The commission of a lifetime for Amy Sherald has kickstarted a conversation about art, politics and culture

She is a Baltimore-based artist who only paints African-American subjects and always uses a muted palette. But last week, Amy Sherald became the art world’s latest sensation as her portrait of former first lady Michelle Obama was unveiled in Washington.

Sherald, 44, almost didn’t get to paint Obama. She put away her brushes for three years to care for her family in Georgia. Then, in 2012, she collapsed and underwent a heart transplant that meant she needed another year to recuperate.

The work – unveiled in Washington alongside a portrait of Barack Obama by well-known African-American artist Kehinde Wiley – is of a pale, grey-tinged first lady against a light-blue, featureless backdrop.

Play Video 2:19 Barack Obama thanks portrait artist for capturing Michelle's 'hotness' - video

It has prompted an unexpected art world discussion about realism and its relationship with more conceptual art.

Not everyone was enthusiastic about Sherald’s idiosyncratic take. The Philadelphia Inquirer said Sherald’s portrait made Obama look “more like Kerry Washington (an American actor) than Mrs O”. The New York Times’s Holland Cotter said he was anticipating “a bolder, more incisive image”.

The New Yorker’s Doreen St. Félix described the first lady’s portrait – in the artist’s trademark “grey scale”, a light charcoal with taupe undertones – as “shocking,” but went on to give it a ringing endorsement.

“Applied to Michelle Obama, the lack of brown in the skin feels first like a loss, and then like a real gain. This is a different Michelle, a woman evacuated of celebrity, who appears provisionally dreamlike, nearly a shadow.” Others wondered if the former first lady’s bare arms were a radical and defiant gesture.

What was artist’s message? Sherald has said she paints her subjects as archetypes. “I paint American people, and I tell American stories through the paintings I create,” she said at the unveiling ceremony.

“My approach to portraiture is conceptual. Once my paintings are complete, the models no longer exist as themselves. I see something bigger, more symbolic. I paint things I want to see. I paint as a way of looking for myself in the world.”

Obama had said she felt an instant “sista-girl” connection with Sherald. “She was so fly and poised. She was hip and cool in a way that was expected but also that was completely unexpected.”

Will Smith, editor of Art in America, said: “I’m amazed at how much energy is going into the discussion of painting and portraiture. I can’t remember a time when there was discussion about a picture in an old-fashioned medium in a positive way.”

Facebook Twitter Pinterest Baltimore artist Amy Sherald, who painted the official portrait of former first lady Michelle Obama. Photograph: Andrew Harnik/AP

He points to a renewed interest in realist painting, particularly among young black artists including California’s Henry Taylor, British artist Lynette Yiadom-Boakye, and Nigerian Toyin Ojih Odutola. “The portraits of the Obamas are part of that contemporary conversation in painting and art.”

The positive response to the portraits shows, Smith said, that “official state power being linked to some of the best expressions of black culture out there. That’s a powerful force at time when official governance in Washington is so despairing.”

Artist and critic Walter Robinson said: “‘Likeness’ is a traditional, boring and now fairly useless measure for the success of a portrait,” he says. “Instead, it should be read as a ‘sign’ that engages meaning and feeling.”

Obama’s choice of Sherald to represent her is likely to be a significant boost to the artist’s career, but Sherald said she was deeply aware of the scrutiny that would inevitably accompany the once-in-a-lifetime commission. “If I’d had her rest her chin on her fist, people would have said that I’d painted her giving the Black Power salute,” Sherald told the Baltimore Sun.

As America’s culture wars show no sign of relenting, artistic representation is itself a political battlefield. Last year, Dana Schutz, a well-known white female artist, came under intense criticism after her painting of civil rights-era lynching victim Emmett Till was exhibited at the Whitney Museum biennial.

The US painting world was rocked by accusations of sexual harassment levelled at painter Chuck Close, a wheelchair-user and the artist selected by former President Bill Clinton for his official portrait. A retrospective at the National Gallery in Washington was cancelled.

“The country is having a conversation about painting and that’s striking,” said Smith. “The presidential portraits are an affirmation that art can still have something really important to say.”