Critics hated Impressionism at first because it broke the rules the Paris Salon had trained them to expect: smooth finish, dark varnish, a clear story. Loose, visible brushwork looked careless to eyes trained on academic painting, and reviewers said so in print.
The reaction was not mild. It was mockery, in some of the biggest papers in Paris.
An insult that became a name
On April 25, 1874, the critic Louis Leroy reviewed the group's first independent show for Le Charivari and called it the exhibition of the Impressionists, mocking Monet's Impression, Sunrise directly.
The name was meant to sting. The painters adopted it themselves a few years later.
It got worse before it got better
At the second group show, in April 1876, the critic Albert Wolff wrote in Le Figaro that five or six lunatics, one of them a woman, had rented a room to show their work.
He compared the effect of their paintings to a cat walking across piano keys.
Why the anger, really
Most Impressionists had already been turned down by the Salon jury, the only real venue for selling art in Paris at the time, which is exactly why they organized their own show instead.
Critics judged the paintings against a finish the painters were never trying to achieve. That mismatch, more than the paintings themselves, drove most of the ridicule.
I find Wolff's line almost funny now. He did not mean it as one.
What the numbers looked like
The first show drew about 3,500 visitors across a month. The official Salon that same year pulled in roughly half a million.
See how the group's reputation eventually turned around in Famous Impressionist Paintings.