In 1982, Mr. Bates went to a closing party for a show of Mr. Rappaport’s work on Downing Street in the West Village. As Mr. Rappaport recalled, Mr. Bates was upset with him, because Mr. Rappaport had used a small gift from his father to take out an advertising spread in Artforum magazine to promote the show.

Image A photograph of a painting that Leo Bates completed in his storefront studio in 1984. Credit... Christopher Capozziello for The New York Times

“Fairly early in the evening, Leo got up after having a few drinks and he said: ‘Richard is a fool. He just demonstrated how closed the art world is and what a fool I am to even try,’ ” Mr. Rappaport remembered. “And he picked up a serving plate and hurled it at one of my paintings on the wall.” The two never spoke again.

Mr. Bates had a few paintings in group shows in the early ’80s, but from the time he moved to Brooklyn, virtually all that people saw in his hand were the signs he hung outside his buildings: apartment available, inquire inside.

“We didn’t talk to anyone about the art,” Mrs. Bates said.

Mrs. Bates worked in a private library at Bank of America, and they lived on her salary and their income from rentals, which Mr. Bates invested in stocks. But if Mr. Bates had stopped hanging out with painters, he had not stopped painting. In Brooklyn, he painted and drew obsessively. Asked why her husband had stopped selling his work, Mrs. Bates said: “He wanted to keep his body of work together. He wanted to show the progression.”

She did not say he hoped he would one day be discovered. But his meticulous documentation suggests as much. He dated each canvas and made slides of each painting. For a time, he set up a tripod and photographed each brush stroke in a painting. He made stop-motion animated films from them.

But in the moment, Mr. Bates did not want to share his work. He feared he would be copied. And until his small memorial two years ago, Mrs. Bates said, almost no one saw it. “Me, the carpenter who rented the garage, maybe a few friends,” she said.