still stipulated in his will that his work be given to an American city that would create a museum dedicated to displaying and caring for it. After his death, in 1980, a number of cities jumped at the chance to steward the collection and, in 2004, Still’s widow, Patricia, selected Denver as its new home. She also left to the city her estate, which included additional paintings and Still’s entire archive. Seven years later, the Clyfford Still Museum (CSM) opened in Denver’s Golden Triangle District, adjacent to the Denver Art Museum (DAM)’s building by Gio Ponti (1971) and wing by Daniel Libeskind (2006) and down the street from the Michael Graves–designed Denver Central Library (1990). Designed by Brad Cloepfil, founder of Allied Works Architecture, the two-story CSM holds some 830 paintings and 2,300 works on paper—93 percent of Still’s oeuvre.

To celebrate CSM’s 10th anniversary, the institution recently mounted “A Decade of Discovery: Clyfford Still in Denver,” an exhibition that outlines what the museum has learned about the artist through exploring its holdings—such as unearthing undocumented paintings or that the translucent black substance used in certain works is actually powdered charcoal, not paint. These revelations, alongside personal correspondence, photographs, and other items from the museum’s archive, add further context around the artist’s character, work, and process. (On March 6, the last day of the show, CSM will present an in-person and live-streamed conversation, moderated by CSM director Joyce Tsai, about the intersection of art and architecture at DAM’s Sharp Auditorium. Panelists will include Cloepfil; Harry Cooper, senior curator and head of modern and contemporary art at the National Gallery of Art; and Spencer Bailey, co-founder of The Slowdown.)

Still’s daughter Sandra Still Campbell—who has long played a critical role in helping the museum and others better understand the artist—serves on CSM’s board and works closely with the institution to develop new ways of sharing his work with the widest audience possible. We recently spoke with Campbell to learn more about who Still was, why he painted, and how her appreciation of her father’s work has evolved.

How did your father view the act of painting?

Dad didn’t approve of spoon-feeding people. He valued effort and the lengths people would go to in order to make and consume art. Once, he hitchhiked to hear pianist and composer [Ignacy Jan] Paderewski play in person. At one point in the concert, Paderewski’s wife had to have the piano rolled off the stage because people were so fired up about hearing the real thing, and not some scratchy recording.

The people in that room understood the power of creative energy—and that’s what Dad wanted to give people with his paintings. He wanted to give people the richest experience he could. His purpose was to make something that would leave a human being fired up about life. Whenever I leave the museum, I feel like I’m a little bit off the ground. Energy comes back, and a sense of hope returns.

How did he approach the physical act of painting?

As years have passed, I’ve learned to appreciate my dad physically. He was six feet tall, very thin, had wiry strength, and unimaginable reflexes. To make the kind of paintings he did, he had to be highly coordinated and in good physical condition. He would walk up to the painting, step up on the ladder, and know exactly where he wanted to make a mark—one that would send someone’s spirit going. It required an incredible amount of hand-eye coordination, energy, and effort.

What was it like being around him while he worked?

We watched him live and we watched him paint. We lived through the angst that he suffered. We saw some pretty intimate moments when he was not at his best, wondering whether all his work was worth it. He used to have this 2 a.m. to 4 a.m. witching hour, which many of us have, where he would say, “Maybe I should just burn them. No one is getting this, and no one is appreciating this.” He felt that people wanted to make a product out of the paintings, or send them on some long journey. But he’d never let that happen.

When I [was younger], he was intimidating and had an energy that made every room feel too small for him. But he became a gentler person as life went on. He had this electrical force: Whenever I was cold, all he had to do was hold my wrist for about thirty seconds, and I would become warm all over. He had a physical fire that not a lot of people have.

How do you think the museum’s design contributes to the ways people experience his work?

It has visible storage rooms, which hold paintings that are not currently on view in exhibitions. There are two huge rooms on the main level of the museum where paintings, hung on movable rolling racks, can be rearranged whenever the museum wants—daily, weekly, monthly—allowing viewers to see that the body of work goes on and on and on.

Having all eight hundred canvases up at one time would be totally overwhelming. The goal of this museum was to make it big enough to cover a chronology: the early years, the forties, then the fifties, sixties, and seventies, plus a room for the pastels and works on paper. So the way it’s set up really works. It is tens of thousands of square feet of Clyfford Still paintings, an offering that makes you want more.

Has the way you see your father’s paintings changed over time?

It’s taken me years to appreciate what I saw him do. The pieces look so natural and spontaneous, but they weren’t at all. Dad knew exactly what he was doing.

I see the work as a whole now, not just as one painting that I was invited in to look at while he was working on it. I can see his sense of purpose, and why he was so stubborn with that one sentence in paragraph four of his will, which said that his paintings should not be broken up or transported. Dad always knew that the paintings were at their best when they were fresh. These are not bronze or marble blocks. This is boiled linseed oil. After a while, the oils on the painting would either evaporate, disappear, or go flat. So you want the paintings to last for as long as possible. This is why the paintings should only travel if there is an absolute purpose that benefits everyone.

Dad always said, “My art is not for children.” His art was serious business. At the opening of the museum, in 2011, there were children roaming around, kind of bored, looking at the earlier works. Once they got to the last room, which holds Dad’s later works, and stood in front of a bare canvas painting with gold-yellow flashes. They were literally dancing. They came alive, acting openly and uninhibitedly. I stood back and said, “Well, Dad was wrong!” He was only wrong once or twice in his lifetime. I tell this story because, if you come into the museum without any preconceptions, you’ll be surprised by how you react.