“He didn’t like a haircut that looked like a haircut,” Didier Malige, a hairstylist and friend who worked with Mr. David on and off for several decades, said in a phone interview. “His philosophy was that you should be able to put your hands — or your boyfriend should be able to put his hands — in your hair and it would be the same.”

The salons were a hit, the stylists there often seeing 30 clients a day.

“He wanted us to be able to work fast, clean, no mistakes,” Jean-Christophe David, who worked in his father’s salons in various capacities and later on the business side, said in an interview.

In a free-spirited era of “sex, drugs and rock ’n’ roll,” said Tony Kent, a fashion photographer who worked with Mr. David on photo shoots, he was conservative and ambitious, which contributed to his success. That level of professionalism, Mr. Kent said, made Mr. David an asset at a time when not everyone was so focused.

“It was pretty volatile, what was going on, and he was one of the stable ones,” Mr. Kent said by phone. “He was the opposite of that. He was somebody you could totally count on.”