Sitting with a Bai tie-dye master in Zhoucheng

We arrived in Zhoucheng on a Tuesday after the morning market had thinned, when the cobbled lane outside Duan Yinkai's courtyard still smelled faintly of pork fat and woodsmoke from breakfast. He was seated on a low wooden stool beside the vat, sleeves rolled to the elbow, folding a length of cotton along its grain. He did not look up when we entered. A neighbour's grandchild ran past with a plastic bucket, then a chicken, then nothing. The courtyard had the quiet of a room that has been doing the same work for a long time and has stopped announcing itself.

Duan is fifty-three. His mother taught him to fold and his grandmother taught her, and he is careful to say this without making it sound like a slogan. The Bai have been dyeing cloth with lan dian, the fermented indigo paste rendered from Strobilanthes cusia, since at least the Ming, though the family workshop in its current form dates only to 1987, when his father rebuilt the courtyard after the collective dyeing house in the village was disbanded. He tells us this matter-of-factly, the way another craftsman might mention the year he replaced a kiln.

The vat sits sunk into the floor near the north wall, a ceramic jar roughly the height of a kitchen stool, its rim worn smooth and slightly darker than the rest. The liquid inside is not the blue one expects. It is a deep yellow-green, the colour of pond water in late summer, with a metallic copper sheen riding the surface where the dye has begun to oxidise. A skin of indigo flowers, small dark bubbles, gathers along one edge. The smell is sharp and organic, closer to a stable than a paint shop: ammonia, plant rot, something faintly sweet underneath, like overripe fruit.

We sat with him for the better part of the morning. He had folded the cotton into a tight accordion, then bound it with hemp twine in a pattern of small even knots, working from memory. The pattern, he said, was called ban zhang hua, half-palm flower, one he has been folding since he was eleven. When he lowered the bundle into the vat, the cloth did not turn blue. It came out the same yellow-green as the liquid, heavy and dripping, and he laid it across a wooden frame to oxidise in the air. We watched the colour arrive. It took perhaps four minutes. The green darkened, then bruised, then settled into a blue we had no name for.

He dipped the same bundle eight times that morning. Between dips, the cloth rested. Between rests, he drank tea from a small ceramic cup, refilled twice from a thermos by his wife, Yang Cuifen, who passed through the courtyard on errands we did not understand and did not ask about. The rhythm was not theatrical. It was the rhythm of someone who has calculated, long ago, that the vat sets the pace and there is no argument to be had with it. The dye needs time with the air. The air takes the time it takes.

“The blue, we understood by then, was not a colour. It was a length of time made visible.”

Duan's hands are stained to the second knuckle, a blue so deep it reads almost black in shadow. He showed them to us without ceremony when we asked, turning them palm-up and then palm-down. The colour does not come off, he said. It has not come off in thirty years. He has tried lemon, vinegar, the harsh industrial soap they sell at the hardware store in Xizhou. None of it works. The indigo lives in the cracks of his skin and in the beds of his nails and along the lines of his palms, where it has settled into a topographic map of his working life.

Around eleven, a minibus pulled up at the end of the lane and a group of visitors came through the gate, ushered by a guide with a small flag. Duan stood, wiped his hands on a rag that did no good, and walked them through a five-minute version of what we had been watching for three hours. He folded a square of cotton, dipped it once, wrung it, unfolded it to applause, and sold it for forty yuan. The visitors took photographs and left. He sat back down. The vat continued at its own temperature. He returned to the bundle he had been working on before they arrived without comment, as though the interruption had been a small weather event.

Later, we asked about the difference. He thought for a while before answering. The demonstration, he said, is not dishonest, only compressed. A single dip produces a pale, uneven blue that fades in two washes. The cloth he was making for himself that morning would take twelve to sixteen dips across two days, with rests between, and the blue would hold for a generation. The visitors were not wrong to want to see something. There was simply not enough time in their visit for the thing itself to happen, and he did not begrudge them this. He shrugged and refilled his cup.

The vat must be fed. Every few days, Duan adds rice wine, lime, and fresh indigo paste in proportions he no longer measures. The fermentation is bacterial, a slow living chemistry, and a vat that is neglected for a week will collapse and have to be started again from scratch, which takes months. He keeps three vats in rotation, each at a slightly different stage. The oldest is eleven years old, by which he means the current ferment, the same continuous culture, has been alive in that jar since 2015. He speaks of it the way a baker speaks of a sourdough starter, with a mixture of affection and slight wariness.

His daughter, Duan Xiaolin, is twenty-six and lives in Kunming, where she works in graphic design. She comes back for the autumn festival and for two weeks in spring. She knows how to fold ban zhang hua and three other patterns, and she has told her father she does not yet know whether she will return to the courtyard for good. He does not press her. The workshop, he said, has survived the commune and the market and the tour buses, and it will survive his daughter making up her own mind. He said this without bitterness, the way a person describes the weather of a season they have already lived through.

By early afternoon the light in the courtyard had shifted and the bundle from the morning was hanging from a beam, drying in the breeze that came down from Cangshan. The blue was uneven in places where the twine had bound tightly, and where it had bound less tightly, the dye had crept in and softened the line. He looked at it for a moment, then turned back to the vat. The vat did not need him. He sat with it anyway. We sat with him. Outside the gate, the lane was quiet, and somewhere in the village a radio was playing something we could not place.

We left before the last dip. He walked us to the gate, hands in his pockets, and said come back in October, when the new indigo is harvested and the courtyard smells different. We said we would try. Walking back along the wall toward the bus, we passed three other workshops with their gates open, vats sunk in their floors, the same slow chemistry running in each. The blue, we understood by then, was not a colour. It was a length of time made visible, and it was still being made, one fold at a time, all along the lane behind us.