He kneels to eye level with children and speaks simply so they can understand.

Many primary schools now invite him to give lessons on cultural relics.

"I have two cupboards of gifts made by my little audiences, including a girl's note saying 'Marry me'", says Zhang with a blush.

Since 2008, many Chinese museums have opened for free. Museum, exhibition and visitor numbers have grown rapidly. By 2016, China had 4,873 museums and more than 30,000 exhibitions were held annually, drawing 900 million visitors.

Pictures of sensational exhibitions and rare treasures sweep social media, while books and documentaries are made into period dramas.

"Well-known interpreters are gaining followers. They are one of the most enchanting features of China's museums," Pan Shouyong, Professor of Anthropology and Museology at Minzu University of China, told Xinhua on Thursday, the annual International Museum Day.

Museums are adapting to the new environment. "In the past, Chinese museums considered collections and research their priorities, but now they focus on the public," says Pan.

In 2014, Zhang resigned his post at a state-owned enterprise and started a business educating teenagers about museums. He offers online and offline courses on exhibitions, sells books and organizes study trips abroad.

It was difficult at first, but Zhang has confidence, as the government called for social forces to participate in public culture services earlier this year.

He still volunteers in museums.

"I want to help young people develop an interest in museums, which are wonderful places to visit again and again," says Zhang.