The crucial moment is determined based on the glue's smell, color and texture.

Then comes the ingredients mixing, which varies with seasons.

"The portions have to change. For instance, the water content in the glue can be different due to seasonal changes, so the recipe has to be adjusted accordingly," Wei says.

He takes relief that many young people have joined the practice of the ink craft over the years.

It takes pain and responsibility to carry the craft forward since the glue preparation alone would expose one to a high-temperature working environment for hours, Wei explains.

Apart from taking care of ink production, Wei has gone to bookstores and stationery shops to get real-time market feedback.

"We need up-to-date information to carry out innovations while sticking to traditions," Wei says.

Yidege rolled out tailored ink products for school students about seven years ago.

"We cut back on the traditional Chinese medicine input to reduce the smell, while making the ink easier for them to write, such as saving them the trouble of putting in water," Wei says.

Last year, Yidege's ink sales increased by 20 percent over the previous year, which Wei attributed to the rise of traditional culture.

"Many primary schools have opened calligraphy classes," he notes.

In April this year, Yidege rolled out a gift box containing a delicate calligraphy brush, floral fragrance ink, celadon gourd-shaped inkstone, acrylic picture frame and colored Xuan paper, which has drawn the attention of many young consumers.