But the reward is worthwhile, as no two pieces are ever identical, giving each piece a unique personality and life.

To help preserve the craft, Wang has roped his entire family into the trade. His youngest son, Wang Jianwei, 50, has mastered the techniques of indigo tank preparation; his second son, Wang Jianyong, 56, has taken charge of dyeing, paste preparation, and pattern application; and his eldest son, Wang Jianfeng, 57, handles the making of the templates. Even his granddaughter, who was born in the 2000s, has taken on pattern and product design.

Wang Jianyong, who has watched his father since he was a child, has decided to take up the family mantle.

He says that the transition from white cotton fabric to meticulously designed patterns in different hues of blue is like magic.

"It's like watching a child grow from babbling to maturity," he says, adding that the resulting sense of pride comes straight from the heart.

While upholding traditional techniques, the family members have also left their own stamp on the craft, and produced three shades of blue — dark, medium and light — and made use of a variety of techniques, including traditional Chinese painting, woodblock printing, and folk paper-cutting.

Wang Zhenxing and his family have also developed new products like backpacks, makeup bags, home decorations and hair accessories, and despite his years, he continues to work at the family dye house, promoting blue calico art.

Since their facility was named a national intangible cultural heritage protection base in 2006, visitors have come from across the country. It has received students from more than 100 institutes of higher learning, and international visitors from Japan, South Korea and Russia have also come to appreciate the art.

Wang Jianfeng still vividly remembers Li Ziqi's visit.

"She is clearly very into the inheritance and development of blue calico printing and dyeing," he says. "Thanks to her, more people have come to know the art, and we hope more will come."