As she began each of her intricate and expressive portraits, Georgianna Nyman Aronson brushed layer after layer of paint onto the canvas, slowly summoning her subject from the colors.

“Soon, almost the way a lump of clay would begin to form into something recognizable in a sculptor’s hand, you could begin to see a figure in this space. It was almost like a blurry lens focusing sharper and sharper,’’ said her son, Ben, who also is an artist.

“Every day there would be more there until one day there was an astonishing thing to see — a consciousness in the painting,’’ he said. “The person in the portrait was looking back at you, conscious. She was able to get these people to inhabit her paintings.’’

An artist whose talents were widely sought, and whose portrait series of US Supreme Court justices is part of the collection at New England Law-Boston, Mrs. Aronson died of uterine cancer June 10 in Brigham and Women’s Hospital. She was 86 and had lived in Sudbury.

After a childhood disrupted by the divorce of her parents, followed by years in foster care, she built a life that was as finely crafted as her portraits. Mrs. Aronson’s twin loves of music and art formed a creative counterpoint as she performed and painted.

A classically trained singer, she often had German lieder playing in the background while she painted in her studio. “She had a unique voice in both art forms,’’ her son said. “She never wanted to have to choose between the two. She felt they were externalizations of the same creative spirit.’’

Bruce Herman, who holds the Lothlorien distinguished chair in fine arts at Gordon College in Wenham, wrote in a letter to Mrs. Aronson’s children that “she had talent to spare, a quiet brilliance that shone from behind the many obstacles that women painters encountered in her generation.’’

Mrs. Aronson’s art, he added, “was more than simply the work of an extraordinarily accomplished and talented artist — it is an indicator of who she was: a person of integrity, of high-minded purpose, of precision and care and long-range vision. She painted as though it mattered and as though her work should last forever. It is no accident that she has been commissioned to paint several of the most influential people in America, in the world.’’

Among those powerful portrait subjects were six associate justices of the US Supreme Court — Harry Blackmun, Ruth Bader Ginsburg, Anthony Kennedy, Sandra Day O’Connor, Antonin Scalia, and Clarence Thomas — which she finished between 1991 and 2009. Mrs. Aronson approached those commissions no differently than she did any of her paintings.

“She had a gift of conversation and connecting with people, and a great gift of friendship,’’ her son said. “She was able to connect with people very directly, almost immediately. She just had this disarming way with people, so dialogue was also a creative gift with her.’’

Because of their work, the justices couldn’t spare the time to sit for one of Mrs. Aronson’s portraits. Instead, she and her son, and his wife, Eileen, would travel to Washington so Mrs. Aronson could speak with each justice while Ben shot photographs from many angles. The prints were later laid out in her studio for reference as she painted so she could glean from the photos details such as the best expression in her subject’s eyes.

“Typically, we were given 20 minutes with the justices,’’ Ben said, and just as typically, the time stretched considerably longer — an hour or two — as Mrs. Aronson charmed each justice with her questions and conversations.

“She was spellbinding,’’ her son said. “She was somehow able to disarm them, and they opened up to her.’’

O’Connor took the Aronsons on a tour of the Supreme Court building, offering impromptu lectures and lessons about portraits of former justices, taking note of how a pose or a painting’s background elements illuminated the justice’s character and reflected a particular moment in history. “I am most impressed with your works. Congratulations on a superb creation,’’ O’Connor later wrote to Mrs. Aronson on Supreme Court stationery, after her portrait was finished.

When Mrs. Aronson told Blackmun that she had “the enormous task of somehow divining your essence,’’ he at first gruffly replied, “You couldn’t possibly know my greatest achievement.’’ Then he smiled and said, “I can wiggle my ears,’’ and proceeded to do so, adding that “it scores great points with the grandkids.’’

Georgianna B. Nyman was born in Boston, a daughter of Dr. Daniel Nyman, a physician, and the former Irene Mueller. The middle of three siblings, she grew up in foster care after her parents divorced when she was young.

Among her earliest mentors was her grandmother Annie Benson Muller, whose paintings of children and babies were well-known and used on Hood Milk Co. calendars. “She passed on her great love of learning and great love of painting,’’ Ben said. “I think that was my mother’s earliest inspiration to choose the visual arts as a lifetime devotion, an aspiration.’’

Mrs. Aronson attended the Longy School of Music and the School of the Museum of Fine Arts in Boston, and upon graduating from the latter was awarded the school’s coveted traveling fellowship, which she used to study art collections in Europe. A skilled pianist, she went on to perform as a singer while forging her painting career. “She used to joke that it was because she was a Gemini,’’ her son said of her dual pursuits.

One of her teachers at the Museum School was David Aronson, who was part of the Boston Expressionist movement. He asked her out the day after she graduated and they married a few years later, in 1956. For many years, he taught at Boston University, where he was the first chairman of what is now the School of Visual Arts. He died in 2015.

The couple’s Sudbury home “was like an informal small museum, with all sorts of sculptures and paintings,’’ said Ben, who lives in Framingham.

A service has been held for Mrs. Aronson, who in addition to her son leaves two daughters, Judy Webb of Los Angeles and Abigail Zocher of Sudbury; a sister, Dorothy Nyman of Brockton; three grandchildren; and a great-grandchild.

“The divine influence in the heart of man is a mystical connection that is the inspiration for my creative drive and intention,’’ Mrs. Aronson once wrote in an artist’s statement. “The presence of that best self, which lies in all of us, is the spirit I seek to discern and validate in my portraiture.’’

Mrs. Aronson, who died a few hours before turning 87, chose not to confine her religious contemplations to one creed. She likened spiritual beliefs to a large house with many windows on each floor, “some big, some small, some ornate, some simple, but the common denominator is that they all admit the same light, and it’s up to you to choose,’’ her son said.

“Then she would smile and say, ‘The real secret is to get to the roof where there’s nothing between you and the light at all.’ ’’

Bryan Marquard can be reached at bryan.marquard@globe.com.