The thread is dyed before any weaving starts. Yonezawa-ori is woven from yarn coloured with safflower and other plant dyes, and weaving houses remain in the city where the looms can be seen running. Because the dyeing happens first, the pattern is effectively settled while the threads are being arranged, before a single pick has been thrown — the design exists as an order of coloured yarns rather than as an image on cloth.

Compared with dyeing a finished fabric, this allows no correction after the fact, and the preparation consequently takes far longer than the weaving does. Safflower yields dye from the flower and has been grown in Yamagata for a long time, so the dyeing and the weaving developed as connected trades inside one district rather than as separate industries trading with each other. Yonezawa station has the Shinkansen, the city has universities and hospitals within it, and the winter snow is deep enough to shape the working year around indoor trades.

A district that dyes at the yarn stage carries its stock differently. Dyed thread has to exist before an order arrives, which means the work is not made to order so much as prepared in advance and then waited on — and the number of colours held becomes an asset in its own right, like a vocabulary. Nothing can be woven here that has not already been dyed, which puts the risk at the front of the process rather than the back. Look at the rolls of finished cloth on display and what you are really looking at is that inventory of colours, arranged into fabric after the fact.